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Образование Политология Производство Психология Стандартизация Технологии
Exercise 1. What do you know about the human body?
Московский государственный университет имени М.В.Ломоносова
по развитию навыков чтения
и устной речи
Данное учебное пособие предназначено для студентов 2-3 курсов и аспирантов биохимических специальностей биологических факультетов университетов и имеет своей целью дальнейшее совершенствование уже полученных навыков чтения и устной речи. Пособие содержит оригинальные тексты на английском языке, взятые из научных журналов (Science, Scientific American, New Scientist). Тексты и задания, представленные в пособии, рассчитаны на обучающихся продвинутого уровня и содержат задания для обсуждения и вопросы, предполагающие значительный уровень как лингвистической подготовки, так и знаний в сфере биологии.
Данное учебное пособие предназначено для студентов биологического факультета 2-3 курсов и аспирантов биохимического отделения и имеет своей целью совершенствование уже полученных навыков чтения и устной речи. Тексты и задания, представленные в пособии, рассчитаны на обучающихся продвинутого уровня и содержат задания для обсуждения и вопросы, предполагающие значительный уровень как лингвистической подготовки, так и знаний в сфере биологии.
Учебное пособие состоит из 3 разделов (section) по 5 уроков (unit) в каждом в соответствии с возрастанием объема и сложности текстов и заданий. Каждый раздел рассчитан на один семестр, а каждый урок – на 3-4 занятия. Тематическая подборка текстов и их расположение определяются помимо прочего и информированностью студентов: некоторые темы в полном объеме и с достаточным знанием фактического материала они могут обсуждать только к 3 курсу.
Чтение в данном учебном пособии представлено не только как цель, но и как средство обучения, выступая в качестве содержательной базы при совершенствовании навыков говорения. В каждом уроке представлены тексты, направленные на развитие трех основных видов чтения – просмотрового чтения (reading for general information), чтения с выборочным извлечением нужной информации (reading for specific information) и чтения с полным пониманием (reading for detail). После текстов даются задания, развивающие навыки монологического и диалогического высказывания, ведения беседы и аргументации, для совершенствования которых и предназначено учебное пособие. По этой же причине в него не включены упражнения по грамматике. В плане формирования грамматических навыков чтения задачи данного учебного пособия ограничиваются лишь увеличением количества легко распознаваемых грамматических явлений и развитием на этой базе механизма структурной антиципации.
В ходе обучения осуществляется совершенствование умения говорить как в диалогической, так и в монологической форме. При развитии диалогической формы речи акцент сделан на диалоге-обмене мнениями и информацией. При обучении монологической форме речи большое внимание уделяется работе над рассуждением, выражением своего отношения, сравнительной оценкой мнений и позиций, интерпретацией и выражением причинно-следственных связей.
В пособии представлены оригинальные неадаптированные тексты (в некоторых случаях – фрагменты текстов или их сокращенный вариант), взятые из авторитетных научных изданий и их интернет-версий – Nature, Scientific American, New Scientist, а также научной колонки The New York Times. Необходимо отметить, что приведенные в текстах точки зрения зачастую имеют провокационный характер и могут вызвать сильную реакцию учащихся – несогласие, неодобрение и даже полное отрицание заявленных фактов. Некоторые тексты прямо противоречат друг другу. Такая стратегия выбрана автором вполне сознательно и представляется оправданной, поскольку напрямую отвечает целям пособия – на основе прочитанного совершенствовать навыки устной речи, ведения научной дискуссии и аргументации. В задачи автора входило сделать каждый урок учебного пособия познавательным и интересным для студентов всех специальностей, сталкивая альтернативные мнения, и создавая тем самым условия для взаимообогащающего общения.
При отборе текстов пристальное внимание уделялось и их терминологической насыщенности; освоение лексики подчинено методическому принципу «снежного кома», когда лексика предыдущих уроков и текстов снова встречается и отрабатывается в последующих. Некоторые темы также перекликаются друг с другом, и уже проработанные ранее вопросы расширяются в следующих уроках. Так, например, нарушения сна и их причины (урок Sleep) позднее рассматриваются при обсуждении воздействия алкоголя на организм человека (урок Alcohol). Основные термины урока Human Genetics пересекаются с терминами урока Human Evolution.
Каждый урок (unit) открывается эпиграфом, отражающим его основную мысль. В первом упражнении предлагаются вопросы для обсуждения по теме урока (What do you know about…), а также в некоторых уроках даны основные термины, которые студенты должны объяснить.
Разделы различаются не только по объему и степени сложности текстов, но и по их количеству и предлагаемым упражнениям. В первом разделе даются самые простые небольшие тексты, а также упражнения на отработку лексики, которые далее уже не встречаются. Во втором и третьем разделах тексты становятся сложнее и длиннее с нарастающей степенью терминологической насыщенности. Предлагаемые к текстам задания в форме вопросов множественного выбора (multiple choice), вопросов «верно-неверно» (true/false), задания на заполнение пропусков (blank filling) и соотнесение информации (matching information) проверяют умение студентов извлекать информацию из текстов, выявлять причинно-следственные связи, интерпретировать отношение говорящего.
В связи с тем, что учебное пособие полностью построено на аутентичных текстах разного характера, большое значение придается самостоятельному обращению учащихся к словарям и справочным изданиям, тем самым у студентов и аспирантов формируется потребность и развивается умение использования одно- и двуязычной справочной литературы и источников.
