Gender roles. Roles of Men and Women in Society Essay

Sex jobs. Jobs of Men and Women in Society - Essay Example II. The organic make up of a person inside a general public has for quite some time been utilized to decide how that individual ought to act †¢ Biology isn't really a deciding variable in sexual orientation jobs †¢ In a large number of the social orders today, there is an inclination to attribute jobs as indicated by the organic cosmetics of the people inside them †¢ Men were given the places of intensity, not on the grounds that they could show improvement over ladies, but since of their natural cosmetics III. The society assumes a significant job in deciding the sex jobs of the people inside it †¢ The guardians of countless individuals in the public arena decide the sexual orientation jobs of their youngsters and inflexibly uphold them. †¢ Society is a ground-breaking power in the lives of the people inside it †¢ It is frequently incredibly hard for people to conflict with the jobs which have been set for them by their own social orders IV. Culture is another main consideration that decides the sexual orientation jobs of people in the social orders inside which they live. †¢ There are a wide range of societies around the globe and every ha its own assumptions regarding what jobs the individuals from each sex ought to embrace †¢ Other societies can't be decided by the western guidelines on account of the way that while there might be comparative societies, there are others which are totally extraordinary †¢ In a globalized culture, people are viewed as equivalent and will in general be given equivalent chances, with each sex playing out those undertakings which were customarily saved for the other V. The different jobs that are attributed to the different sexual orientations are for the most part controlled by the general public inside which people live just as by its way of life. Science just goes about as a marker to decide how the general public will mingle a person to carry on and it isn't in itself a definer of sex jobs Within the cutting edge world, sexual orientation jobs are beginning to become irrelevant Women can take up the jobs customarily held for men with a similar productivity and the opposite has likewise been demonstrated to be genuine The sex jobs are today gradually getting obscured and they may stop to exist by and large in future It is a reality that sex jobs have existed for nearly as long as mankind has existed and it is very conceivable that they will kee p on existing soon. They are a piece of the day by day lives of people and are showed inside the general public by recognizable factors, for example, how one carries on or show up. Sexual orientation jobs can be viewed as examples of sentiments esteemed proper or unseemly due to one’s sex and they get from the social desires for how individuals from the various sexes whether male or female, ought to carry on. A case of this is in the event that an individual believes themselves to be female, at that point she would be relied upon to show the attributes which are normally connected with being female, for example, being delicate, needy and expressive of their sentiments. There are different variables that are utilized to decide the sexual orientation jobs in the public arena and the most significant of these are natural, social, and social components. One would express that the natural make up of a person inside a general public has for some time been utilized to decide how tha t individual ought to act. In any case, there is yet to be evidence of the way that whether one is male or female, the person is brought into the world with the intrinsic information on the qualities that are regularly attributed to their sex (Zosuls et al 827). In

Ethics and Social Responsibility in International Business Research Paper

Morals and Social Responsibility in International Business - Research Paper Example This article focuses on that detached obligation alludes to a situation where the organization disregards from enjoying socially dangerous acts while dynamic duty is whereby organizations take part in activities that legitimately advance social targets. This paper announces that any fruitful endeavor begins with the client by understanding their tribulations and endeavoring to set up how these issues are identified with their requirements. With the expanding scene economy as of now, clients are getting the opportunity to be to a greater extent a blend of worldwide and neighborhood buyers. Today’s organizations are attempting to accomplish serious addition by offering types of assistance or items to achieve the prerequisites of the global customer. To make these organizations to viably create and showcase their products or potentially benefits all inclusive an away from of the social and moral obligations ought to be built up for all partners. These moral and social duty measures ought to be joined in a company’s DNA giving space for progressively ordinary and beneficial outcome on all partners. Morals generally focuses on lead or moral shades of malice that happen in an organization, establishment or any business endea vor. The lead is in this way investigated from the situation of an individual’s conduct or hierarchical conduct as a rule. It along these lines fundamental that whenever the firm’s resolve measures are cleaned, the customer’s mentality and that of the general public all in all is certain towards the firm. From this time forward, the pay amassed structure the deals are too much prone to stay consistently high. For instance I n the present world, enormous corporation’s drama ting universally support their companies’ picture with moral principles and social duty bonds. Previously and even in the advanced world, business included cruel exercises like human dealing, imperialism and subjection, this sort of business just met the advantages of one gathering against the other. Nonetheless, with the development of business morals, the universe of business has been changed to a point where the requests of the two gatherings are accomplished without meddling with human rights as proposed by Trevino and Nelson (147). Accordingly an organization is required to make as much benefits as possible as it adjusts to the moral rules of the general public both those set in the law and those exemplified under standard morals. Morals and social obligation defeats each viewpoint, little of huge in global business. Coming up next are a portion of the pragmatic business territories where this is a primary concern: Management methodology An extraordinary degree of supportable achievement is feasible in a representative/client encouraging condition. Where workers, customers and providers are dealt with benevolent, their

Coping with Panic Disorder While in College

Coping with Panic Disorder While in College Panic Disorder Coping Print Panic Disorder and College How to Cope With Panic Attacks While in College By Katharina Star, PhD facebook linkedin Katharina Star, PhD, is an expert on anxiety and panic disorder. Dr. Star is a professional counselor, and she is trained in creative art therapies and mindfulness. Learn about our editorial policy Katharina Star, PhD Medically reviewed by Medically reviewed by Steven Gans, MD on August 05, 2016 Steven Gans, MD is board-certified in psychiatry and is an active supervisor, teacher, and mentor at Massachusetts General Hospital. Learn about our Medical Review Board Steven Gans, MD Updated on July 23, 2019 PeopleImages/Getty Images   More in Panic Disorder Coping Symptoms Diagnosis Treatment Related Conditions Attending college is usually a fun and exciting time for most students. The college years often entail learning more about subjects you are interested in, expanding your social circle, and discovering who you are as you transition into adulthood. Of course, college students are also met with many stressors and challenges. Classes can be difficult, relationships can change, and keeping up with your new responsibilities can lead to a lot of stress. The college experience can be even more stressful if you are struggling with the symptoms of panic disorder. You may feel embarrassed about your anxiety symptoms and try to hide them from other students. Perhaps you are worried about having a full-blown panic attack while in class or at a social event. Despite this extra stress, people with panic disorder  can have a rewarding time while in college. The following offers some tips to manage panic disorder while attending college: Panic Disorder Symptoms Getting Help at College Most colleges and universities offer on-campus counseling services. Such help may be provided through certain higher education programs. For instance, the doctoral programs in clinical psychology and counseling often have supervised trainees who provide free or low-cost services. Additionally, many colleges and universities have health centers that may provide psychological services. Most colleges and universities provide a range of mental health services that are available to students and are both high quality and budget-friendly. Find Help From the 7 Best Online Anxiety Support Groups Even if counseling services are not available on campus, the university health center should be able to provide you with information on nearby clinics and therapists. Local mental health professionals can also be found by searching online or in a phonebook. It may take some time to get an appointment, so try to contact one as soon as symptoms occur. The sooner you get help, the quicker you can expect to start coping with your panic attacks. Getting Help for Social Anxiety Disorder at College Determine a Coping Plan Once you have found professional help and received a proper diagnosis, it is time to determine a coping plan. For example, you may start to deal with your symptoms by attending regularly scheduled therapy sessions, going to anxiety support groups, and following your prescription medication plan. When determining your coping plan, consider what is most problematic and decide on ways you can start working through these issues. For instance, you may worry the most about having a panic attack in class. Coping skills to get through your classes may include sitting close to the door so you can leave for a few minutes as you get through your panic attack. You may want to try breathing exercises, as these are easy to practice, can be done without anyone noticing, and can help lessen your anxiety. As you try different ways to cope with panic disorder, you will experience some setbacks and progress along the way. That should be expected and will only help you better understand yourself and how to manage your condition. It can be beneficial to track your progress using a journal or a panic attack diary. Keeping a record of your experiences can assist you in determining your triggers, most helpful coping strategies, and overall progress. How to Cope With Panic Attacks While in College Relationships and Panic Disorder From professors, fellow classmates, co-workers, friends, and romantic interests, relationships often play a big role in the life of a college student. Dealing with the symptoms of panic disorder can potentially interfere with your various relationships. However, it is possible to have healthy relationships while coping with panic disorder in college. Many people with panic disorder chose to keep their symptoms a secret, afraid of what others will harshly judge them for their condition. In many ways, it can be best not to tell others about your panic disorder until you have gotten to know them. Unfortunately, there are many myths about panic disorder that may cloud the views of others. Only explain your condition to those you have developed a close relationship with. Explaining Your Panic Disorder to Friends and Family Taking Care of Yourself With all the busyness and potential stress of college, be sure to carve out some time for your own personal needs. Your self-care routine can include activities that strengthen and nurture the physical, creative, spiritual, and social aspects of your life. Here are some examples: Physical: getting enough rest, participating in regular exercise, and practicing proper nutritionCreative: art class, journal writing, or playing an instrumentSpiritual: meditation, reading inspirational material, or attending church servicesSocial: joining campus clubs, participating in college events, and volunteering Regardless of what activities you chose, be sure to put time aside for your personal health and wellbeing. Taking care of yourself can help reduce your stress and anxiety. Additionally, practicing self-care can help you better cope with panic disorder while in college. How Students Can Make College Life Less Stressful

The Western Military Trajectory During The Gunpowder And...

