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Flashcards in Pituitary physiology III Deck (15):
1

When is prolactin secreted (time of day, life events)

incr. during preg and lactation
episodic secretion. begins after sleep and peaks 4-7 am. not a circadian rhythm, but a sleep-dependent one

2

What factors inhibit prolactin seccretion

dopamine
acts via D2 receptors in anterior pituitary.

3

describe regulation of prolactin secretion

TRH and VIP promote prolactin secretion from the anterior pituiary, as does sleep and hypothyroidism
decrease in estrogen and progesterone after delivery

4

What classes of drugs induce sustained hyperprolatcinemia

antipsychotics (haloperidol, risperidone, etc), antidepressants (tricyclics, MAO-I), buspirone, alprazolam, prokinetics (metoclopramide), antihypertensives (alpha-methyldopa, reserpine, verapamil), morphine, H2 antagonists (cimetindine, ranitidine)

5

What are some results of hyperprolactinemia

hypogonadism
women: shortened luteal phase, anovulation, oligomenorrhea, infertility
males: decr. testosterone synthesis and spermtogenesis

6

What is macroprolactin

high molecular weight complexes of prolactin and immunoglobulin
benign clinical condition

7

Where is TRH synthesized

supraoptic/supraventricular nuclei of the hypothalamus

8

When is TRH stimulated?

vasopressin and alpha adrenergic agonists stimulate TRH synthesis
also found in pancrease, GI, prostate, and testes

9

Kallman syndrome

no smell; GnRH deficiency prevents onset of puberty

10

What should I know about feedback regulation of thyroid function?

T4 and T3 have negative effects
dopamine decreases TSH
glucocorticoid excess impairs sensitivity of pituitary to TRH-- lowers TSH
estradiol incr. sensitivity to TRH- incr. serum TSH

11

What factors inhibit LH and FSH secretion

Testosterone, estrogen, progesterone
inhibin in in men

12

What hormones are important in PCOS

somewhat controversial, but we think that it is related to elevated LH levels. LH stimulation may cause excess ovarian androgen levels

13

Commonalities btw ADH and oxytocin

posterior pituitary hormones
both made as prehormones
borth released in response to an action potential

14

Diabetes insipidus

abosolute or relative deficiency of ADH leading to polyuria
may be primary if due to excess fluid intake
or may be central if there is abnormal decrease in the synthesis and secretion of ADH
may be nephrogenic if the kidneys stop responding to ADH

15

What does oxytocin do?

stimulates myoepthelial contractions in the uterus during parturition and in the mammary gland during lactation