Последним заданием каждого урока является составление краткого обзора всех рассмотренных в его рамках вопросов. Данное задание направлено на развитие навыков анализа, реферирования и устных презентаций.
В конце каждого из трех разделов учебного пособия (section) приводится список рекомендуемых тем для устных докладов и презентаций студентов.
Unit 1. Human body ……………………………………………………………………..…..3
Unit 2. Water ………………………………………………………………………………….6
Unit 3. Fungi …………………………………………………………………………………..9
Unit 4. Bacteria ……………………………………………………………………………….12
Unit 5. Domesticated animals …………………………………………………………..…15
Recommended Report and Presentation Topics ………………………………………18
Unit 6. Brain ………………………………………………………………………….…………19
Unit 7. Sleep …………………………………………………………………………………….22
Unit 8. Coffee …………………………………………………………………………………...25
Unit 9. Human Genetics and Diversity …………………………………………….……….28
Unit 10. Animal adaptations ………………………………………………………….………31
Recommended Report and Presentation Topics …………………………………………34
Unit 11. Human Evolution ………………………………………………….……………….35
Unit 12. Alcohol ……………………………………………………………………………….39
Unit 13. Sex and Gender …………………………………………………………………….43
Unit 14. Aging ………………………………………………………………………...……….47
Unit 15. Food ……………………………………………………………………….………….51
Recommended Report and Presentation Topics ………………………………………..57
Unit 1. Human Body
Any lover of humanity who looks back on the achievements of medical science must feel his heart glow and his right ventricle expand with the percardiac stimulus of a permissible pride.
Stephen B. Leacock,Canadian economist and humorist
Exercise 1. What do you know about the human body?
1. How is our body prepared for the physical stresses and wear of human life? Speak about each system of organs.
2. What are the most surprising abilities of the human body?
3. What is the adaptive significance of four-chambered heart and greater and lesser circulation?
4. How does the human body adapt to changes?
5. What medical achievements have most significantly changed human life and health care?
Exercise 3. Now read the text about a unique brain operation.
Exercise 4. The words on this list are all verbs (some of them were used in the text). What are the corresponding noun forms? Write them in the second column. The first one has been done for you as an example.
1. to diagnose - diagnosis
2. to examine - _______________
3. to prescribe - ______________
4. to suffer - _________________
5. to operate - _______________
6. to cure - __________________
7. to recover - _______________
8. to analyse - _______________
9. to infect - _________________
10. to carry - ________________
11. to replace - ______________
12. to degenerate - ___________
13. to paralyse - ______________
14. to treat – _________________
15. to affect – ________________
16. to damage - _______________
Exercise 5. Rewrite the sentences below, changing the verbs (which are in bold) to nouns. Do not change the meaning of the sentences, but be prepared to make grammatical changes if necessary. The first one has been done for you as an example.
Unit 2. Water
Water, thou hast no taste, no color, no odor; canst not be defined, art relished while ever mysterious. Not necessary to life, but rather life itself, thou fillest us with a gratification that exceeds the delight of the senses.
Antoine de Saint-Exupery,The Wisdom of the Sands
Exercise 7. These sentences all give very good advice, but they have been divided into separate halves. Match the half-sentences in Column A with the half-sentences in Column B to make 14 sentences which are correct, complete and true.
Unit 3. Fungi
Every man carries a parasite somewhere.
Read the following two texts (Text A and Text B) to find out.
Unit 4. Bacteria
Soap and water and common sense are the best disinfectants.
Sir William Osler,Canadian physician and Oxford professor of medicine
Exercise 5. Make 15 two-word expressions connected with medical treatment by combining words from the two lists: A and B. Then match each expression with the appropriate phrase below. The first one has been done for you as an example.
1. A condition in which the heart has a reduced blood supply because one of the arteries becomes blocked by a blood clot, causing myocardial ischaemia and myocardial infarction (heart attack)
2. A substance given to make someone lose consciousness so that a major surgical operation can be carried out
3. Soft tissue in cancellous bone.
4. The treatment of disease or other condition by surgery.
5. Any one of the first twenty teeth which develop in children between about six months and two-and-a-half years of age, and are replaced by the permanent teeth at around the age of six.
6. Surgery to repair damaged or malformed parts of the body.
7. A condition in which the nerves in the brain stem have died, and the person can be certified as dead, although the heart may not have stopped beating.
8. The way in which a doctor behaves towards a patient, especially a patient who is in bed.
9. An effect produced by a substance to which a person has an allergy, such as sneezing or a skin rash.
10. A trial carried out in a medical laboratory on a person or on tissue from a person.
11. A tumour which is cancerous and can grow again or spread into other parts of the body, even if removed surgically.
12. A doctor who provides first-line medical care for all types of illness to people who live locally, refers them to hospital if necessary and encourages health promotion.
13. The rhythm of daily activities and bodily processes such as eating, defecating or sleeping, frequently controlled by hormones, which repeats every twenty-four hours.
14. The set of organs such as the stomach, liver and pancreas which are associated with the digestion of food.
15. A diet that provides all the nutrients needed in the correct proportions.
The Tragedy of King Richard the Third
I have known the horse in war and in peace, and there is no place where a horse is comfortable. The horse has too many caprices, and he is too much given to initiative. He invents too many ideas. No, I don’t want anything to do with a horse.
Exercise 2. Read the following two texts (Text A and Text B) about domestication of dogs and goats to check your answers in Exercise 1.