The Western military trajectory finds many of the impetuses for a military revolution stemming from non-Western stimuli. Innovations such as the composite bow (introduced by the Hyksos), cavalry (accredited to Assyria and Persia), the stirrup (attributed to China), gunpowder (China), crossbow (China), and cannons (China) have been attributed to non-Western regions; however, it is the Western militaries that exploited these innovations to their full deadly potential and in the process created military revolutions. This paper will discuss how some of these exploitations affected the Western military trajectory during the Gunpowder and First Industrial Revolutions, most often leaving the non-Western militaries lagging behind. It will also†¦show more content†¦The French invasion of Italy was not only an early part of the Gunpowder Revolution and the beginning of the modern age of warfare, but it was one of the first attempts at building nation-states. At the time, Italy was divided into several city-states, sovereign regions formed by a city and its surrounding territories. Due to the small size of many city-states, their defense was turned over to mercenary captains, condottieri. The paid men who formed compagnie (companies) under the condottieri were most often foreigners who lacked loyalty to their paymasters. On the other hand, as France expanded and took over city-states such as Armagnac, Burgundy, Provence, Anjou, and Brittany, they would become a part the French nation and its military. As such, King Charles VIII became the leader of the most powerful state in Europe by advancing the nation-state instead of city-states. Nearly one and a half centuries later, Swedish King Gustavus II Adolphus would further advance the French artillery techniques and make modern modifications to the formation and maneuver of his troops during the Battle of Breitenfeld in 1631 against Count Johann Tilly, an Imperial commander. Tilly formed his forces in seve nteen tercios, large formation of pikemen and musketeers fifty men abreast and thirty men deep. This formation was deadly for everything in its forward path, but it didShow MoreRelatedThe Industrial Revolution And Latin America1609 Words   |  7 PagesThe Industrial Revolution Latin America in The Nineteenth Century ââ€"  Only Japan underwent a major industrial transformation during the Nineteenth Century. ââ€"  India, Egypt, Ottoman Empire, China and Latin America experimented in modern industry. ââ€"  They were nowhere near the kind of major social transformation that had taken place in Britain, Europe, North America and Japan. ââ€"  The profound impact of European and North American industrialization was hard to avoid. After Independence in Latin America

The Benefits of School Uniforms - 703 Words

The benefits of school uniforms are countless. Uniforms can help eliminate peer pressure among students and can also help students and parents save time and money. Violence can also be greatly reduced simply by wearing school uniforms. Although the wearing of uniforms has been widely practiced throughout European, African, and South American public schools, the practice has primarily been within private schools systems throughout the United States until recently (West). All public schools should be required to wear uniforms in order to promote a better all-around environment for students and administration alike. Students have a desire to â€Å"fit in†. They feel the need to be accepted by their peers. Fashion is one of the most important†¦show more content†¦Media coverage about nationwide school epidemics, in which assaults on teachers are frequent and students are routinely killed over designer clothing, have been constant over the past few years (Wilkins). School uniforms produce harmony within the walls of a school. When students and administration dress alike, it is very easy to spot outsiders. Because they are not dressed in uniform, it is immediately known that they do not belong there. It also diminishes gang related violence andShow MoreRelatedBenefits Of School Uniforms1640 Words   |  7 PagesAre school uniforms benefitting or discouraging children? School uniforms has brought up a rather large controversy of how they are either positive or negative. Uniforms made people talk about two sides to this dilemma. They can show community and equality as well as a bad s ide where children are brought to tears because they do not have a choice to show who they really are. What about the children’s emotions? There are various opinions that lead to the outcome of having school uniforms. Student’sRead MoreBenefits Of School Uniforms In School798 Words   |  4 PagesBeneficial Clothing for Schools Around the world, several schools require their students to wear school uniforms. Many students do not adore this idea, but do they truly know how it benefits them. Some wonder if these uniforms actually improve their learning and experiences in school. Numerous questions have arisen when schools consider this idea. The debate today is growing, as schools try to figure out how they can enhance their school. There are various improvements in school systems when they reachRead MoreEssay on The Benefits of School Uniforms in Public Schools2132 Words   |  9 Pagesstudents’ attend public schools and face some sort of violence that is associated with that school. It can be gang related or just simply bullying in the school. Because of these rising issues, parents are being forced to pull their children out of public school and home school them for their safety. Is this the best action for the children? Will they be missing out on many life skills that are learned while attend ing schools with peers their own age? How can the schools make our children feelRead MoreGraduation Speech : Benefits Of School Uniforms1144 Words   |  5 Pages8, 2016 Benefits of School Uniforms School uniforms are a hotly debated topic among parents of school-age children. Some schools and school districts require them, some don’t. There are also school districts in which students in certain grades are told to wear uniforms whereas other students are not. Regardless, parents are in an uproar over the issue, and there are several key reasons. First of all, many parents speak on the cost factor involved in requiring school uniforms. DependingRead MoreBenefits of School Uniforms for American High School Students855 Words   |  3 PagesAmerican high school students being compelled to wear uniforms while attending school is very contentious. The role of uniforms in the lives of a student is a very difficult topic to approach. The school authorities have been at an impasse when the decision whether students should wear uniforms is brought up. Uniforms for high school students are purposefully designed to identify a child as a student to a particular school. A single unique design of garments will play the part of the uniforms. The factRead MoreEssay on The Benefits of Uniform Adoption in Public Schools1278 Words   |  6 PagesNowadays, public school and many districts are discussing the possibilities of enforcing the uniform policy. In most places, many private schools already require students to have their mandatory uniforms; however, there are only a few public schools adopting this mandatory school-uniform polices as one of their enrollment requirements. The reason why not all public schools participated was because people believe that they are violating the freedom of choice when enforcing this mandatory uniform policy; yetRead MoreSchool Uniforms859 Words   |  4 Pages24 September 2017 School Uniforms Should Be Used In Schools School uniforms should be utilized within schools. There are plenty of benefits, including they cost less than buying regular school clothes would, as well as drastically decreasing peer pressure and bullying in the student body. Uniforms give students a sense of respect and responsibility. They create the ability for students to succeed in areas without the hassle of what they’re wearing. School uniforms improve school spirit, and createRead MoreShould School Uniforms be Mandatory? Essay1090 Words   |  5 Pagesopinion of whether schools should require students to wear uniforms. Some schools go through the same argument annually of whether to enforce school uniforms the following school year. A number of people argue that uniforms take away from the students’ individuality, while other people concur that uniforms generate unity within the school. Even though many people disagree with school uniforms, countless reasons are evident that uniforms should be mandatory. School uniforms provide schools with many positiveRead MoreShould Schools Uniforms be Manadatory? Essay1090 Words   |  5 PagesOne social benefit school uniforms are responsible for is providing Many debates form over the opinion of whether schools should require students to wear uniforms. Some schools go through the same argument annually of whether to enforce school uniforms the following school year. A number of people argue that uniforms take away from the students’ individuality, while other people concur that uniforms generate unity within the school. Even though many people disagree with school uniforms, countlessRead MoreShould School Uniforms Be Mandatory? A School Setting?1071 Words   |  5 PagesTopic: Enforcement of uniforms should be mandatory in a school setting Thesis: School uniforms in private and public schools are very beneficial to the educational institution to help promote better learning and positive social skills. I. Introduction: Allowing school uniforms into an educational environment, whether it be a college, university, or elementary, or high school setting would be a benefit to the entire institution. In short, uniforms have many positive benefits: preventing violence,

Barbed Wire By Mary Emeny Free Essays

Mary Emenys poem, Barbed Wire, depicts war as a negative force, destroying every decent aspect of human existence. Written during the Vietnam War, the work displays Emenys negative views on war. In one way or another everyone experiences and identifies with the presence of war. We will write a custom essay sample on Barbed Wire By Mary Emeny or any similar topic only for you Order Now Although some wars are fought for justifiable reasons, every war tears into the lives of those undeserving. The tragic effects of war consume the innocent creating an unconquerable path of entanglement. The physical effects of war overwhelm the nave causing pain and suffering. Initially, war entangles the lives of youth, destroying the innocence that they experience as an aspect of their life. The girl glid[ing] gracefully down the path (1) and the boy rid[ing] eagerly down the road (9) have their enjoyable realities striped by the harshness of war. Likewise, war enters womens lives creating turmoil. The woman who works deftly in the fields ( ) no longer is able to experience the offerings of life. The wire cuts, ( ) pushing her away from the normal flow of life. In addition, man undergoes tragic obstacles as a result of war. A man walks nobly and alone ( ) before the horrible effects of war set in on his life causing disruptions. War enters the life of man destroying the bond man shares with his beloved environment ( ). Although a great deal of physical effects exist in Emenys work, the spiritual consequences of war serve as the most devastating ones. The will and spirit of those amidst the harshness of war diminishes because of the seriousness of war. Prior to the complexities of war, the spirit flees gleefully to the clouds, ( ) illustrating the freedom one expresses without repression. As soon as the wire catches, ( ) or the war commences, and intervenes with the lives of innocent bystanders, the innocence is lost. Furthermore, the hearts of the untainted human beings experience demolition due to the irrationality of war. Before the tragedy of war enters the picture, a heart goes openly to the street, ( ) showing the freedom that one possesses until the wire snares, ( ) and the sense of innocence disappears. Significantly, as a direct result of the entanglement of war, mans mind suffers pain and misfortune. A mans mind grows in searching ( ) preceding the brutality of war, exhibiting the ability of man to explore his surroundings without interference. Wars hampering of the innocent limits man to certain life experiences that repress his potential. ). Barbed Wire illustrates how the severity of war detracts from the innocence within and surrounding humans. Men and women languish from the tangible results of war, encountering barriers when attempting to complete normal tasks. On the other hand, the spiritual consequences of war such as the repression of the mind, signify the tragedy involved when faced with war. Ultimately, war serves as an aspect of life that possesses the capacity to destroy human experiences and beliefs. How to cite Barbed Wire By Mary Emeny, Essay examples

USB Fan free essay sample

I. Introduction Electricity is a form of energy that is carried through wires. Without electricity, we cannot operate things in our home. We use it almost every minute from the time we get up in the morning until we go to bed at night. Electricity helps us in lots of ways. It helps us watch television, play computer games and bathe. Without electricity a lot of things we take for granted wouldnt be here today. Imagine living in the dark with no central heating or television or computer? How bad would that be? It would be the middle ages all over again. We all know that electricity is now in high-price and we must conserve it. And using this USB fan made up of recyclable CD’s, we can say that you will try to use it, you can conserve electricity and at the same time, you are enjoying the air from it. We will write a custom essay sample on USB Fan or any similar topic specifically for you Do Not WasteYour Time HIRE WRITER Only 13.90 / page Electric fan consume large usage of electricity and also our environment are being abused. So we need to conserve electricity and save Mother Nature. With this device that is made up of recyclable materials, you can use at the same time your computer and this USB fan, you will just install the USB in your PC then your PC will be the source of energy of this fan for it to move. So you can lessen the usage of electricity in using electric fan while playing PC. And also it can help our environment by using recyclable CD. The device is only made up of 2 recyclable CD, USB cable, plastic tube and small engine that can be an electric fan that can produce a pleasant air. It can help our environment by the use of the recyclable materials and it can also help us in conserving electricity because USB fan made of CD can only consume a little amount of electricity than the electric fan we usually use at home. And we can make sure that it can produce a pleasant air. You will just connect the USB connector in the CPU of the computer to make it move. Honestly, it is small if you will compare it to the electric fan we usually use in our home. We can use this fan while searching our assignment in our computer so that we don’t feel the hot temperature than can cause our sweating. This research is entitled USB fan made up of recyclable CD’S that help us to reduce the Consumption of Electricity, I chose this topic, because this USB fan can help us to reduce the consumption of electricity in our home, especially to the place like computer shop with a lot of computer that consumes high power of electricity. II. Statement of the Problem This study aims to answer the following: 1. How can USB fan help our environment? 2. How can USB fan made up of recycle CD’s lessen the consumption of electricity? 3. Who will benefit on using USB fan? 4. What are the effects of using USB fan? 5. Where can people use USB fan made up of recycle CD’s? III. Assumptions This study answers the question given in the statement: 1. The answers are valid and real. 2. USB fan can recycle technology waste products like CD. 3. It can only consume a little electricity than the electric fan we usually use. 4. All persons who have a computer in their house will benefit on this USB fan, especially a place like computer shop. 5. The effects are: People will lessen the consumption of electricity in their home. Instead of turning on your electric fan at home while making your research in your computer, you will just use your computer and conserve electricity. USB fan is cheaper than electric fans we usually use at home. 6. People can use it in their computer or laptop while doing some research or playing. IV. Scope and Delimitation This research focuses on how USB fan made up of recyclable CD’s helps people to conserve electricity in their house for their daily life. V. Significance of the Study This study aims to be beneficial to the following: STUDENTS who are using computer in their studies. SCHOOL where is a lot of computers are used by the students. COMPUTER SHOP OWNERS who own a lot of computers in their shop. PARENTS who spent so much on paying electricity bill in their home. VI. Definition of Terms CD – CD is a hard plastic disk approximately 12 cm/ 4 in. in a diameter on which information such as music or computer data is digitally encoded in format readable by laser beam. Fan – Fan is a device for moving air and also a device to circulate current of air. Small Engine – Small engine is something that supplies the drive force or energy to a movement, system, or trend. Universal Serial Bus (USB) USB is an industry standard developed in the mid-1990s that defines the cables, connectors, and communications protocols used in a bus for connection, communication and power supply between computers and electronic devices. Wire – Wire is strand of metal, usually copper, that is encased in plastic or another insulting material and is used to carry a electric current. \

