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1. What are the differences in composition between the glomerular fluid and the urine that finally leaves the kidneys.

2. Alcohol dilates the arteries in the skin. What would be its effect, then, on the temperature control of the body?

3. Synthesis of urea occurs in what organ?

4. List the most important structures for maintaining water balance in the (a) amoeba (b) trout  (c) human (d) Elodea.

5. Carnivorous mammals excrete a higher concentration of urea than herbivorous ones. Explain.

6. What is the chief nitrogenous waste of the (a) rattlesnake (b) dog (c) chicken (d) shark.

7. Trace the path traversed by a molecule of urea from entering the renal artery to leaving the body.

8. How does the quantity of urine formed by a frog change when it moves from a pond onto land? Would the quantity of urine formed by a beaver change under the same circumstances?

9. During the formation of urine, why does the concentration of salts not increase in proportion to the concentration of urea?

10. In the mammalian kidney, water is reabsorbed from the filtrate across the wall of the collecting duct into the salty tissue near the bottom of the loops of Henle; blood vessels then take the water away. Why doesn’t the blood in these vessels become very salty?

11. If you are lost in the desert with a case of liquor and are desperately thirsty, should you drink the liquor? Explain you answer.

12. In the Malpighian corpuscles, fluid is forced out of the capillaries by blood pressure. Why does this not happen in the gills of freshwater fish?

13. Which gland has a hormone that may influence intelligence?

14. How do you account for the fact that the heartbeat of a basketball player increases a great deal before the game as well as during the game?

15. Why is a study of the endocrine glands often carried on at the same time as a study of the nervous system?

16. What hormone injected into the bloodstream of a male rat will often result in a mothering instinct?

17. Discuss dynamic balance in the endocrine system that results from feedback?

18. Summarize the mechanisms, which participate in the control of the blood-sugar level in the body.

19. How will each of the following affect the quantity and composition of urine formed in humans: (a) hypersecretion of ADH (b) hyposecretion of insulin (c) drinking copious amounts of water.

20. Which endocrine glands are controlled by the secretion of other endocrine glands?

21. Compare the mechanisms by which (a) the body regulates the concentration of water in the blood and (b) a steady temperature is maintained in your home.

22. Distinguish between the molecular activities that take place when each of the following interacts with one of its target cells: (a) a polypeptide or protein hormone and (b) a steroid hormone.

23. Why do you suppose the brain goes to the trouble of synthesizing and releasing hormones, rather than simply directing the production of the pituitary hormones immediately?

24. Why do you suppose steroid hormones do not employ second messengers when so many peptide hormones do?