Book 1 Reading and Speaking (1108795), страница 2
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(That man lived for more than three years before ultimately succumbing to cancer.) The procedure isamong the most drastic kinds of brain surgery—"You can't take more than half. If you take the whole thing, you'vegot a problem," Johns Hopkins neurologist John Freeman quips.One side effect Canadian neurosurgeon Kenneth McKenzie reported in 1938 after a hemispherectomy on a16-year-old girl who suffered a stroke was that her seizures stopped. Nowadays, the surgery is performed onpatients who suffer dozens of seizures every day that resist all medication, and which are due to conditions thatmostly affect one hemisphere.
"These disorders are often progressive and damage the rest of the brain if nottreated," University of California, Los Angeles, neurosurgeon Gary Mathern says. Freeman concurs:"Hemispherectomy is something that one only does when the alternatives are worse."Anatomical hemispherectomies involve the removal of the entire hemisphere, whereas functionalhemispherectomies only take out parts of a hemisphere, as well as severing the corpus callosum, the fiber bundlethat connects the two halves of the brain. The evacuated cavity is left empty, filling with cerebrospinal fluid in a dayor so. The strength of anatomical hemispherectomies, a specialty of Hopkins, lies in the fact that "leaving even alittle bit of brain behind can lead seizures to return," Freeman says. On the other hand, functionalhemispherectomies, which U.C.L.A.
surgeons usually perform, lead to less blood loss. "Our patients are usuallyunder two years of age, so they have less blood to lose," Mathern says. Most Hopkins hemispherectomy patientsare five to 10 years old.Neurosurgeons have performed the operation on children as young as three months old. Astonishingly,memory and personality develop normally.
A recent study found that 86 percent of the 111 children who underwenthemispherectomy at Hopkins between 1975 and 2001 are either seizure-free or have nondisabling seizures that donot require medication. The patients who still suffer seizures usually have congenital defects or developmentalabnormalities, where brain damage is often not confined to just one hemisphere, Freeman explains. Another studyfound that children that underwent hemispherectomies often improved academically once their seizures stopped."One was champion bowler of her class, one was chess champion of his state, and others are in college doing verynicely," Freeman says.Of course, the operation has its downside: "You can walk, run—some dance or skip—but you lose use of thehand opposite of the hemisphere that was removed.
You have little function in that arm and vision on that side islost," Freeman says. Remarkably, few other impacts are seen. If the left side of the brain is taken out, "most peoplehave problems with their speech, but it used to be thought that if you took that side out after age two, you'd nevertalk again, and we've proven that untrue," Freeman says. "The younger a person is when they undergohemispherectomy, the less disability you have in talking.
Where on the right side of the brain speech is transferredto and what it replaces is something nobody has really worked out."Mathern and his colleagues have recently conducted the first functional magnetic resonance imaging studyinto hemispherectomy patients, investigating how their brain changes with physical rehabilitation. Probing how theremaining cerebral hemispheres of these patients acquire language, sensory, motor and other functions "couldshed a great deal of light on the brain's plasticity, or ability to change," Freeman notes. Still, having half a brain—and therefore only the use of one hand and half a field of vision in each eye—is a condition most would prefer toavoid.
(From Scientific American Online, May 24, 2007)Exercise 4. The words on this list are all verbs (some of them were used in the text). What are thecorresponding noun forms? Write them in the second column. The first one has been done for you as anexample.1. to diagnose - diagnosis2. 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 changethe meaning of the sentences, but be prepared to make grammatical changes if necessary.
The first onehas been done for you as an example.1. I diagnosed that the patient had a heart condition.1. My diagnosis was that the patient had a heartcondition.72. I examined the patient fully.3. I prescribed a course of antibiotics.4. He suffered very little.5.
Ten per cent of the population are thought to carry thebacteria.6. This disease cannot be cured.7. He has recovered fully.8. The lab analysed the blood sample.9. We found that the tissue was infected.10. We operated immediately.11. We replaced the patient's hip.12. His condition has degenerated.13.
His arm was paralysed after the stroke2. I made a full3. I wrote a4. He experienced very little5. Ten per cent of the population are thought to be6. There is no7. He has made a full8. The lab made an9. We found an10. The11. The patient was given a hip12. There has been a13. He sufferedExercise 6. Now make up your own sentences with the following verbs and corresponding nouns: to treat,to affect, to damage.Exercise 7. Using the information from the text in Exercise 3 speak on the following:1. History of hemispherectomy.2. Surgical indication.3.