Get Excellent Ideas for Topics of Illustration Essays

Get Excellent Ideas for Topics of Illustration Essays Writing an illustrative paper is not easy. Even more difficult is to find a suitable topic for it. But don’t worry because we’ll simplify all this for you. In this article, you learn what this kind of essay is and how to decide a topic for it. You can choose any of our suggested topics as well. They are perfect because they have been proposed by our experts who have years of experience. What Is an Illustration Essay? The Basics Before discussing the process of selection of good illustration essay topics for your papers, it is advisable to discuss the concept of this kind of paper quickly. As the name shows, it’s a paper that illustrates a topic. It can be a process, a strategy, a plan, or anything that can be described. Such essays have a lot of depth to them because the narrator has to covey intricate details to the readers. To write such a paper, you need to have: Excellent vocabulary and know-how of the technical terms involved. The ability to imagine the finest details of the process so that you can convey them. The skill to describe things and find good examples. How to Come Up with Interesting Illustration Essay Topics If the teacher has already decided the topic for you, clearly you just have to write a paper on it following the guidelines we provide about the actual writing process. But if you are leveraged to pick up a topic of your choice, don’t go for the most difficult college illustration essay topics. You might select them in an attempt to cover a unique area, and later, you might find it hard to access the relevant information. On the other hand, don’t pick the easiest topics as well. Your readers need to sense that reading the paper will add to their knowledge. So look for best illustration essay topics in the middle range between the common and rare ones. Interesting topics are related to engaging themes. They include acting, performing arts, fashion, diet, games, and vacations. You may even come up with interesting topics on the themes of education and relationships as well. Some Excellent Illustration Essay Topics for College Students In this guide, we offer you some topics that are teachers’ favorite. At the same time, they are relatively unique and have a huge potential for being informative if written the right way. Our topics relate to all sorts of areas. You will find topics related to games, education, and exercise, among other fields. We want to provide a lot of options for every writer. Therefore, our suggested topics belong to different areas of knowledge. They include: How coaches train football players? How to learn swimming for the Olympics? Difference between football and basketball. How to bring a balance between school and home activities? My first-day playing cricket. Importance of deploying psychological counselors at schools. Studying habits that make students high achievers. How to live on a budget in Dubai? Life, profession, and experiences of a teacher. How can a newcomer adjust in hostel life? How to make a cake? Easy tips to overcome your fears. Describe a fear you’ve had and how you took control over it. The role of music in exercise and workout. What is it like to be a vegan? How does it feel to be a nonnative in the country you have immigrated to? How to be proactive and avoid procrastination? Take a good look at all these great topics to write an illustration essay on. You might observe that you can demonstrate processes and/or examples in almost every single paper. That’s the beauty of this kind of paper. How to Write This Kind of Paper Finding good topics for an illustration essay is the first challenge you have to deal with. But the difficulties don’t stop there. You should know how to logically construct the paper so that all details are sufficiently covered. Let us elaborate on the process of writing with the help of an example. Suppose you have to be a writer and produce a paper on the topic – how expats live in Dubai. In the introductory section of the paper, you can identify the different categories of expats in Dubai. It’s important to identify those categories because the lifestyle of an expat depends upon a lot of factors, especially his/her origin. Suppose you identify four classes of expats in Dubai Europeans, Africans, Arab, and South Asians. You can divide the body of the paper into four paragraphs – one for each class of expats. In those paragraphs, you can touch upon several topics for illustration essay considering an average day in the life of an expat. They include people’s food, work routine, outdoor activities, shopping, and family time, etc. Finally, you will conclude your paper summing up all information. Do You Need an Expert to Suggest You a Topic? We’re sure if you needed a topic from the themes we have covered, you might have found one that you like. But if you think that the theme you wanted the topic from has not been covered, there’s still nothing to worry about. Let us know which theme or area you want the topics to be from, and our writers will devise interesting and easy illustration essay topics from that field. The process of placing an order at our site is fundamental. You just have to fill out a form, and the guru will start looking for the best topic options for you. We devise topics related to all kinds of fields, and our gurus are subject experts. You can totally count on our writers’ help. So when are you placing the order? Tell us your instructions now.

How to Write the Revised GRE Analytical Writing Essays

How to Write the Revised GRE Analytical Writing Essays When people study for the GRE exam, they often forget about the two Writing tasks, the Analyze an Issue Task and the Analyze an Argument Task,  facing them on test day. Thats a big mistake! No matter how great of a writer you are, its important to practice these essay prompts before taking the exam. The GRE Writing Section is a doozy, but heres a brief how-to for writing the essays. How to Write the GRE Issue Essay: Remember that the Issue task will present an issue statement or statements followed by specific task instructions that tell you how to respond to the issue. Heres an example from ETS:   To understand the most important characteristics of a society, one must study its major cities. Write a response in which you discuss the extent to which you agree or disagree with the statement and explain your reasoning for the position you take. In developing and supporting your position, you should consider ways in which the statement might or might not hold true and explain how these considerations shape your position. First, choose an angle. The good news about the GRE Analytical Writing scoring is that you get to write about the issue from any angle. For example, you could do any of the following or choose an approach of your own:Agree with the issueDisagree with the issueAgree with parts of the issue and disagree with othersShow how the issue has inherent logical flawsDemonstrate the validity of the issue with comparisons to modern societyConcede a few points of the issue but refute the most important part of the claim Second, choose a plan. Since you only have 30 minutes, you need to make the best use of your writing time as is possible. It would be foolish to jump into the writing without scratching out a brief outline of the details and examples you want to include to make your strongest argument Third, write it. Keeping your audience in mind (faculty members and trained GRE graders), write your essay quickly and concisely. You can go back afterward to make changes, but for now, get the essa y written. You cant be scored on an empty sheet of paper. More Sample Issue Essays Write the GRE Argument Essay: The Argument task will present you with an argument for or against something and give you specific details about how you must respond. Heres a sample Argument task: The following appeared as part of an article in a business magazine. A recent study rating 300 male and female Mentian advertising executives according to the average number of hours they sleep per night showed an association between the amount of sleep the executives need and the success of their firms. Of the advertising firms studied, those whose executives reported needing no more than 6 hours of sleep per night had higher profit margins and faster growth. These results suggest that if a business wants to prosper, it should hire only people who need less than 6 hours of sleep per night. Write a response in which you examine the stated and/or unstated assumptions of the argument. Be sure to explain how the argument depends on these assumptions and what the implications are for the argument if the assumptions prove unwarranted. First, analyze the details. What facts are considered evidence? What is the offered proof? What are the underlying assumptions? What claims are made? Which details are misleading? Second, analyze the logic. Follow the line of reasoning from sentence to sentence. Does the author make illogical assumptions? Is the movement from point A to B logically rational? Is the writer drawing valid conclusions from the facts? What is the author missing? Third, outline. Map out the biggest problems with the prompts logic and your alternative rationale and counterexamples. Come up with as much evidence and support you can think of to support your own claims. Think outside the box here! Fourth, write it. Again, keep your audience in mind (which rationale would work best to convince a faculty member) write your response quickly. Think less about semantics, grammar, and spelling, and more about demonstrating your analytical skills to the best of your ability. Sample GRE Argument Essays The Analytical Writing Tasks in a Nutshell So, basically, the two writing tasks on the GRE are complementary in that you get to formulate your own argument in the issue task and critique anothers argument in the argument task. Please be mindful of your time in each task, however, and practice ahead of time to ensure your best score possible.

Racism Essay Example | Topics and Well Written Essays - 250 words - 5

Racism - Essay Example This study is done because of such difference in physical location (Donaldson & Karen 37). Anthropology also studies various human races to help them determine how their lifestyle is connected to their past in relation to communication, culture and behaviors. Throughout scientific studies, there has been no proof of biological differences among individual because of race, it should be noted that all human are equal irrespective of their skin color, language, religion and culture. Scientific researchs shows that race is just a social aspect that has nothing to do with our biological and genetic origin. Race, according to various human activists, should not be the reason why certain individuals are looked upon as less human in our institutions and within the larger community. We should all start to look at one another in a different perspective because of the important things that we have learnt through them. Everyone should take it as a personal initiative to promote the spirit of togetherness to enable us make the world a better place for each

Case study in ethics Essay Example | Topics and Well Written Essays - 1500 words

Case study in ethics - Essay Example Thus, the popular appeal of a certain depiction that is rendered in an advertisement creates a condition of biased, shallow perception. This kind of perception is highly reductive. In this case study, I shall focus on the issue of the image of Obama in an advertisement that has a certain pedigree of racism and political labeling. This discourse shall be explained and engaged further in the succeeding parts of the paper. At the same time, aside from the construction of the image, the impression derived thereof shall be put into account by looking into the formal elements that make up the image. At the same time, there is also a need to clearly assess why the image creates an impression through certain sensibilities, which are political, cultural and sociological in nature and must be discussed in conjunction with the signs that parts of images create for the spectator to gaze. Looking at the elements of the image, Obama’s image is presented with sickle and hammer, which are embodiments of communism (â€Å"Image†). Another crucial thing to look at the image is the use of the terms â€Å"somewhere in Kenya a village is missing its idiot Obama† (â€Å"Empty Suit†). Together with the image comes the face of Obama, smiling and wearing formal attire that befits the campaigning needed for the elections. The advertisement has these elements that evoke a totally different level of problematic propositions and discourses of representation. To understand the points to be raised in this paper, there is a need to understand that the context of presidential elections must be duly considered since this defines how the image works and creates a certain standard for judgment. The first thing that must be understood is that the image is highly offensive, given that the signs and symbols that have been incorporated in the advertisement are tantamount to

