Open Library - открытая библиотека учебной информации

Открытая библиотека для школьников и студентов. Лекции, конспекты и учебные материалы по всем научным направлениям.


Химия Now read the explanation given by Randall K. Packer, a professor of biology at George Washington University, and check if your answer was correct.
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Unit 2. Water

Exercise 8. Prove that the human body has unique adaptive abilities. Use the information from the text in Exercise 3 and additional facts, if necessary. Combine all the information into one report.

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.

1. I diagnosedthat the patient had a heart condition.   2. I examinedthe patient fully. 3. I prescribeda course of antibiotics. 4. He sufferedvery little. 5. Ten per cent of the population are thought to carrythe bacteria. 6. This disease cannot be cured. 7. He has recoveredfully. 8. The lab analysedthe blood sample. 9. We found that the tissue was infected. 10. We operatedimmediately. 11. We replacedthe patient's hip. 12. His condition has degenerated. 13. His arm was paralysedafter the stroke   1. My diagnosis was that the patient had a heart condition. 2. I made a full 3. I wrote a 4. He experienced very little 5. Ten per cent of the population are thought to be   6. There is no 7. He has made a full 8. The lab made an 9. We found an 10. The 11. The patient was given a hip 12. There has been a 13. He suffered  

Exercise 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.

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 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?

It is impossible to give an answer to this seemingly simple question because many variable factors determine a person's survival time. Under the most extreme conditions, death can come rather quickly. For example, a child left in a hot car or an athlete exercising hard in hot weather can dehydrate, overheat and die in a period of a few hours. 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 for by water intake. We get water from food and drink and lose it as sweat and urine. Another major route of water loss usually goes unnoticed: because we exhale air that is water saturated, we lose water each time we exhale. On a cold day we see this water in the air as it condenses.

Exposure to a hot environment and vigorous exercise both increase body temperature. The only physiological mechanism humans have to keep from overheating is sweating. Evaporation of sweat cools blood in vessels in the skin, which helps to cool the entire body. Under extreme conditions an adult can lose between one and 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: sweating stops and body temperature can soar even higher, while blood pressure decreases because of the low blood volume. 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 rooms each year, but diarrhea, excessive vomiting, and kidney failures of various sorts can also cause dehydration. A person can stay hydrated by drinking many different kinds of fluids in addition to water, with one exception. Drinking alcoholic beverages actually causes dehydration because ethanol depresses the level of the anti-diuretic hormone arginine vasopressin (AVP). As a result, urine volume increases such that more fluid is lost in urine than is gained by 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 weather

b. high blood pressure

c. sweating

d. drinking alcoholic beverages

e. low blood pressure

f. physical exercise

g. vomiting