Text A. The Origin of Dogs
Where did our best friend originate? Researchers are looking to DNA to dig up answers about where, when and why pooches became popular
By Katherine Harmon
From Chihuahua to Great Danes, all domestic dogs (Canis familiaris) seem to be descended from the Eurasian gray wolf (Canis lupis). But what we still don't know is exactly when and where our best friends transformed from predators into partners. And such knowledge might help solve the long-disputed question of exactly why dogs were the first animal to be domesticated.
The dog genome was first decoded in 2005—and even before that researchers had been using genetic tools to track Fido's first home. Early research pointed toward east Asia as the locus of first taming after the discovery of high genetic diversity and other key markers in dog populations from various villages there. Some investigators, however, have since pointed out that the genetic search sampled more east Asian village dogs, neglecting similar pups roaming other villages around the globe. That's where the Village Dog Genetic Diversity Project at Cornell University comes in. Starting with a recent genetic analysis of dogs in African villages, the Cornell group hopes ultimately to create a detailed DNA-based map of canine ancestry worldwide, which in turn should provide a new understanding of the ancient humans who took them in.
One part of that new insight appeared earlier this month in the Proceedings of the National Academy of Sciences (PNAS), in a study that calls into question the assumption of dogs' east Asian origin. A team led by Adam Boyko, a researcher at Cornell's Carlos D. Bustamante Lab, sampled 318 village dogs in Africa (as well as hundreds of dogs from North America and Europe for comparison) and discovered that the high genetic diversity of canines there resembles that found in east Asia. "We found almost without exception they're descended from different ancestral populations," Boyko says of the village dogs sampled in Africa. That means they may have been there just as long as others had been in east Asia.
Researchers have also yet to figure out when people first began raising dogs. The going theory is that dogs were domesticated somewhere between 15,000 and 40,000 years ago. But, Boyko explains, genetic testing has not gone deep enough to come up with a more refined date. To try to track down some more clues, field crews have fanned out around the globe this summer to test village dogs in Vietnam, New Guinea, Malaysia and other locations in Eurasia in order to get more data.
Of course, scrappy village dogs aren't often the focus of heartfelt conservation efforts, and some even face active elimination programs. But these pups also have challenges from newly arrived European-descent dogs, which threaten to make a splash in the regional gene pool. "It is unclear the degree to which older populations will be able to maintain their genetic identity and persist in the face of modernity," Boyko and his co-authors wrote in the PNAS paper. So time is of the essence in digging up a solid answer about doggie descent.
Looking back into the pooch family tree will help researchers learn more not only about dogs, but about ancient people, as well. A genetic map of dog domestication could reveal important information about human migration and trade routes. "We may be able to turn dogs into a genetic marker for what human populations were doing," Boyko says. He adds that he and his colleagues also plan to "look for which regions of the genome went under selection earliest," and from that "we'll also learn what traits were selected for at that time." That knowledge, along with a little help from archaeologists, may be able to uncover sniff out just why the dog was so special and became most likely the first domesticated species. (From Scientific American Online, August 20, 2009)
Exercise 4. Divide into two groups. Each group should read either Text A or Text B on domestication of wild horses. In pairs, share your information with your partner and discuss both texts to combine all the details, so you could answer the questions in Exercise 5.
Unit 6. Brain
I’ll give you my opinion of the human race . . . Their heart’s in the right place, but their head is a thoroughly inefficient organ.
W. Somerset Maugham
It is good to rub and polish our brains against that of others.
Michel de Montaigne
METHOD 1: EXERCISE
Mice that run on wheels increase the number of neurons in their hippocampus and perform better on tests of learning and memory. Studies of humans have revealed that exercise can improve the brain’s executive functions (planning, organizing, multitasking, and more). Exercise is also well known for its mood-boosting effects, and people who exercise are less likely to get dementia as they age. Among those who are already aged, athletic senior citizens have better executive function than do those who are sedentary; even seniors who have spent their entire lives on the couch can improve these abilities just by starting to move more in their golden years. You don’t need to be Chuck Norris (thankfully) to get the brain benefits of exercise. Studies of senior citizens have shown that as little as 20 minutes of walking a day can do the trick.
A variety of mechanisms might be responsible for this brain boost. Exercise increases blood flow to the brain, which also increases the delivery of oxygen, fuel and nutrients to those hard-working neurons. Research has shown that exercise can increase levels of a substance called brain-derived neurotrophic factor (BDNF), which encourages growth, communication and survival of neurons. Exercise also improves sleep quality, a pile of studies suggests. And immune function. Is there anything it can’t do?
METHOD 2: DIET
The brain needs fuel just as the body does. So what will really boost your brainpower, and what will make you lose your mind? Saturated fat, that familiar culprit, is no better for the brain than it is for the body. Rats fed diets high in saturated fat underperformed on tests of learning and memory, and humans who live on such diets seem to be at increased risk for dementia.
Not all fat is bad news, however. The brain is mostly fat—all those cell membranes and myelin coverings require fatty acids—so it is important to eat certain fats, particularly omega-3 fats, which are found in fish, nuts and seeds. Alzheimer’s disease, depression, schizophrenia and other disorders may be associated with low levels of omega-3 fatty acids. It is especially important that babies get enough fat. Babies who don’t get enough of the stuff have trouble creating the fatty myelin insulation that helps neurons transmit signals. Luckily for babies, breast milk is 50 percent fat.