Effects of Exercise on the Human Body

Effects of Exercise on the Human Body Exercise represents one the highest levels of extreme stresses to which the body can be exposed. Exercise physiology is the study of the function of the human body during various acute and chronic exercise conditions. These effects are significant during both short, high intensity exercise as well as with prolonged strenuous exercise such as done in endurance sports like marathons, ultramarathons, and road bicycle racing. In exercise, the liver generates extra glucose, while increased cardiovascular activity by the heart, and respiration by the lungs, provides an increased supply of oxygen. When exercise is very prolonged and strenuous, a decline, however, can occur in blood levels of glucose. In some individuals, this might even cause hypoglycemia and hypoxemia. There can also be cognitive and physical impairments due to dehydration. Another risk is low plasma sodium blood levels. Prolonged exercise is made possible by the human thermoregulation capacity to remove exercise waste hea t by sweat evaporation. This capacity evolved to enable early humans after many hours of persistence hunting to exhaust game animals that cannot remove so effectively exercise heat from their body. In general, the exercise-related measurements established for women follow the same general principles as those established for men, except for the quantitative differences caused by differences in body size, body composition, and levels of testosterone. In women, the values of muscle strength, pulmonary ventilation, and cardiac output (all variables related with muscle mass) are generally 60-75% of the exercise physiology values recorded in men. When measured in terms of strength per square centimeter, the female muscle can achieve the same force of contraction as that of a male. The functions of muscle tissues assume roles in homeostasis, as follows: Excitability Property of receiving and responding to stimuli such as the following: Neurotransmitters: Acetylcholine (ACh) stimulates skeletal muscle to contract, electrical stimuli: Applying electrical stimuli between cardiac and smooth muscle cells causes the muscles to contract, Applying a shock to skeletal muscle causes contraction, Hormonal stimuli: Oxytocin stimulates smooth muscle in the uterus to contract during labor.Contractility Ability to shorten. Extensibility Ability to stretch without damageElasticity Ability to return to original shape after extensionThrough contraction, muscle provides motion of the body (skeletal muscle), motion of blood (cardiac muscle), and motion of hollow organs such as the uterus, esophagus, stomach, intestines, and bladder (smooth muscle).Muscle tissue also helps maintain posture and produce heat. A large amount of body heat is produced by metabolism and by muscle con traction. Muscle contraction during shivering warms the body. Skeletal muscle consists of fibers (cells). These cells are up to 100 Â µm in diameter and often are as long as the muscle. Each contains sarcoplasm (cytoplasm) and multiple peripheral nuclei per fiber. Skeletal muscle is actually formed by the fusion of hundreds of embryonic cells. Other cell structures include the following:Each fiber is covered by a sarcolemma (plasma membrane). The sarcoplasmic reticulum (smooth endoplasmic reticulum) stores calcium, which is released into the sarcoplasm during muscle contraction. Transverse tubules (T tubules), which are extensions of the sarcolemma that penetrate cells, transmit electrical impulses from the sarcolemma inward, so electrical impulses penetrate deeply into the cell. Besides conducting electricity along their walls, T tubules contain extracellular fluid rich in glucose and oxygen.The sarcoplasm of fiber is rich in glycogen (glucose polymer) granules and myoglobin (oxygen-storing protein). It also is rich in mitochondria. Each fibe r contains hundreds to thousands of rodlike myofibrils, which are bundles of thin and thick protein chains termed myofilaments. From a cross-sectional view of a myofibril, each thick filament is surrounded by a hexagonal array of 6 thin filaments. Each thin filament is surrounded by a triangular array of thick filaments.myofilaments are composed of 3 proteins: actin, tropomyosin, and troponin. Thick myofilaments consist of bundles of approximately 200 myosin molecules. Myosin molecules look like double-headed golf clubs (both heads at the same end). The heads of the golf clubs are called myosin heads; they are also called cross-bridges because they link thick and thin filaments during contraction. They contain actin andadenosine triphosphate (ATP) binding sites. Myosin heads project out from the thick filaments, allowing them to bind to the thin filaments during contraction. Actin is a long chain of multiple globular proteins, similar in shape to kidney beans. Each globular subunit contains a myosin-binding site. Tropomyosin is a long strand of protein that covers the myosin-binding sites on actin when the muscle is relaxed. Troponin is a polypeptide complex that binds to tropomyosin, helping to position it over the myosin-binding sites on actin. During muscle contraction, calcium binds troponin, which causes tropomyosin to roll off of the myosin binding sites on actin. A muscle action potential travels over sarcolemma and enters the T tubules, causing the sarcoplasmic reticulum to release calcium into the sarcoplasm. This triggers the contractile process.Myosin cross-bridges pull on the actin myofilaments, causing the thin myofilaments of a sarcomere to slide toward the centers of the H zones.Deep fascia is a broad band of dense irregular connective tissue beneath and around muscle and organs. Deep fascia is different from superficial fascia, which is loose areolar connective tissue.Other connective-tissue components (all are extensions of deep fascia) include epimysium, which covers the entire muscle; perimysium, which penetrates into muscle and surrounds bundles of fibers called fascicles; and endomysium, which is delicate, barely visible, loose areolar tissue covering individual fibers (ie, individual cells).Tendons and aponeuroses are tough extensions of epimysium, perimysium, and endomysium. Tendons and aponeuroses are made of dense regular co nnective tissue and attach the muscle to bone or other muscle. Aponeuroses are broad, flat tendons. Tendon sheaths contain synovial fluid and enclose certain tendons. Tendon sheaths allow tendons to slide back and forth next to each other with lower friction. Tenosynovitis is inflammation of the tendon sheaths and tendons, especially those of the wrists, shoulders, and elbows. Tendons are not contractile and not very stretchy; furthermore, they are not very vascular and they heal poorly. Nerves convey impulses for muscular contraction. Nerves are bundles of nerve cell processes. Each nerve cell process (ie, axon) divides at its tip into a few to 10,000 branches called telodendria. At the end of each of these branches is an axon terminal that is rich in neurotransmitters.Blood provides nutrients and oxygen for contraction. An artery and a vein usually accompany a nerve that penetrates skeletal muscle. Arteries in muscles dilate during active muscular activity, thus increasing the supply of oxygen and glucose.A motor nerve is a bundle of axons that conducts nerve impulses away from the brain or spinal cord toward muscles. Each axon transmits an action potential (ie, nerve impulse), which is a burst of electricity. The nerve impulse travels along the axons at a steady rate, like fire travels along a fuse; however, nerve impulses travel extremely fast. Each axon has 4-2000 or more branches (ie, telodendria), with an average of 150 telodendria. Each separate branch suppli es a separate muscle cell. Thus, if an axon has 10 branches, it supplies 10 muscle fibers. Small motor units are for fine control of muscles; large motor units are for muscles that do not require such fine control.The neuromuscular junction is made of an axon terminal and the portion of the muscle fiber sarcolemma it nearly touches (called the motor endplate). The neurotransmitter released at the neuromuscular junction in skeletal muscle is ACh. The motor endplate is rich in thousands of ACh receptors; the receptors are integral proteins containing binding sites for ACh and sodium channels. Nerve impulse (action potential) reaches the axon terminal, which triggers calcium influx into the axon terminal.Calcium influx causes synaptic vesicles to release ACh via exocytosis. ACh diffuses across synaptic cleft.ACh binds to theACh receptor on the sarcolemma. Succinylcholine, a drug used to induce paralysis during surgery, binds to ACh receptors more tightly than ACh. Succinylcholine initially causes some depolarization, but then itbinds to the receptor, preventing ACh from binding. Therefore, it blocks the muscles stimulation by ACh, causing paralysis. Another drug that acts in a similar fashion is curare. These drugs do not cause pain relief or unconsciousness; thus, they are combined with other drugs during surgery. When ACh binds the receptor, it opens chemically regulated ion channels, which are sodium channels through the receptor molecule. Sodium, which is in high concentration outside cells and in low concentration inside cells, rushes into the cell through the channels.The cell, whose resting membrane potential along the inside of the membrane is negative when comparedwith the outside of the membrane, becomes positively charged along the inside of the membrane when sodium (a positive ion) rushes in. This change from a negative charge to a positive charge along the inner membrane is termed depolarization. The depolarization of one region of the sarcolemma (the motor endplate) initiates an action potential, which is a propagating wave of depolarization that travels (propagates) along the sarcolemma. Regions of membrane that become depolarized rapidly restore their proper ionic concentrations along their inner and outer surfaces in a process termed repolarization. (This process of depolarization, propagation, and repolarization is similar to dominoes that topple each other but also spring back into the upright position shortly afterward.)The action potential also propagates along the membrane lining the T tubules entering the cell. This action potential traveling along the T tubules causes the sarcoplasmic reticulum to release calcium into sarcoplasm.Calcium binds with troponin, causing it to pull on tropomyosin to change its or ientation, exposing myosin-binding sites on actin. An ATPase, which also functions as a myosin cross-bridging protein, splits ATP into adenosine diphosphate (ADP) + phosphate (P) in the previous contraction cycle. This energizes the myosin head. The energized myosin head, or cross-bridge, combines with myosin-binding sites on actin. Power stroke occurs. The attachment of the energized cross-bridge triggers a pivoting motion (ie, power stroke) of the myosin head. During the power stroke, ADP and P are released from the myosin cross-bridge. The power stroke causes thin actinmyofilaments to slide past thick myosin myofilaments toward the center of the A bands.ATP attaches to the myosin head again, allowing it to detach from actin. (In rigor mortis, an ATP deficiency occurs. Cross-bridges remain, and the muscles are rigid.)ATP is broken down to ADP and P, which cocks the myosin head again, preparing it to perform another power stroke if needed. Repeated detachment and reattachment of the cross-bridges results in shortening without much increase in tension during the shortening phase (isotonic contraction) or results in increased tension without shortening (isometric contraction).Release of the enzyme acetylcholinesterasein the neuromuscular junction destroys ACh and stops the generation of a muscle action potential. Calcium is taken back up (resequestered) in the sarcoplasmic reticulum, and myosin cross-bridges separate. ATP is required to separate myosin-actin cross-bridges. The muscle fiber resumes its resting state. The chemical energy that fuels muscular activities is ATP. For the first 5 or 6 seconds of muscle power, muscular activity can depend on the ATP that is already present in the muscle cells. Beyond this time, new amounts of ATP must be formed to enable the activation of muscular contractions that are needed to support longer and more vigorous physical activities. For activities that require a quick burst of energy that cannot be supplied by the ATP present in the muscle cells, the next 10-15 seconds of muscle power can be provided through the bodys use of the phosphagen system, which uses a substance called creatine phosphate to recycle ADP into ATP.4 For longer and more intense periods of physical activity, the body must rely on systems that break down the sugars (glucose) to produce ATP. The complete breakdown of glucose occurs in 2 ways: through anaerobic respiration (does not use oxygen) and