1. Why are organs such as the kidneys, stomach, heart, and skin considered part of the endocrine system?
2. Why are target cell receptors important?
3. Chemically, what types of molecules are hormones?
4. What are the general ways in which blood hormone levels are regulated?
5. In what respect is the pituitary gland actually two glands?
6. How do hypothalamic releasing and inhibiting hormones influence secretions of anterior pituitary hormones?
7. How is the secretion of T3 and T4 regulated? What are the actions of the thyroid hormones and calcitonin?
8. How is secretion of PTH regulated?
9. In what ways are the actions of PTH and calcitriol simi- lar? How do they differ?
10. What are the functions of insulin?
11. How are blood levels of glucagon and insulin controlled?
12. How do the adrenal cortex and adrenal medulla compare with regard to their location and histology?
13. How is secretion of adrenal cortex hormones regulated?
14. Why are the ovaries and testes included among the endocrine gland?
15. What is the relationship between melatonin secretion and sleep?
16. What hormones are secreted by the gastrointestinal tract, placenta, kidneys, skin, adipose tissue, and heart?
17. What are some functions of prostaglandins and leuko- trienes?
18. What is the role of the hypothalamus during stress? 20. How are stress and immunity related?
19. Which hormone is related to the muscle atrophy that occurs with aging?