THE V ERTEBRATE BODY 365 



11. How can the inguinal canal be a source of weakness in the human male? 



12. Why are men with undescended testes usually sterile ? 



13. How is progesterone used medically ? 



14. What is the function of estrogen? 



15. What are cretins and how may their condition be alleviated? 



16. What is the difference in the cause of gigantism and acromegaly? 



17. Describe the structure of the human kidney. 



18. What hormone maintains the proper calcium level in the blood? 



19. What three systems empty their products into the frog cloaca? 



20. Explain the changes brought about in the body by the injection of adrenalin. 



21. Distinguish between diabetes insipidus and diabetes mellitus as to cause and 

 symptoms. 



22. Why is the pituitary sometimes called the master gland of the body? 