through aerobic respiration (occurs in the presence of oxygen). The anaerobic use of gluco se to form ATP occurs as the body increases its muscle use beyond the capability of the phosphagen system to supply energy. In particular, the glycogen lactic acid system, through its anaerobic breakdown of glucose, provides approximately 30-40 seconds more of maximal muscle activity. For this system, each glucose molecule is split into 2 pyruvic acid molecules, and energy is released to form several ATP molecules, providing the extra energy. Then, the pyruvic acid partially breaks down further to produce lactic acid. If the lactic acid is allowed to accumulate in the muscle, one experiences muscle fatigue. At this point, the aerobic system must activate.The aerobic system in the body is used for sports that require an extensive and enduring expenditure of energy, such as a marathon race. Endurance sports absolutely require aerobic energy. A large amount of ATP must be provided to muscles to sustain the muscle power needed to perform such events without an excessive production of la ctic acid. This can only be accomplished when oxygen in the body is used to break down the pyruvic acid (that was produced anaerobically) into carbon dioxide, water, and energy by way of a very complex series of reactions known as the citric acid cycle. This cycle supports muscle usage for as long as the nutrients in the body last. The breakdown of pyruvic acid requires oxygen and slows or eliminates the accumulation of lactic acid. In summary, the 3 different muscle metabolic systems that supply the energy required for various activities are as follows: Phosphagen system (for 10- to 15-sec bursts of energy)Glycogen lactic acid system (for another 30-40 sec of energy)Aerobic system (provides a great deal of energy that is only limited by the bodys ability to supply oxygen and other important nutrients) Many sports require the use of a combination of these metabolic systems. By considering the vigor of a sports activity and its duration, one can estimate very closely which of the ene rgy systems are used for each activity. During muscular exercise, blood vessels in muscles dilate and blood flow is increased in order to increase the available oxygen supply. Up to a point, the available oxygen is sufficient to meet the energy needs of the body. However, when muscular exertion is very great, oxygen cannot be supplied to muscle fibers fast enough, and the aerobic breakdown of pyruvic acid cannot produce all the ATP required for further muscle contraction. During such periods, additional ATP is generated by anaerobic glycolysis. In the process, most of the pyruvic acid produced is converted to lactic acid. Although approximately 80% of the lactic acid diffuses from the skeletal muscles and is transported to the liver for conversion back to glucose or glycogen, some lactic acid accumulates in muscle tissue, making muscle contraction painful and causing fatigue. Ultimately, once adequate oxygen is available, lactic acid must be catabolized completely into carbon dioxide and water. After exercise has stopped, extra oxygen is required to metabolize lactic acid; to replenish ATP, phosphocreatine, and glycogen; and to replace (pay back) any oxygen that has been borrowed from hemoglobin, myoglobin (an iron-containing substance similar to hemoglobin that is found in muscle fibers), air in the lungs, and body fluids. The additional oxygen that must be taken into the body after vigorous exercise to restore all systems to their normal states is called oxygen debt. The debt is paid back by labored breathing that continues after exercise has stopped. Thus, the accumulation of lactic acid causes hard breathing and sufficient discomfort to stop muscle activity until homeostasis is restored.5 Eventually, muscle glycogen must also be restored. Restoration of muscle glycogen is accomplished through diet and may take several days, depending on the intensity of exercise. The maximum rate of oxygen consumption during the aerobic catabolism of pyruvic acid is called maximal oxygen uptake. Maximal oxygen uptake is determined by sex (higher in males), age (highest at approximately age 20 y), and size (increases with body size). Highly trained athletes can have maximal oxygen uptakes that are twice that of average people, probably owing to a combination of genetics and training. As a result, highly trained athletes are capable of greater muscular activity without increasing their lactic acid production and have lower oxygen debts, which is why they do not become short of breath as readily as untrained individuals. The best examples of light exercise are walking and light jogging. The muscles that are recruited during this type of exercise are those that contain a large amount of type I muscle cells, and, because these cells have a good blood supply, it is easy for fuels and oxygen to travel to the muscle. ATP consumption makes ADP available for new ATP synthesis. The presence of ADP (and the resulting synthesis of ATP) simulates the movement of hydrogen (H+) into the mitochondria; this, in turn, reduces the proton gradient and thus stimulates electron transport. The hydrogen on the reduced form of nicotinamide adenine dinucleotide (NADH) is used up, nicotinamide adenine dinucleotide (NAD) becomes available, and fatty acids and glucose are oxidized. Incidentally, the calcium released during contraction stimulates the enzymes in the Krebs cycle and stimulates the movement of the glucose transporter 4 (GLUT-4) from inside of the muscle cell to the cell membrane. Both these exercise-induced respon ses augment the elevation in fuel oxidation caused by the increase in ATP consumption. An increase in the pace of running simply results in an increased rate of fuel consumption, an increased fatty acid release, and, therefore, an increase in the rate of muscle fatty acid oxidation. However, if the intensity of the exercise increases even further, a stage is reached in which the rate of fatty acid oxidation becomes limited. The reasons why the rate of fatty acid oxidation reaches a maximum are not clear, but it is possible that the enzymes in the beta-oxidation pathway are saturated (ie, they reach a stage in which their maximal velocity [Vmax] is less than the rate of acetyl-coenzyme A [acetyl-CoA] consumption in the Krebs cycle). Alternatively, it may be that the availability of carnitine (the chemical required to transport the fatty acids into the mitochondria) becomes limited. Whatever the reason, the consequence is that as the pace rises, the demand for acetyl-CoA cannot be met by fatty acid oxidation alone. The accumulation of acetyl-CoA that was so effective at inhibiting the oxidation of glucose is no longer present, so pyruvate dehydrogenase starts working again and pyruvate is converted into acetyl-CoA. In other words, more of the glucose that enters the muscle cell is oxidized fully to carbon dioxide. Therefore, the energy used during moderate exercise is derived from a mixture of fatty acid and glucose oxidation. As the intensity of the exercise increases even further (ie, running at the pace of middle-distance races), the rate at which the muscles can extract glucose from the blood becomes limited. In other words, the rate of glucose transport reaches Vmax, either because the blood cannot supply the glucose fast enough or the number of GLUT-4s becomes limited. ATP generation cannot be serviced completely by exogenous fuels, and ATP levels decrease. Not only does this stimulate phosphofructokinase, it also stimulates glycogen phosphorylase. This me ans that glycogen stored within the muscle cells is broken down to provide glucose. Therefore, the fuel mix during strenuous exercise is composed of contributions from blood-borne glucose and fatty acids and from endogenously stored glycogen.Being fit (biochemically speaking) means that the individual has a well-developed cardiovascular system that can efficiently supply nutrients and oxygen to the muscles. Fit people have muscle cells that are well perfused with capillaries (ie, they have a good muscle blood supply). Their muscle cells also have a large number of mitochondria, and those mitochondria have a high activity of Krebs cycle enzymes, electron transport carriers, and oxidation enzymes. Individuals who are unfit must endure the consequences of a poorer blood supply, fewer mitochondria, less electron transport units, a lower activity of the Krebs cycle, and poorer activity of beta-oxidation enzymes. To generate ATP in the mitochondria, a steady supply of fuel and oxygen and decent activity of the oxidizing enzymes and carriers are needed. If any of these components are lacking, the rate at which ATP can be produced by mitochondria is compromised. Under these circumstances, the production of ATP by aerobic means is not sufficient to provide the muscles with sufficient ATP to sustain contractions. The result is anaerobic ATP generation using glycolysis. Increasing the flux through glycolysis but not increasing the oxidative consumption of the resulting pyruvate increases the production of lactate. The purpose of respiration is to provide oxygen to the tissues and to remove carbon dioxide from the tissues. To accomplish this, 4 major events must be regulated, as follows: Pulmonary ventilation. Diffusion of oxygen and carbon dioxide between the alveoli and the blood, Transport of oxygen and carbon dioxide in the blood and body fluids and to and from the cells, Regulation of ventilation and other aspects of respiration: Exercise causes these factors to change, but the body is designed to maintain homeostasisWhen one goes from a state of rest to a state of maximal intensity of exercise, oxygen consumption, carbon dioxide formation, and total pulmonary and alveolar ventilation increase by approximately 20-fold. A linear relationship exists between oxygen consumption and ventilation. At maximal exercise, pulmonary ventilation is 100-110 L/min, whereas maximal breathing capacity is 150-170 L/min. Thus, the maximal breathing capacity is approximately 50% greater than the actual pulmon ary ventilation during maximal exercise. This extra ventilation provides an element of safety that can be called on if the situation demands it (eg, at high altitudes, under hot conditions, abnormality in the respiratory system). Therefore, the respiratory system itself is not usually the most limiting factor in the delivery of oxygen to the muscles during maximal muscle aerobic metabolism. VO2 max is the rate of oxygen consumption under maximal aerobic metabolism. This rate in short-term studies is found to increase only 10% with the effect of training. However, that of a person who runs in marathons is 45% greater than that of an untrained person. This is believed to be partly genetically determined (eg, stronger respiratory muscles, larger chest size in relation to body size) and partly due to long-term training. Oxygen diffusing capacity is a measure of the rate at which oxygen can diffuse from the alveoli into the blood. An increase in diffusing capacity is observed in a state of maximal exercise. This results from the fact that blood flow through many of the pulmonary capillaries is sluggish in the resting state. In exercise, increased blood flow through the lungs causes all of the pulmonary capillaries to be perfused at their maximal level, providing a greater surface area through which oxygen can diffuse into the pulmonary capillary blood. Athletes who require greater amounts of oxygen per minute have been found to have higher diffusing capacities, but the exact reason why is not yet known. Although one would expect the oxygen pressure of arterial blood to decrease during strenuous exercise and carbon dioxide pressure of venous blood to increase far above normal, this is not the case. Both of these values remain close to normal. Stimulatory impulses from higher centers of the brain and from joint and muscle proprioceptive stimulatory reflexes account for the nervous stimulation of the respiratory and vasomotor center that provides almost exactly the pr oper increase in pulmonary ventilation to keep the blood respiratory gases almost normal. If nervous signals are too strong or weak, chemical factors bring about the final adjustment in respiration that is required to maintain homeostasis. Regular exercise makes the cardiovascular system more efficient at pumping blood and delivering oxygen to the exercise muscles. Releases of adrenaline and lactic acid into the blood result in an increase of the heart rate (HR). Basic definitions of terms are as follows:VO2 equals cardiac output times oxygen uptake necessary to supply oxygen to muscles. The Fick equation is the basis for determination of VO2. Exercises increase some of the different components of the cardiovascular system, such as stroke volume (SV), cardiac output, systolic blood pressure (BP), and mean arterial pressure. A greater percentage of the cardiac