Pituitary physiology and pathophysiology II

Question 1

what are the four tropic hormones released by the anterior pituitary? what does tropic mean?

Answer 1

ACTH
TSH
FSH
LH

these have effects on morphology and secretory activity of other endocrine glands

Question 2

which hormone has both tropic and non-tropic effects?

Answer 2

GH

Question 3

where are adrenocorticotropic hormones made?

Answer 3

corticotroph cells of the anterior pituitary

Question 4

what is the function of ACTH?

Answer 4

stimulates synthesis and secretion of the adrenocortical hormones by the adrenal cortex - stimulation of cortisol synthesis and secretion

Question 5

do androgens have negative feedback activity on ACTH secretion?

Answer 5

no

Question 6

what causes the release of adrenocorticotropin from the anterior pituitary?

Answer 6

CRH

Question 7

how are corticotropes made?

Answer 7

1. large precursor protein - preproopiomelanocortin
2. proopiomelanocortin (POMC)
3. POMC hydrolyzed to ACTH and beta-lipotropin (LPH) and beta endorphin

all three substances are secreted from the corticotrophs

Question 8

where is TSH produced?

Answer 8

thyrotrophs of anterior pituitary

Question 9

what stimulates the release of prolactin?

Answer 9

TRH

Question 10

function: FSH (males and females)

Answer 10

males - sperm maturation

females - growth of follicles in ovareis

Question 11

function: LH (males and females)

Answer 11

males - stimulation of testosterone synthesis in testes

females - stimulation of ovulation, formation of corpus luteum, estrogen / progesterone synthesis in ovaries

Question 12

GH release is regulated by what two opposing hypothalamic hormones?

Answer 12

hypothalamic growth hormone releasing hormone

somatostatin - inhibitory

Question 13

how does enlargement of the anterior pituitary during pregnancy make the pituitary more likely to suffer ischemia?

Answer 13

if patient becomes hypotensive due to postpartum hemorrhage (Sheehan syndrome)

Question 14

what is Sheehan syndrome?

Answer 14

aka postpartum hypopituitarism - necrosis of pituitary due to ischemia

Question 15

prolactin release is predominantly under tonic inhibition by what hormone?

Answer 15

prolactin inhibiting hormone - dopamine

Question 16

why does a tumor compressing the pituitary stalk cause hyperprolactinemia?

Answer 16

dopamine cannot reach anterior pituitary - prolactin release increases

Question 17

where and how are ADH and oxytocin released?

Answer 17

synthesized as pre-prohormones in magnocellular neurons located in the supraoptic and paraventricular nuclei of the hypothalamus

Question 18

pathophysiology: neurogenic / central diabetes insipidus

Answer 18

lack of ADH production in the brain
result - increased urine production and volume depletion

little or no ADH reaches kidneys due to trauma, infection or cancer - collecting ducts cannot produce concentrated urine

Question 19

pathophysiology: nephrogenic diabetes insipidus

Answer 19

mutation that affects vasopressin receptors for ADH on collecting ducts in the kidney, or the insertion of aquaporins needed to produce concentrated urine

Question 20

what are the cells responsible for causing milk ejection?

Answer 20

myoepithelial cells lining the breast ducts