Fruits and vegetables also appear to be brain superfoods. Produce is high in substances called antioxidants, which counteract atoms that can damage brain cells. Researchers have found that high-antioxidant diets keep learning and memory sharp in aging rats and even reduce the brain damage caused by strokes. That’s food for thought.
It’s not just what you eat that affects the brain. It’s also how much. Research has shown that laboratory animals fed calorie-restricted diets—anywhere from 25 to 50 percent less than normal—live longer than other animals do. And it turns out they also have improved brain function, performing better on tests of memory and coordination. Rodents on calorie-restricted diets are also better able to resist the damage that accompanies Alzheimer’s, Parkinson’s and Huntington’s disease.
METHOD 3: STIMULANTS
Stimulants are substances that rev up the nervous system, increasing heart rate, blood pressure, energy, breathing and more. Caffeine is probably the most famous of the group. (It is actually the most widely used “drug” in the world.) By activating the central nervous system, caffeine boosts arousal and alertness. Although high doses of caffeine can undoubtedly have unpleasant effects (ranging from irritability, anxiety and insomnia to the most unpleasant of all: death in rare cases), small to moderate amounts can boost our mental functioning in ways researchers are now measuring. One study showed that the equivalent of two cups of coffee can boost short-term memory and reaction time. Functional MRI scans taken during the study also revealed that volunteers who had been given caffeine had increased activity in the brain regions involving attention. In addition, research suggests caffeine can protect against age-related memory decline in older women. But try to limit yourself to fewer than 100 cups a day. That much coffee contains about 10 grams of caffeine, enough to cause fatal complications.
Cocaine and amphetamines are less benign. Although they work on the brain through different mechanisms, they have similar effects. Taking them increases the release of some of the brain’s feel-good neurotransmitters—including dopamine and serotonin—and produces a rush of euphoria. They also increase alertness and energy. That all sounds pretty good, but cocaine and amphetamines are extremely addictive drugs and in high doses they can cause psychosis and withdrawal. The withdrawal symptoms are nasty and can lead to depression, the opposite of that euphoric feeling. And of course, an overdose can kill you.
METHOD 4: VIDEO GAMES
Video games could save your life. Surgeons who spend at least a few hours a week playing video games make one-third fewer errors in the operating room than nongaming doctors do. Indeed, research has shown that video games can improve mental dexterity, while boosting hand-eye coordination, depth perception and pattern recognition. Gamers also have better attention spans and information-processing skills than the average Joe has. When nongamers agree to spend a week playing video games (in the name of science, of course), their visual-perception skills improve. And strike your notions of gamers as outcasts: one researcher found that white-collar professionals who play video games are more confident and social.
Of course, we cannot talk about the effects of video games without mentioning the popular theory that they are responsible for increasing real-world violence. A number of studies have reinforced this link. Young men who play a lot of violent video games have brains that are less responsive to graphic images, suggesting that these gamers have become desensitized to such depictions. Another study revealed that gamers had patterns of brain activity consistent with aggression while playing first-person shooter games. This does not necessarily mean these players will actually be violent in real life. The connections are worth exploring, but so far the data do not support the idea that the rise of video games is responsible for increased youth violence.
METHOD 5: MUSIC
When you turn on Queen’s Greatest Hits, the auditory cortex analyzes the many components of the music: volume, pitch, timbre, melody and rhythm. But there’s more to music’s interaction with the brain than just the raw sound. Music can also activate your brain’s reward centers and depress activity in the amygdala, reducing fear and other negative emotions. A highly publicized study suggested that listening to Mozart could boost cognitive performance, inspiring parents everywhere to go out and buy classical CDs for their children. The idea of a “Mozart effect” remains popular, but the original study has been somewhat discredited, and any intellectual boost that comes from listening to music seems to be tiny and temporary. Nevertheless, music does seem to possess some good vibrations. It can treat anxiety and insomnia, lower blood pressure, soothe patients with dementia, and help premature babies to gain weight and leave the hospital sooner.
Music training can bolster the brain. The motor cortex, cerebellum and corpus callosum are all bigger in musicians than in nonmusicians. And string players have more of their sensory cortices devoted to their fingers than do those who don’t play the instruments. There is no agreement yet on whether musical training makes you smarter, but some studies have indeed shown that music lessons can improve the spatial abilities of young kids.
METHOD 6: MEDITATION
Meditation, or the turning of the mind inward for contemplation and relaxation, seems to help all types of conditions—anxiety disorders, sure, but it can also reduce pain and treat high blood pressure, asthma, insomnia, diabetes, depression and even skin conditions. And regular meditators say they feel more at ease and more creative than nonmeditators do. Researchers are now illuminating the actual brain changes caused by meditation by sticking meditators into brain-imaging machines. For one, although the brain’s cells typically fire at all different times, during meditation they fire in synchrony. Expert meditators also show spikes of brain activity in the left prefrontal cortex, an area of the brain that has generally been associated with positive emotions. And those who had the most activity in this area during meditation also had big boosts in immune system functioning.
Meditation can increase the thickness of the cerebral cortex, particularly in regions associated with attention and sensation. (The growth does not seem to result from the cortex growing new neurons, though—it appears that the neurons already there make more connections, the number of support cells increases, and blood vessels in that area get bigger.) (From Scientific American, February, 2009)
Unit 7. Sleep
Sleep covers a Man all over, Thoughts and all, like a Cloak; ’tis Meat for the Hungry, Drink for the Thirsty, Heat for the Cold, and Cold for the Hot.