output goes to the exercising muscles. At rest, muscles receive approximately 20% of the total blood flow, but during exercise, the blood flow to muscles increases to 80-85%. To meet the metabolic demands of skeletal muscle during exercise, 2 major adjustments to blood flow must occur. First, cardiac output from the heart must increase. Second, blood flow from ina ctive organs and tissues must be redistributed to active skeletal muscle. Generally, the longer the duration of exercise, the greater the role the cardiovascular system plays in metabolism and performance during the exercise bout. An example would be the 100-meter sprint (little or no cardiovascular involvement) versus a marathon (maximal cardiovascular involvement). The cardiovascular system helps transport oxygen and nutrients to tissues, transport carbon dioxide and other metabolites to the lungs and kidneys, and distribute hormones throughout the body. The cardiovascular system also assists with thermoregulation.The pumping of blood by the heart requires the following 2 mechanisms to be efficient:Alternate periods of relaxation and contraction of the atria and ventriclesCoordinated opening and closing of the heart valves for unidirectional flow of blood The cardiac cycle is divided into 2 phases: ventricular diastole and ventricular systole.This phase begins with the opening of the atrioventricular (AV) valves. The mitral valve (located between the left atrium and left ventricle) opens when the left ventricular pressure falls below the left atrial pressure, and the blood from left atrium enters the left ventricle.Later, as the blood continues to flow into the left ventricle, the pressure in both chambers tends to equalize.At the end of the di astole, left atrial contractions cause an increase in left atrial pressure, thus again creating a pressure gradient between the left atrium and ventricle and forcing blood into the left ventricle.Ventricular systole begins with the contraction of the left ventricle, which is caused by the spread of an action potential over the left ventricle. The contraction of the left ventricle causes an increase in the left ventricular pressure. When this pressure is higher than the left atrial pressure, the mitral valve is closed abruptly.The left ventricular pressure continues to rise after the mitral valve is closed. When the left ventricular pressure rises above the pressure in the aorta, the aortic valve opens. This period between the closure of the mitral valve and the opening of the aortic valve is called isovolumetric contraction phase.The blood ejects out of the left ventricle and into the aorta once the aortic valve is opened. As the left ventricular contraction is continued, 2 processe s lead to a fall in the left ventricular pressure. These include a decrease in the strength of the ventricular contraction and a decrease in the volume of blood in the ventricle.When the left ventricular pressure falls below the aortic pressure, the aortic valve is closed. After the closure of the aortic valve, the left ventricular pressure falls rapidly as the left ventricle relaxes. When this pressure falls below the left atrial pressure, the mitral valve opens and allows blood to enter left ventricle. The period between the closure of the aortic valve closure and the opening of the mitral valve is called isovolumetric relaxation time. Right-sided heart chambers undergo the same phases simultaneously. Most of the work of the heart is completed when ventricular pressure exists. The greater the ventricular pressure, the greater the workload of the heart. Increases in BP dramatically increase the workload of the heart, and this is why hypertension is so harmful to the heart.Arterial BP is the pressure that is exerted against the walls of the vascular system. BP is determined by cardiac output and peripheral resistance. Arterial pressure can be estimated using a sphygmomanometer and a stethoscope. The reference range for males is 120/80 mm Hg; the reference range for females is 110/70 mm Hg. The difference between systolic and diastolic pressure is called the pulse pressure. The average pressure during a cardiac cycle is called the mean arterial pressure (MAP). MAP determines the rate of blood flow through the systemic circulation.During rest, MAP = diastolic BP + (0.33 X pulse pressure). For example, MAP = 80 + (0.33 X [120-80]), MAP = 93 mm Hg. During exercise, MAP = diastolic BP + (0.50 X pulse pressure). For example, MAP = 80 + (0.50 X [160-80]), MAP = 120 mm Hg. The heart has the ability to generate its own electrical activity, which is known as intrinsic rhythm. In the healthy heart, contraction is initiated in the sinoatrial (SA) node, which is often called the hearts pacemaker. If the SA node cannot set the rate, then other tissues in the heart are able to generate an electrical potential and establish the HR.The parasympathetic nervous system and the sympathetic nervous system affect a personsHR. Parasympathetic nervous system: The vagus nerve originates in the medulla and innervates the SA and AV nodes. The nerve releases ACh as the neurotransmitter. The response is a decrease in SA node and AV node activity, which causes a decrease in HR. Sympathetic nervous system: The nerves arise from the spinal cord and innervate the SA node and ventricular muscle mass. The nerves release norepinephrine as the neurotransmitter. The response is an increase in HR and a force of contraction of the ventricles.At rest, sympathetic and parasympathetic ne rvous stimulation are in balance. During exercise, parasympathetic stimulation decreases and sympathetic stimulation increases. Several factors can alter sympathetic nervous system input.Baroreceptors are groups of neurons located in the carotid arteries, the arch of aorta, and the right atrium. These neurons sense changes in pressure in the vascular system. An increase in BP results in an increase in parasympathetic activity except during exercise, when the sympathetic activity overrides the parasympathetic activity. Chemoreceptors are groups of neurons located in the arch of the aorta and the carotid arteries. These neurons sense changes in oxygen concentration. When oxygen concentration in the blood is decreased, parasympathetic activity decreasesand sympathetic activity increases. Temperature receptors are neurons located throughout the body. These neurons are sensitive to changes in body temperature. As temperature increases, sympathetic activity increases to cool Effects of Exercise on the Human Body Effects of Exercise on the Human Body Exercise represents one the highest levels of extreme stresses to which the body can be exposed. Exercise physiology is the study of the function of the human body during various acute and chronic exercise conditions. These effects are significant during both short, high intensity exercise as well as with prolonged strenuous exercise such as done in endurance sports like marathons, ultramarathons, and road bicycle racing. In exercise, the liver generates extra glucose, while increased cardiovascular activity by the heart, and respiration by the lungs, provides an increased supply of oxygen. When exercise is very prolonged and strenuous, a decline, however, can occur in blood levels of glucose. In some individuals, this might even cause hypoglycemia and hypoxemia. There can also be cognitive and physical impairments due to dehydration. Another risk is low plasma sodium blood levels. Prolonged exercise is made possible by the human thermoregulation capacity to remove exercise waste hea t by sweat evaporation. This capacity evolved to enable early humans after many hours of persistence hunting to exhaust game animals that cannot remove so effectively exercise heat from their body. In general, the exercise-related measurements established for women follow the same general principles as those established for men, except for the quantitative differences caused by differences in body size, body composition, and levels of testosterone. In women, the values of muscle strength, pulmonary ventilation, and cardiac output (all variables related with muscle mass) are generally 60-75% of the exercise physiology values recorded in men. When measured in terms of strength per square centimeter, the female muscle can achieve the same force of contraction as that of a male. The functions of muscle tissues assume roles in homeostasis, as follows: Excitability Property of receiving and responding to stimuli such as the following: Neurotransmitters: Acetylcholine (ACh) stimulates skeletal muscle to contract, electrical stimuli: Applying electrical stimuli between cardiac and smooth muscle cells causes the muscles to contract, Applying a shock to skeletal muscle causes contraction, Hormonal stimuli: Oxytocin stimulates smooth muscle in the uterus to contract during labor.Contractility Ability to shorten. Extensibility Ability to stretch without damageElasticity Ability to return to original shape after extensionThrough contraction, muscle provides motion of the body (skeletal muscle), motion of blood (cardiac muscle), and motion of hollow organs such as the uterus, esophagus, stomach, intestines, and bladder (smooth muscle).Muscle tissue also helps maintain posture and produce heat. A large amount of body heat is produced by metabolism and by muscle con traction. Muscle contraction during shivering warms the body. Skeletal muscle consists of fibers (cells). These cells are up to 100 Â µm in diameter and often are as long as the muscle. Each contains sarcoplasm (cytoplasm) and multiple peripheral nuclei per fiber. Skeletal muscle is actually formed by the fusion of hundreds of embryonic cells. Other cell structures include the following:Each fiber is covered by a sarcolemma (plasma membrane). The sarcoplasmic reticulum (smooth endoplasmic reticulum) stores calcium, which is released into the sarcoplasm during muscle contraction. Transverse tubules (T tubules), which are extensions of the sarcolemma that penetrate cells, transmit electrical impulses from the sarcolemma inward, so electrical impulses penetrate deeply into the cell. Besides conducting electricity along their walls, T tubules contain extracellular fluid rich in glucose and oxygen.The sarcoplasm of fiber is rich in glycogen (glucose polymer) granules and myoglobin (oxygen-storing protein). It also is rich in mitochondria. Each fibe r contains hundreds to thousands of rodlike myofibrils, which are bundles of thin and thick protein chains termed myofilaments. From a cross-sectional view of a myofibril, each thick filament is surrounded by a hexagonal array of 6 thin filaments. Each thin filament is surrounded by a triangular array of thick filaments.myofilaments are composed of 3 proteins: actin, tropomyosin, and troponin. Thick myofilaments consist of bundles of approximately 200 myosin molecules. Myosin molecules look like double-headed golf clubs (both heads at the same end). The heads of the golf clubs are called myosin heads; they are also called cross-bridges because they link thick and thin filaments during contraction. They contain actin andadenosine triphosphate (ATP) binding sites. Myosin heads project out from the thick filaments, allowing them to bind to the thin filaments during contraction. Actin is a long chain of multiple globular proteins, similar in shape to kidney beans. Each globular subunit contains a myosin-binding site. Tropomyosin is a long strand of protein that covers the myosin-binding sites on actin when the muscle is relaxed. Troponin is a polypeptide complex that binds to tropomyosin, helping to position it over the myosin-binding sites on actin. During muscle contraction, calcium binds troponin, which causes tropomyosin to roll off of the myosin binding sites on actin. A muscle action potential travels over sarcolemma and enters the T tubules, causing the sarcoplasmic reticulum to release calcium into the sarcoplasm. This triggers the contractile process.Myosin cross-bridges pull on the actin myofilaments, causing the thin myofilaments of a sarcomere to slide toward the centers of the H zones.Deep fascia is a broad band of dense irregular connective tissue beneath and around muscle and organs. Deep fascia is different from superficial fascia, which is loose areolar connective tissue.Other connective-tissue components (all are extensions of deep fascia) include epimysium, which covers the entire muscle; perimysium, which penetrates into muscle and surrounds bundles of fibers called fascicles; and endomysium, which is delicate, barely visible, loose areolar tissue covering individual fibers (ie, individual cells).Tendons and aponeuroses are tough extensions of epimysium, perimysium, and endomysium. Tendons and aponeuroses are made of dense regular co nnective tissue and attach the muscle to bone or other muscle. Aponeuroses are broad, flat tendons. Tendon sheaths contain synovial fluid and enclose certain tendons. Tendon sheaths allow tendons to slide