Design a study to test the hypothesis that the symptoms of jet lag are caused by disruption of normal daily cortisol rhythms.

If a person has a pituitary tumor that is oversecreting TSH, would this person be likely to have goiter as a symptom? Explain.

Compare and contrast the structure and function of the anterior and posterior pituitary glands.

DRAW IT In mammals, milk production by mammary glands is controlled by prolactin and prolactin-releasing hormone. Draw a simple sketch of this pathway, including glands, tissues, hormones, routes for hormone movement, and effects.

Which two of the hormones listed below act upon the body with similar functions? Explain. a. glucagon b. oxytocin c. glucocorticoids d. ADH

A strain of mice remains healthy as long as they are fed regularly. After they eat, their blood glucose level rises slightly and then declines to a homeostatic level. However, when these mice fast or exercise, their blood glucose drops dangerously. Which hypothesis best explains their problem? (Explain your choice.) a. The mice have insulin-dependent diabetes. b. The mice lack insulin receptors on their cells. c. The mice lack glucagon receptors on their cells. d. The mice cannot synthesize glycogen from glucose.

Suppose that during a detailed anatomical study of a marine invertebrate, you found a small, previously undescribed structure. How would you test the hypothesis that the structure is a gland that releases one or more hormones?

SCIENTIFIC THINKING The results of Tyrone Hayes's experiments (Module 26.3) were published in a top peer-reviewed journal, yet the validity of his experiments has since been challenged. Using external sources, find out who has challenged the results.

Scientists set out to test the hypothesis that the herbicide atrazine is an endocrine disruptor that feminizes male amphibians. They treated male amphibians with atrazine and then compared their circulating testosterone concentration with those of males and females that were not treated with atrazine (controls). The results are shown here (* signifies P<0.05). Was the hypothesis supported? Why or why not?