Miguel de CervantesDon Quixote
Sleep remains one of the great mysteries of modern neuroscience. We spend nearly one-third of our lives asleep, but the function of sleep still is not known. Fortunately, over the last few years researchers have made great headway in understanding some of the brain circuitry that controls wake-sleep states. Scientists now recognize that sleep consists of several different stages; that the choreography of a night’s sleep involves the interplay of these stages, a process that depends upon a complex switching mechanism; and that the sleep stages are accompanied by daily rhythms in bodily hormones, body temperature and other functions.
Sleep disorders are among the nation’s most common health problems, affecting up to 70 million people, most of whom are undiagnosed and untreated. These disorders are one of the least recognized sources of disease, disability and even death, costing an estimated $100 billion annually in lost productivity, medical bills and industrial accidents. Research holds the promise for devising new treatments to allow millions of people to get a good night’s sleep.
Why Do We Sleep?
By C. Claiborne Ray
“Sleep has many functions, and most of us think the main functions are not for the body but for the brain,” said Dr. Arthur Spielman, a sleep expert at City College of New York. “But,” he added, “you are talking to a brain scientist, and it depends on whom you ask.’’
The reason sleep occurs in the first place is tied to both mental and physiological cycles that evolved on a planet with a 24-hour cycle of light and dark, Dr. Spielman said. The internal biological clocks that developed in living things, from single cells to humans, allow them to anticipate the transitions from light to dark and from dark to light, so that they are ready for the functions appropriate to light, like metabolism and photosynthesis, and for those suited to darkness. “A physiologist might say sleep was to avoid wasting metabolic energy in the dark,’’ he said. “But a brain scientist would say that glycogen, the only fuel for the brain, is depleted during waking and restored during sleep.”
Sleep is useful for restoring particular parts of the brain that are quiet during sleep and return to functioning during waking, like the areas involved in attention, alertness and memory. Sleep is also important for regulating the timing of hormones under the control of the brain, Dr. Spielman said, like cortisol, the stress-response hormone, which is suppressed at the beginning of sleep and ramps up in anticipation of waking, and growth hormone, which is secreted at night during sleep characterized by slow brain waves. (August 15, 2006 NY Times)
Exercise 3. Read the chapter about sleep taken from the book Brain Facts: a Primer on the Brain and Nervous System, 2002 to check your answers in Exercise 1.
The Stuff of Sleep
Sleep appears to be a passive and restful time when the brain is less active. In fact, this state actually involves a highly active and well-scripted interplay of brain circuits to produce the stages of sleeping.
The stages of sleep were discovered in the 1950s in experiments examining the human brain waves or electroencephalogram (EEG) during sleep. Researchers also measured movements of the eyes and the limbs during sleep. They found that over the course of the first hour or so of sleep each night, the brain progresses through a series of stages during which the brain waves progressively slow down. The period of slow wave sleep is accompanied by relaxation of the muscles and the eyes. Heart rate, blood pressure and body temperature all fall. If awakened at this time, most people recall only a feeling or image, not an active dream.
Over the next half hour or so, the brain emerges from the deep slow wave sleep as the EEG waves become progressively faster. Similar to during waking, rapid eye movements emerge, but the body’s muscles become almost completely paralyzed (only the muscles that allow breathing remain active). This state is often called rapid eye movement (REM) sleep. During REM sleep, there is active dreaming. Heart rate, blood pressure and body temperature become much more variable. The first REM period usually lasts ten to 15 minutes.
Over the course of the night, these alternative cycles of slow wave and REM sleep alternate, with the slow wave sleep becoming less deep, and the REM periods more prolonged, until waking occurs.
Over the course of a lifetime, the pattern of sleep cycles changes. Infants sleep up to 18 hours per day, and they spend much more time in deep slow wave sleep. As children mature, they spend less time asleep, and less time in deep slow wave sleep. Older adults may sleep only six to seven hours per night, often complain of early wakening that they cannot avoid, and spend very little time in slow wave sleep.
The most common sleep disorder, and the one most people are familiar with, is insomnia. Some people have difficulty falling asleep initially, but other people fall asleep, and then awaken part way through the night, and cannot fall asleep again. Although there are a variety of short-acting sedatives and sedating antidepressant drugs available to help, none of these produces a truly natural and restful sleep state because they tend to suppress the deeper stages of slow wave sleep.
Excessive daytime sleepiness may have many causes. The most common are disorders that disrupt sleep and result in inadequate amounts of sleep, particularly the deeper stages. These are usually diagnosed in the sleep laboratory. Here, the EEG, eye movements and muscle tone are monitored electrically as the individual sleeps. In addition, the heart, breathing, and oxygen content of the blood can be monitored.
Obstructive sleep apnea causes the airway muscles in the throat to collapse as sleep deepens. This prevents breathing, which causes arousal, and prevents the sufferer from entering the deeper stages of slow wave sleep. This condition can also cause high blood pressure and may increase the risk of heart attack. There is also an increased risk of daytime accident, especially automobile accidents, which may prevent driving. Treatment is complex and may include a variety of attempts to reduce airway collapse during sleep. While simple things like losing weight, avoiding alcohol and sedating drugs prior to sleep, and avoiding sleeping on one’s back can sometimes help, most people with sleep apnea require positive airway pressure to keep the airway open. This can be provided by fitting a small mask over the nose that provides an air stream under pressure during sleep. In some cases, surgery is needed to correct the airway anatomy.