back and forth next to each other with lower friction. Tenosynovitis is inflammation of the tendon sheaths and tendons, especially those of the wrists, shoulders, and elbows. Tendons are not contractile and not very stretchy; furthermore, they are not very vascular and they heal poorly. Nerves convey impulses for muscular contraction. Nerves are bundles of nerve cell processes. Each nerve cell process (ie, axon) divides at its tip into a few to 10,000 branches called telodendria. At the end of each of these branches is an axon terminal that is rich in neurotransmitters.Blood provides nutrients and oxygen for contraction. An artery and a vein usually accompany a nerve that penetrates skeletal muscle. Arteries in muscles dilate during active muscular activity, thus increasing the supply of oxygen and glucose.A motor nerve is a bundle of axons that conducts nerve impulses away from the brain or spinal cord toward muscles. Each axon transmits an action potential (ie, nerve impulse), which is a burst of electricity. The nerve impulse travels along the axons at a steady rate, like fire travels along a fuse; however, nerve impulses travel extremely fast. Each axon has 4-2000 or more branches (ie, telodendria), with an average of 150 telodendria. Each separate branch suppli es a separate muscle cell. Thus, if an axon has 10 branches, it supplies 10 muscle fibers. Small motor units are for fine control of muscles; large motor units are for muscles that do not require such fine control.The neuromuscular junction is made of an axon terminal and the portion of the muscle fiber sarcolemma it nearly touches (called the motor endplate). The neurotransmitter released at the neuromuscular junction in skeletal muscle is ACh. The motor endplate is rich in thousands of ACh receptors; the receptors are integral proteins containing binding sites for ACh and sodium channels. Nerve impulse (action potential) reaches the axon terminal, which triggers calcium influx into the axon terminal.Calcium influx causes synaptic vesicles to release ACh via exocytosis. ACh diffuses across synaptic cleft.ACh binds to theACh receptor on the sarcolemma. Succinylcholine, a drug used to induce paralysis during surgery, binds to ACh receptors more tightly than ACh. Succinylcholine initially causes some depolarization, but then itbinds to the receptor, preventing ACh from binding. Therefore, it blocks the muscles stimulation by ACh, causing paralysis. Another drug that acts in a similar fashion is curare. These drugs do not cause pain relief or unconsciousness; thus, they are combined with other drugs during surgery. When ACh binds the receptor, it opens chemically regulated ion channels, which are sodium channels through the receptor molecule. Sodium, which is in high concentration outside cells and in low concentration inside cells, rushes into the cell through the channels.The cell, whose resting membrane potential along the inside of the membrane is negative when comparedwith the outside of the membrane, becomes positively charged along the inside of the membrane when sodium (a positive ion) rushes in. This change from a negative charge to a positive charge along the inner membrane is termed depolarization. The depolarization of one region of the sarcolemma (the motor endplate) initiates an action potential, which is a propagating wave of depolarization that travels (propagates) along the sarcolemma. Regions of membrane that become depolarized rapidly restore their proper ionic concentrations along their inner and outer surfaces in a process termed repolarization. (This process of depolarization, propagation, and repolarization is similar to dominoes that topple each other but also spring back into the upright position shortly afterward.)The action potential also propagates along the membrane lining the T tubules entering the cell. This action potential traveling along the T tubules causes the sarcoplasmic reticulum to release calcium into sarcoplasm.Calcium binds with troponin, causing it to pull on tropomyosin to change its or ientation, exposing myosin-binding sites on actin. An ATPase, which also functions as a myosin cross-bridging protein, splits ATP into adenosine diphosphate (ADP) + phosphate (P) in the previous contraction cycle. This energizes the myosin head. The energized myosin head, or cross-bridge, combines with myosin-binding sites on actin. Power stroke occurs. The attachment of the energized cross-bridge triggers a pivoting motion (ie, power stroke) of the myosin head. During the power stroke, ADP and P are released from the myosin cross-bridge. The power stroke causes thin actinmyofilaments to slide past thick myosin myofilaments toward the center of the A bands.ATP attaches to the myosin head again, allowing it to detach from actin. (In rigor mortis, an ATP deficiency occurs. Cross-bridges remain, and the muscles are rigid.)ATP is broken down to ADP and P, which cocks the myosin head again, preparing it to perform another power stroke if needed. Repeated detachment and reattachment of the cross-bridges results in shortening without much increase in tension during the shortening phase (isotonic contraction) or results in increased tension without shortening (isometric contraction).Release of the enzyme acetylcholinesterasein the neuromuscular junction destroys ACh and stops the generation of a muscle action potential. Calcium is taken back up (resequestered) in the sarcoplasmic reticulum, and myosin cross-bridges separate. ATP is required to separate myosin-actin cross-bridges. The muscle fiber resumes its resting state. The chemical energy that fuels muscular activities is ATP. For the first 5 or 6 seconds of muscle power, muscular activity can depend on the ATP that is already present in the muscle cells. Beyond this time, new amounts of ATP must be formed to enable the activation of muscular contractions that are needed to support longer and more vigorous physical activities. For activities that require a quick burst of energy that cannot be supplied by the ATP present in the muscle cells, the next 10-15 seconds of muscle power can be provided through the bodys use of the phosphagen system, which uses a substance called creatine phosphate to recycle ADP into ATP.4 For longer and more intense periods of physical activity, the body must rely on systems that break down the sugars (glucose) to produce ATP. The complete breakdown of glucose occurs in 2 ways: through anaerobic respiration (does not use oxygen) and through aerobic respiration (occurs in the presence of oxygen). The anaerobic use of gluco se to form ATP occurs as the body increases its muscle use beyond the capability of the phosphagen system to supply energy. In particular, the glycogen lactic acid system, through its anaerobic breakdown of glucose, provides approximately 30-40 seconds more of maximal muscle activity. For this system, each glucose molecule is split into 2 pyruvic acid molecules, and energy is released to form several ATP molecules, providing the extra energy. Then, the pyruvic acid partially breaks down further to produce lactic acid. If the lactic acid is allowed to accumulate in the muscle, one experiences muscle fatigue. At this point, the aerobic system must activate.The aerobic system in the body is used for sports that require an extensive and enduring expenditure of energy, such as a marathon race. Endurance sports absolutely require aerobic energy. A large amount of ATP must be provided to muscles to sustain the muscle power needed to perform such events without an excessive production of la ctic acid. This can only be accomplished when oxygen in the body is used to break down the pyruvic acid (that was produced anaerobically) into carbon dioxide, water, and energy by way of a very complex series of reactions known as the citric acid cycle. This cycle supports muscle usage for as long as the nutrients in the body last. The breakdown of pyruvic acid requires oxygen and slows or eliminates the accumulation of lactic acid. In summary, the 3 different muscle metabolic systems that supply the energy required for various activities are as follows: Phosphagen system (for 10- to 15-sec bursts of energy)Glycogen lactic acid system (for another 30-40 sec of energy)Aerobic system (provides a great deal of energy that is only limited by the bodys ability to supply oxygen and other important nutrients) Many sports require the use of a combination of these metabolic systems. By considering the vigor of a sports activity and its duration, one can estimate very closely which of the ene rgy systems are used for each activity. During muscular exercise, blood vessels in muscles dilate and blood flow is increased in order to increase the available oxygen supply. Up to a point, the available oxygen is sufficient to meet the energy needs of the body. However, when muscular exertion is very great, oxygen cannot be supplied to muscle fibers fast enough, and the aerobic breakdown of pyruvic acid cannot produce all the ATP required for further muscle contraction. During such periods, additional ATP is generated by anaerobic glycolysis. In the process, most of the pyruvic acid produced is converted to lactic acid. Although approximately 80% of the lactic acid diffuses from the skeletal muscles and is transported to the liver for conversion back to glucose or glycogen, some lactic acid accumulates in muscle tissue, making muscle contraction painful and causing fatigue. Ultimately, once adequate oxygen is available, lactic acid must be catabolized completely into carbon dioxide and water. After exercise has stopped, extra oxygen is required to metabolize lactic acid; to replenish ATP, phosphocreatine, and glycogen; and to replace (pay back) any oxygen that has been borrowed from hemoglobin, myoglobin (an iron-containing substance similar to hemoglobin that is found in muscle fibers), air in the lungs, and body fluids. The additional oxygen that must be taken into the body after vigorous exercise to restore all systems to their normal states is called oxygen debt. The debt is paid back by labored breathing that continues after exercise has stopped. Thus, the accumulation of lactic acid causes hard breathing and sufficient discomfort to stop muscle activity until homeostasis is restored.5 Eventually, muscle glycogen must also be restored. Restoration of muscle glycogen is accomplished through diet and may take several days, depending on the intensity of exercise. The maximum rate of oxygen consumption during the aerobic catabolism of pyruvic acid is called maximal oxygen uptake. Maximal oxygen uptake is determined by sex (higher in males), age (highest at approximately age 20 y), and size (increases with body size). Highly trained athletes can have maximal oxygen uptakes that are twice that of average people, probably owing to a combination of genetics and training. As a result, highly trained athletes are capable of greater muscular activity without increasing their lactic acid production and have lower oxygen debts, which is why they do not become short of breath as readily as untrained individuals. The best examples of light exercise are walking and light jogging. The muscles that are recruited during this type of exercise are those that contain a large amount of type I muscle cells, and, because these cells have a good blood supply, it is easy for fuels and oxygen to travel to the muscle. ATP consumption makes ADP available for new ATP synthesis. The presence of ADP (and the resulting synthesis of ATP) simulates the movement of hydrogen (H+) into the mitochondria; this, in turn, reduces the proton gradient and thus stimulates electron transport. The hydrogen on the reduced form of nicotinamide adenine dinucleotide (NADH) is used up, nicotinamide adenine dinucleotide (NAD) becomes available, and fatty acids and glucose are oxidized. Incidentally, the calcium released during contraction stimulates the enzymes in the Krebs cycle and stimulates the movement of the glucose transporter 4 (GLUT-4) from inside of the muscle cell to the cell membrane. Both these exercise-induced respon ses augment the elevation in fuel oxidation caused by the increase in ATP consumption. An increase in the pace of running simply results in an increased rate of fuel consumption, an increased fatty acid release, and, therefore, an increase in the rate of muscle fatty acid oxidation. However, if the intensity of the exercise increases even further, a stage is reached in which the rate of fatty acid oxidation becomes limited. The reasons why the rate of fatty acid oxidation reaches a maximum are not clear, but it is possible that the enzymes in the beta-oxidation pathway are saturated (ie, they reach a stage in which their maximal velocity [Vmax] is less than the rate of acetyl-coenzyme A [acetyl-CoA] consumption in the Krebs cycle). Alternatively, it may be that the availability of carnitine (the chemical required to transport the fatty acids into the mitochondria) becomes