Difference between functional and anatomical hemispherectomy.4. Positive and negative consequences of hemispherectomy.5. Implications of the operation for fundamental science.Exercise 8. Prove that the human body has unique adaptive abilities. Use the information from the text inExercise 3 and additional facts, if necessary. Combine all the information into one report.8Unit 2. WaterWater, thou hast no taste, no color, no odor; canst notbe defined, art relished while ever mysterious. Notnecessary to life, but rather life itself, thou fillest us witha gratification that exceeds the delight of the senses.Antoine de Saint-Exupery, The Wisdom of the SandsExercise 1. What do you know about water?1.
What are the functions of water in human organism? What processes is water involved in?2. What is the function of water in photosynthesis?3. Can water produce negative effect on the human body?4. What is dehydration? What negative consequences can it cause?5. Why does daily water consumption of different classes of animals – amphibians, reptiles, birds, mammals –differ?6. Do freshwater and saltwater kinds of fish have any difference in metabolism?7. Why can’t we use distilled water for drinking?Exercise 2.
How long can the average person survive without water?Now read the explanation given by Randall K. Packer, a professor of biology at George WashingtonUniversity, and check if your answer was correct.It is impossible to give an answer to this seemingly simple question because many variable factors determinea person's survival time. Under the most extreme conditions, death can come rather quickly. For example, a childleft in a hot car or an athlete exercising hard in hot weather can dehydrate, overheat and die in a period of a fewhours.
An adult in comfortable surroundings, in contrast, can survive for a week or more with no, or very limited,water intake.To stay healthy, humans must maintain water balance, which means that water losses must be made up forby water intake. We get water from food and drink and lose it as sweat and urine. Another major route of water lossusually goes unnoticed: because we exhale air that is water saturated, we lose water each time we exhale. On acold day we see this water in the air as it condenses.Exposure to a hot environment and vigorous exercise both increase body temperature. The onlyphysiological mechanism humans have to keep from overheating is sweating. Evaporation of sweat cools blood invessels in the skin, which helps to cool the entire body.
Under extreme conditions an adult can lose between oneand 1.5 liters of sweat an hour. If that lost water is not replaced, the total volume of body fluid can fall quickly and,most dangerously, blood volume may drop. If this happens, two potentially life-threatening problems arise: sweatingstops and body temperature can soar even higher, while blood pressure decreases because of the low bloodvolume.
Under such conditions, death occurs quickly. Because of their relatively larger skin surface-to-volume ratio,children are especially susceptible to rapid overheating and dehydration.The combination of dehydration and overheating sends thousands of people to hospital emergency roomseach year, but diarrhea, excessive vomiting, and kidney failures of various sorts can also cause dehydration.
Aperson can stay hydrated by drinking many different kinds of fluids in addition to water, with one exception. Drinkingalcoholic beverages actually causes dehydration because ethanol depresses the level of the anti-diuretic hormonearginine vasopressin (AVP). As a result, urine volume increases such that more fluid is lost in urine than is gainedby consuming the beverage.Exercise 3. Give definitions to the following terms connected with water:To dehydrate / to rehydrate, to condense, fluid, water balance, hormone, kidney, sweating, evaporation.Exercise 4.
According to the text in Exercise 2, what is more damaging for one’s health? Why?a. hot weatherb. high blood pressurec. sweatingd. drinking alcoholic beveragese. low blood pressuref. physical exerciseg. vomitingExercise 5. Now read the article about water overdose.Strange but True: Drinking Too Much Water Can KillIn a hydration-obsessed culture, people can and do drink themselves to death.By Coco Ballantyne9Liquid H2O is the sine qua non of life. Making up about 66 percent of the human body, water runs throughthe blood, inhabits the cells, and lurks in the spaces between.
At every moment water escapes the body throughsweat, urination, or exhaled breath, among other routes. Replacing these lost stores is essential but rehydrationcan be overdone. There is such a thing as a fatal water overdose.Earlier this year, a 28-year-old California woman died after competing in a radio station's on-air waterdrinking contest. After downing some six liters of water in three hours in the contest, Jennifer Strange vomited,went home with a splitting headache, and died from so-called water intoxication. There are many other tragicexamples of death by water.
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