Periodic limb movements of sleep are intermittent jerks of the legs or arms, which occur as the individual enters slow wave sleep, and can cause arousal from sleep. Other people have episodes in which their muscles fail to be paralyzed during REM sleep, and they act out their dreams. This REM behavior disorder can also be very disruptive to a normal nights’ sleep. Both disorders are more common in people with Parkinson’s disease, and both can be treated with drugs that treat Parkinson’s, or with an anti-epileptic drug called clonazepam.
Narcolepsy is a relatively uncommon condition (one case per 2,500 people) in which the switching mechanism for REM sleep does not work properly. Narcoleptics have sleep attacks during the day, in which they suddenly fall asleep. This is socially disruptive, as well as dangerous, for example, if they are driving. They tend to enter REM sleep very quickly as well, and may even enter a dreaming state while still awake, a condition known as hypnagogic hallucinations. They also have attacks during which they lose muscle tone, similar to what occurs during REM sleep, but while they are awake. Often, this occurs while they are falling asleep or just waking up, but attacks of paralysis known as cataplexy can be triggered by an emotional experience or even hearing a funny joke.
Recently, insights into the mechanism of narcolepsy have given major insights into the processes that control these mysterious transitions between waking, slow wave and REM sleep states. (From Brain Facts: a Primer on the Brain and Nervous System, 2002)
Exercise 4. Work in small groups. Write out from the text 15 key word combinations which will help you to retell the text and explain your choice. Then together agree on the final list of word combinations.
Unit 8. Coffee
In the cauldron boil and bake;
Eye of newt and toe of frog,
Wool of bat and tongue of dog,
Adder’s fork and blind-worm’s sting,
Lizard’s leg and howlet’s wing. . .
From a drop of water. . . a logician could infer the possibility of an Atlantic or a Niagara without having seen or heard of one or the other. So all life is a great chain, the nature of which is known whenever we are shown a single link of it.
Sir Arthur Conan DoyleA Study in Scarlet
Exercise 1. What do you know about genetics? Explain the following terms in English:
Exercise 2. Discuss the following questions about genetic diversity of humans:
Exercise 3. Read the following two texts (Text A and Text B) about current genetic research of population diversity to check your answers in Exercise 2.
Exercise 1. What do you know about diversity of animals and their adaptations?
1. Why are animals classified into a separate Kingdom?
2. What are the basic taxonomic differences between the main classes of animals?
3. What basic adaptations have animals developed to different environments where animal live?
4. What environments can animals never adapt to? Why? Are there other organisms that can live there?
5. What is the role of species diversity in the stability of ecosystem?
6. What role do parasites and predators play in keeping biodiversity?
Exercise 2. You are going to read a text about bird migrations. The following figures will be used in the text. What do you think they refer to?
• 30,000 km • 100 hours • 500 beats • 9000 m • 21 grams
Exercise 3. Now read the text to check your answers.
Have Wings, Will Travel: Avian Adaptations to Migration
By Mary Deinlein
Flight affords the utmost in mobility and has made possible the evolution of avian migration as a means of exploiting distant food resources and avoiding the physiological stress associated with cold weather. Variations in the patterns of migration are nearly as numerous as the birds that migrate. While some species move only a few kilometers up and down mountain slopes, others will travel hundreds or even thousands of kilometers, often traversing vast bodies of water or tracts of inhospitable terrain.
One record holder in long-distance travel is the Arctic Tern (Sterna paradisaea), which makes an annual round-trip of about 30,000 kilometers between opposite ends of the globe, from Arctic breeding grounds to Antarctic seas. This feat is possible because terns are adapted for feeding at sea, allowing them to refuel en route. Even more amazing are the aerial voyages of the landbirds and shorebirds whose transoceanic flights must be accomplished non-stop. The Pacific Golden-Plover (Pluvialis fulva) flies continuously for more than 100 hours to travel the 5,000- to 7,000-kilometer distance from northern Siberia and Alaska to Hawaii and other islands in the Pacific Ocean.
The Blackpoll Warbler's (Dendroica striata) over-water flight from the coast of New England or southern Canada to South America keeps it aloft for 80 to 90 continuous hours over a distance of 3,000 to 4,000 kilometers, an effort which researchers Tim and Janet Williams conclude "requires a degree of exertion not matched by any other vertebrate; in man the metabolic equivalent would be to run a 4 minute mile for 80 hours. Even the tiny Ruby-throated Hummingbird (Archilochus colubris), weighing only about as much as a penny, makes the 1,000-kilometer, 24-hour spring flight across the Gulf of Mexico from the Yucatan Peninsula to the southern coast of the United States.
So how do they do it? What specialized adaptations allow birds to accomplish such prodigious feats of endurance?
To understand how superbly adapted birds are to their highly mobile way of life, one must first consider the quintessential characteristics that distinguish birds from all other animals. Feathers, the trademark of the Class Aves, provide the insulation necessary to maintain a high "engine" (body) temperature, ranging from 107 to 113 degrees F across species. Additionally the long feathers of the wings act as airfoils which help generate the lift necessary for flight. Well-developed pectoral muscles power the flapping motion of the wings. A streamlined body shape and a lightweight skeleton composed of hollow bones minimize air resistance and reduce the amount of energy necessary to become and remain airborne.