limited. Whatever the reason, the consequence is that as the pace rises, the demand for acetyl-CoA cannot be met by fatty acid oxidation alone. The accumulation of acetyl-CoA that was so effective at inhibiting the oxidation of glucose is no longer present, so pyruvate dehydrogenase starts working again and pyruvate is converted into acetyl-CoA. In other words, more of the glucose that enters the muscle cell is oxidized fully to carbon dioxide. Therefore, the energy used during moderate exercise is derived from a mixture of fatty acid and glucose oxidation. As the intensity of the exercise increases even further (ie, running at the pace of middle-distance races), the rate at which the muscles can extract glucose from the blood becomes limited. In other words, the rate of glucose transport reaches Vmax, either because the blood cannot supply the glucose fast enough or the number of GLUT-4s becomes limited. ATP generation cannot be serviced completely by exogenous fuels, and ATP levels decrease. Not only does this stimulate phosphofructokinase, it also stimulates glycogen phosphorylase. This me ans that glycogen stored within the muscle cells is broken down to provide glucose. Therefore, the fuel mix during strenuous exercise is composed of contributions from blood-borne glucose and fatty acids and from endogenously stored glycogen.Being fit (biochemically speaking) means that the individual has a well-developed cardiovascular system that can efficiently supply nutrients and oxygen to the muscles. Fit people have muscle cells that are well perfused with capillaries (ie, they have a good muscle blood supply). Their muscle cells also have a large number of mitochondria, and those mitochondria have a high activity of Krebs cycle enzymes, electron transport carriers, and oxidation enzymes. Individuals who are unfit must endure the consequences of a poorer blood supply, fewer mitochondria, less electron transport units, a lower activity of the Krebs cycle, and poorer activity of beta-oxidation enzymes. To generate ATP in the mitochondria, a steady supply of fuel and oxygen and decent activity of the oxidizing enzymes and carriers are needed. If any of these components are lacking, the rate at which ATP can be produced by mitochondria is compromised. Under these circumstances, the production of ATP by aerobic means is not sufficient to provide the muscles with sufficient ATP to sustain contractions. The result is anaerobic ATP generation using glycolysis. Increasing the flux through glycolysis but not increasing the oxidative consumption of the resulting pyruvate increases the production of lactate. The purpose of respiration is to provide oxygen to the tissues and to remove carbon dioxide from the tissues. To accomplish this, 4 major events must be regulated, as follows: Pulmonary ventilation. Diffusion of oxygen and carbon dioxide between the alveoli and the blood, Transport of oxygen and carbon dioxide in the blood and body fluids and to and from the cells, Regulation of ventilation and other aspects of respiration: Exercise causes these factors to change, but the body is designed to maintain homeostasisWhen one goes from a state of rest to a state of maximal intensity of exercise, oxygen consumption, carbon dioxide formation, and total pulmonary and alveolar ventilation increase by approximately 20-fold. A linear relationship exists between oxygen consumption and ventilation. At maximal exercise, pulmonary ventilation is 100-110 L/min, whereas maximal breathing capacity is 150-170 L/min. Thus, the maximal breathing capacity is approximately 50% greater than the actual pulmon ary ventilation during maximal exercise. This extra ventilation provides an element of safety that can be called on if the situation demands it (eg, at high altitudes, under hot conditions, abnormality in the respiratory system). Therefore, the respiratory system itself is not usually the most limiting factor in the delivery of oxygen to the muscles during maximal muscle aerobic metabolism. VO2 max is the rate of oxygen consumption under maximal aerobic metabolism. This rate in short-term studies is found to increase only 10% with the effect of training. However, that of a person who runs in marathons is 45% greater than that of an untrained person. This is believed to be partly genetically determined (eg, stronger respiratory muscles, larger chest size in relation to body size) and partly due to long-term training. Oxygen diffusing capacity is a measure of the rate at which oxygen can diffuse from the alveoli into the blood. An increase in diffusing capacity is observed in a state of maximal exercise. This results from the fact that blood flow through many of the pulmonary capillaries is sluggish in the resting state. In exercise, increased blood flow through the lungs causes all of the pulmonary capillaries to be perfused at their maximal level, providing a greater surface area through which oxygen can diffuse into the pulmonary capillary blood. Athletes who require greater amounts of oxygen per minute have been found to have higher diffusing capacities, but the exact reason why is not yet known. Although one would expect the oxygen pressure of arterial blood to decrease during strenuous exercise and carbon dioxide pressure of venous blood to increase far above normal, this is not the case. Both of these values remain close to normal. Stimulatory impulses from higher centers of the brain and from joint and muscle proprioceptive stimulatory reflexes account for the nervous stimulation of the respiratory and vasomotor center that provides almost exactly the pr oper increase in pulmonary ventilation to keep the blood respiratory gases almost normal. If nervous signals are too strong or weak, chemical factors bring about the final adjustment in respiration that is required to maintain homeostasis. Regular exercise makes the cardiovascular system more efficient at pumping blood and delivering oxygen to the exercise muscles. Releases of adrenaline and lactic acid into the blood result in an increase of the heart rate (HR). Basic definitions of terms are as follows:VO2 equals cardiac output times oxygen uptake necessary to supply oxygen to muscles. The Fick equation is the basis for determination of VO2. Exercises increase some of the different components of the cardiovascular system, such as stroke volume (SV), cardiac output, systolic blood pressure (BP), and mean arterial pressure. A greater percentage of the cardiac output goes to the exercising muscles. At rest, muscles receive approximately 20% of the total blood flow, but during exercise, the blood flow to muscles increases to 80-85%. To meet the metabolic demands of skeletal muscle during exercise, 2 major adjustments to blood flow must occur. First, cardiac output from the heart must increase. Second, blood flow from ina ctive organs and tissues must be redistributed to active skeletal muscle. Generally, the longer the duration of exercise, the greater the role the cardiovascular system plays in metabolism and performance during the exercise bout. An example would be the 100-meter sprint (little or no cardiovascular involvement) versus a marathon (maximal cardiovascular involvement). The cardiovascular system helps transport oxygen and nutrients to tissues, transport carbon dioxide and other metabolites to the lungs and kidneys, and distribute hormones throughout the body. The cardiovascular system also assists with thermoregulation.The pumping of blood by the heart requires the following 2 mechanisms to be efficient:Alternate periods of relaxation and contraction of the atria and ventriclesCoordinated opening and closing of the heart valves for unidirectional flow of blood The cardiac cycle is divided into 2 phases: ventricular diastole and ventricular systole.This phase begins with the opening of the atrioventricular (AV) valves. The mitral valve (located between the left atrium and left ventricle) opens when the left ventricular pressure falls below the left atrial pressure, and the blood from left atrium enters the left ventricle.Later, as the blood continues to flow into the left ventricle, the pressure in both chambers tends to equalize.At the end of the di astole, left atrial contractions cause an increase in left atrial pressure, thus again creating a pressure gradient between the left atrium and ventricle and forcing blood into the left ventricle.Ventricular systole begins with the contraction of the left ventricle, which is caused by the spread of an action potential over the left ventricle. The contraction of the left ventricle causes an increase in the left ventricular pressure. When this pressure is higher than the left atrial pressure, the mitral valve is closed abruptly.The left ventricular pressure continues to rise after the mitral valve is closed. When the left ventricular pressure rises above the pressure in the aorta, the aortic valve opens. This period between the closure of the mitral valve and the opening of the aortic valve is called isovolumetric contraction phase.The blood ejects out of the left ventricle and into the aorta once the aortic valve is opened. As the left ventricular contraction is continued, 2 processe s lead to a fall in the left ventricular pressure. These include a decrease in the strength of the ventricular contraction and a decrease in the volume of blood in the ventricle.When the left ventricular pressure falls below the aortic pressure, the aortic valve is closed. After the closure of the aortic valve, the left ventricular pressure falls rapidly as the left ventricle relaxes. When this pressure falls below the left atrial pressure, the mitral valve opens and allows blood to enter left ventricle. The period between the closure of the aortic valve closure and the opening of the mitral valve is called isovolumetric relaxation time. Right-sided heart chambers undergo the same phases simultaneously. Most of the work of the heart is completed when ventricular pressure exists. The greater the ventricular pressure, the greater the workload of the heart. Increases in BP dramatically increase the workload of the heart, and this is why hypertension is so harmful to the heart.Arterial BP is the pressure that is exerted against the walls of the vascular system. BP is determined by cardiac output and peripheral resistance. Arterial pressure can be estimated using a sphygmomanometer and a stethoscope. The reference range for males is 120/80 mm Hg; the reference range for females is 110/70 mm Hg. The difference between systolic and diastolic pressure is called the pulse pressure. The average pressure during a cardiac cycle is called the mean arterial pressure (MAP). MAP determines the rate of blood flow through the systemic circulation.During rest, MAP = diastolic BP + (0.33 X pulse pressure). For example, MAP = 80 + (0.33 X [120-80]), MAP = 93 mm Hg. During exercise, MAP = diastolic BP + (0.50 X pulse pressure). For example, MAP = 80 + (0.50 X [160-80]), MAP = 120 mm Hg. The heart has the ability to generate its own electrical activity, which is known as intrinsic rhythm. In the healthy heart, contraction is initiated in the sinoatrial (SA) node, which is often called the hearts pacemaker. If the SA node cannot set the rate, then other tissues in the heart are able to generate an electrical potential and establish the HR.The parasympathetic nervous system and the sympathetic nervous system affect a personsHR. Parasympathetic nervous system: The vagus nerve originates in the medulla and innervates the SA and AV nodes. The nerve releases ACh as the neurotransmitter. The response is a decrease in SA node and AV node activity, which causes a decrease in HR. Sympathetic nervous system: The nerves arise from the spinal cord and innervate the SA node and ventricular muscle mass. The nerves release norepinephrine as the neurotransmitter. The response is an increase in HR and a force of contraction of the ventricles.At rest, sympathetic and parasympathetic ne rvous stimulation are in balance. During exercise, parasympathetic stimulation decreases and sympathetic stimulation increases. Several factors can alter sympathetic nervous system input.Baroreceptors are groups of neurons located in the carotid arteries, the arch of aorta, and the right atrium. These neurons sense changes in pressure in the vascular system. An increase in BP results in an increase in parasympathetic activity except during exercise, when the sympathetic activity overrides the parasympathetic activity. Chemoreceptors are groups of neurons located in the arch of the aorta and the carotid arteries. These neurons sense changes in oxygen concentration. When oxygen concentration in the blood is decreased, parasympathetic activity decreasesand sympathetic activity increases. Temperature receptors are neurons located throughout the body. These neurons are sensitive to changes in body temperature. As temperature increases, sympathetic activity increases to cool