Essentials of Anatomy and Physiology

248 The Endocrine System

membrane, or within the cytoplasm or nucleus of

the target cell.

• The two-messenger mechanism: a protein hor-
  mone (1st messenger) bonds to a membrane
  receptor; stimulates formation of cyclic AMP
  (2nd messenger), which activates the cell’s
  enzymes to bring about the cell’s characteristic
  response to the hormone.
  
  
  • Steroid hormones diffuse easily through cell
    membranes and bond to cytoplasmic receptors.
    Steroid-protein complex enters the nucleus and
    activates certain genes, which initiate protein
    synthesis.
  
  
  
  

REVIEW QUESTIONS

1. Use the following to describe a negative feedback
   mechanism: TSH, TRH, decreased metabolic rate,
   thyroxine and T 3. (p. 232)


2. Name the two hormones stored in the posterior
   pituitary gland. Where are these hormones pro-
   duced? State the functions of each of these hor-
   mones. (pp. 227–228)


3. Name the two hormones of the anterior pituitary
   gland that affect the ovaries or testes, and state
   their functions. (p. 230)


4. Describe the antagonistic effects of PTH and calci-
   tonin on bones and on blood calcium level. State
   the other functions of PTH. (p. 233)


5. Describe the antagonistic effects of insulin and
   glucagon on the liver and on blood glucose level.
   (pp. 235–236)


6. Describe how cortisol affects the use of foods for
   energy. Explain the anti-inflammatory effects of
   cortisol. (pp. 240–241)


7. State the effect of aldosterone on the kidneys.
   Describe the results of this effect on the composi-
   tion of the blood. (p. 240)


8. When are epinephrine and norepinephrine
   secreted? Describe the effects of these hormones.
   (p. 237)
   9. Name the hormones necessary for development
   of egg cells in the ovaries. Name the hormones
   necessary for development of sperm in the testes.
   (p. 243)


9. State what prostaglandins are made from. State
   three functions of prostaglandins. (p. 244)


10. Name the hormones that promote the growth of
    the endometrium of the uterus in preparation for
    a fertilized egg, and state precisely where each
    hormone is produced. (p. 243)


11. State the functions of thyroxine and T 3. For what
    aspects of growth are these hormones necessary?
    (pp. 231–232)


12. Explain the functions of GH as they are related to
    normal growth. (pp. 228–229)


13. State the direct stimulus for secretion of each of
    these hormones: (pp. 227, 229, 232, 233, 235, 240,
    241, 243)
    a. Thyroxine
    b. Insulin
    c. Cortisol
    d. PTH
    e. Aldosterone

f. Calcitonin

g. GH

h. Glucagon

i. Progesterone

j. ADH

FOR FURTHER THOUGHT

1. During a soccer game, 12-year-old Alicia got in a
   tangle with another player, fell hard on her hand,
   and fractured her radius. She is going to be fine,
   though she will be wearing a cast for a few weeks.

What hormones were secreted immediately after

the injury? What functions do they have? What

hormones will contribute to the healing of the

fracture, and how?