Keeping the hard-running avian engine running smoothly requires super-efficient circulatory and respiratory systems. Birds have a large, four-chambered heart which proportionately weighs six times more than a human heart. This, combined with a rapid heartbeat (the resting heart rate of a small songbird is about 500 beats per minute; that of a hummingbird is about 1,000 beats per minute) satisfies the rigorous metabolic demands of flight. The avian respiratory system—the most efficient in the animal kingdom—consists of two lungs plus special air sacs, and takes up 20% of a bird's volume compared to 5% in a human. Unlike mammalian or reptilian lungs, the lungs of birds remain inflated at all times, with the air sacs acting as bellows to provide the lungs with a constant supply of fresh air.
In addition to these general avian characteristics, migratory birds exhibit a suite of specialized traits. Migrants generally have longer, more pointed wings than non-migratory species, a feature which further minimizes air resistance. Also, the pectoral muscles of migrants tend to be larger and composed of fibers which are more richly supplied with nutrient- and oxygen-carrying blood vessels and energy-producing mitochondria, making the pectoral muscles of migrants especially efficient at energy production and use.
Many migrants face the additional challenge of flying at high altitudes. Most songbirds migrate at 500 to 2,000 meters, but some fly as high as 6,800 meters; swans have been recorded at 8,000 meters and Bar-headed Geese (Anser indica) flying over the Himalayas at 9,000 meters. Accounting for their ability to withstand the low levels of oxygen available at such altitudes, the blood of migratory birds is characterized by two specialized adaptations. The oxygen-carrying capacity of the blood is enhanced by a high concentration of red blood cells. Secondly, instead of one form of hemoglobin in the red blood cells as is typical in non-migrants and other classes of vertebrates, some migratory birds possess two forms of hemoglobin which differ in their oxygen carrying and releasing capacities. This guarantees an adequate oxygen supply over a wide range of altitudes and allows birds to adapt rapidly to varying levels of oxygen availability.
Preparing for take-off
Migrants change rapidly into a "superbird state" in preparation for migration. This transformation is triggered by an internal annual "clock," which is set by day length and weather.
When it comes to fueling migration, fat is where it's at. Fat is not only lighter and less bulky than carbohydrates or protein, but also supplies twice as much energy. Not surprisingly, then, preparation for migration entails a rapid weight gain program geared to increasing fat reserves. This program combines both behavioral and physiological changes. A dramatic increase in appetite and food consumption, termed hyperphagia, begins about two to three weeks before migration and persists throughout the migratory period. Accompanying this veritable feeding frenzy is an increase in the efficiency of fat production and storage. As a result, a migratory bird can increase its body weight through fat deposition by as much as 10% per day (usually 1-3%). Additionally, in birds that are in migratory disposition, the pectoral muscles become larger and well supplied with enzymes necessary for the oxidation, or "burning," of fat.
Longer migration distances require greater amounts of fat. Non-migratory passerines maintain a "fat load" of about 3-5% of their lean body weight. In preparation for migration, short- and medium-distance migratory songbirds attain a fat load of between 10 and 25%, while long-distance migrants reach fat loads of 40 to 100%. Maximum fat loads are attained just prior to flights over major topographic barriers, such as deserts, high mountains, or large bodies of water. A typical Blackpoll Warbler at the end of its breeding season weighs about 11 grams, equivalent to the weight of four pennies. In preparing for its transatlantic trek, it may accumulate enough fat reserves to increase its body weight to 21 grams.
Readiness for migration entails other behavioral modifications. Before migrating in the fall, many migrants which ordinarily eat insects will switch to a diet of berries and other fruits. At this time when food intake needs are increasing and insect numbers are decreasing, fruits are abundant and high in carbohydrates and lipids which are readily converted to fat. Many migrants that typically are not gregarious will flock together prior to, or during, migration. This social behavior may result in improved predator avoidance, food finding, and orientation. Some species also fly in formation, a strategy that improves aerodynamics and reduces energy expenditure.
A radical shift from being active exclusively during the day to migrating at night occurs in many species during migration, including most shorebirds and songbirds. Possible advantages to flying at night include decreased vulnerability to predators, reduced threat of dehydration or overheating, a greater likelihood of encountering favorable winds and a stable air mass (rising hot air and more variable wind directions occur during the daytime), and time during the day to forage.
Migratory birds kept in captivity exhibit behavior termed Zugunruhe, or migratory restlessness. This behavior, characterized by rapid fluttering of the wings while perching, begins at the same time that conspecifics (individuals of the same species) in the wild are setting off on migration, and persists for the same length of time required for the wild counterparts to complete their migration. The captive birds even orient themselves in the appropriate direction in which they would be migrating. Over the past 15 years, this behavior has allowed researchers to demonstrate experimentally that many of the important physical and behavioral correlates to migration are under at least partial genetic control. For instance, when migratory Blackcaps (Sylvia atricapilla ) were mated with non-migratory individuals of the same species, 30% of the offspring exhibited Zugunruhe. When individuals which displayed high levels of Zugunruhe, consistent with their long migratory routes, were bred with conspecifics with short migration routes, the offspring displayed intermediate levels of Zugunruhe. The results from these and other cross-breeding experiments support the hypothesis that migration and its associated patterns—such as distance and timing—are inherited traits, at least in some species. These experiments apply to species with relatively fixed migration routes. Many species have facultative migration patterns, moving only when food supply is low, or when weather turns bad. Research has shown that access to food for these species greatly affects Zugunruhe.
Despite this advanced understanding of some of the mechanisms behind avian migrations, the annual odysseys of billions of birds remain one of the most mysterious and amazing phenomena in the animal world.
Unit 11. Human Evolution
The species does not grow into perfection: the weak again and again get the upper hand of the strong,—their large number, and their greater cunning are the cause of it.
Unit 12. Alcohol
We drink one another’s health and spoil our own.
Jerome K. Jerome
How long is its history?
4000BC - Wine and beer making in Egypt and Sumeria
3500BC - Bronze-age vessels show evidence of wine consumption in eastern Mediterranean
800BC - Distillation of spirits in India
AD625 - Mohammed orders his followers to abstain from alcohol
1850s - New York bartenders invent the cocktail
1920-33 - Prohibition in the US. Alcohol was also illegal in Finland from 1919 to 1932 and in various Canadian provinces at various times between 1900 and 1948.
Exercise 3. Now read more detailed information about the effects of alcohol on the brain provided by Anthony Dekker D.O., Director of Ambulatory Care and Community Health at Phoenix Indian Medical Center.
Drink to Your Health?
By Arthur L. Klatsky
Three decades of research shows that drinking small to moderate amounts of alcohol has cardiovascular benefits. A thorny issue for physicians is whether to recommend drinking to some patients.
America has always had trouble deciding whether alcohol is a bad thing or a good thing. Millions who remember Prohibition, when all alcoholic beverages were illegal, now witness a constant stream of advertisements from producers of alcoholic beverages encouraging people to drink. Despite alcohol’s popularity today, however, many still consider abstinence a virtue. Certainly, heavy drinking and alcoholism deserve deep concern for the terrible toll they take on alcohol abusers and society in general. But worry about the dangers of abuse often leads to emotional denials that alcohol could have any medical benefits. Such denials ignore a growing body of evidence indicating that moderate alcohol intake wards off certain cardiovascular conditions, most notably heart attacks and ischemic strokes (those caused by blocked blood vessels). A few studies even show protection against dementia, which can be related to cardiovascular problems.
The Alcohol Effect
A discussion of moderate drinking requires a working definition of “moderate.” Simple definitions of light, moderate or heavy are somewhat arbitrary, but a consensus in the medical literature puts the upper limit for moderate drinking at two standard-size drinks a day. Studies show that drinking above that level can be harmful to overall health, although sex, age and other factors lower and raise the boundary for individuals.
The main medical benefit of reasonable alcohol use seems to be a lowering of the risk for coronary heart disease (CHD), which results from the buildup of atherosclerosis (fatty plaque) in the arteries. Atherosclerosis restricts blood flow to the heart and can promote the formation of vessel-blocking clots. It can thereby cause angina (chest discomfort resulting from low oxygen levels in the heart muscles), heart attack (the death of heart tissue that occurs when a blood clot or narrowing of the arteries prevents blood from reaching the heart) and death, often without warning. The condition usually starts at a young age but takes decades to blossom into overt CHD. The most common form of heart disease in developed countries, CHD causes about 60 percent of deaths from cardiovascular ills and about 25 percent of all deaths in those nations.
Pathologists uncovered the first clues to the value of alcohol in the early 1900s, noting that the large arteries of people who died of alcoholic liver cirrhosis seemed remarkably “clean”—that is, free of atherosclerosis. One explanatory hypothesis assumed that alcohol was a nebulous solvent, essentially dissolving the buildup in the arteries; another explanation held that heavier drinkers died before their atherosclerosis had a chance to develop. Neither idea truly explained drinkers’ unblocked arteries, however.
A more telling hint emerged in the late 1960s, when Gary D. Friedman of the Kaiser Permanente Medical Center in Oakland, Calif., came up with a novel idea: use computers to unearth unknown predictors of heart attacks. The power of computing could first identify healthy people who had risk factors similar to heart attack victims. Such factors include cigarette smoking, high blood pressure, diabetes, elevated levels of low-density lipoprotein (LDL, or “bad”) cholesterol, low levels of high-density-lipoprotein (HDL, or “good”) cholesterol, male gender, and a family history of CHD. Friedman then searched for predictors of heart attacks by comparing the patients and the newly found controls in hundreds of ways—for example, their exercise and dietary habits and their respective levels of various blood compounds. The computers spit out a surprising discovery: abstinence from alcohol was associated with a higher risk of heart attack.
Since then, dozens of investigations in men and women of several racial groups in various countries have correlated previous alcohol use with current health. These studies have firmly established that nondrinkers develop both fatal and nonfatal CHD more often than do light to moderate drinkers. In addition, in 2000 Giovanni Corrao of the University of Milan-Bicocca in Italy, Kari Poikolainen of the Järvenpää Addiction Hospital in Finland and their colleagues combined the results of 28 previously published investigations on the relation between alcohol intake and CHD. In this meta-analysis, they found that the risk of developing CHD went down as the amount of alcohol consumed daily went up from zero to 25 grams. At 25 grams—the amount of alcohol in about two standard drinks—an individual’s risk of a major CHD event, either heart attack or death—was 20 percent lower than it was for someone who did not drink at all. New data about alcohol protecting against death from CHD are even more impressive. At a meeting of the American Heart Association last November, it was announced that those who had one or two alcoholic drinks a day had a 32 percent lower risk of dying from CHD than abstainers did.
The possible mechanisms by which alcohol has such an apparently profound effect on cardiovascular health primarily involve cholesterol levels and blood clotting. Blood lipids play a central role in CHD. Numerous stud
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