6: Hypothalamus and Pituitary Hormones - Wilson

Question 1

neurosecretory cells with axons that terminate in the posterior lobe of the pituitary

Answer 1

magnocellular neurons

secrete large quantities of hormone into the systemic circulation

Question 2

neurosecretory cells with axons that terminate at the median eminence

Answer 2

parvicellular neurons

secrete small quantites of hromone into portal hypophysial system to regulate hormone release from anterior pituitary

Question 3

Gs –>
Gi –>
Gq –>

Answer 3

• increase cAMP and PKA
• decrease cAMP and PKA
• generate IP3 and diacyglycerol to increase Ca2+ and PKC

Question 4

where are oxytocin and argine vasopressing AVP synthesized?

Answer 4

they are peptide hormones synthesized in teh cell bodies of magnocellular neurons and then secreted into systemic circulation from posterior pit.

Question 5

functions of oxytocin (2)

Answer 5

1. smooth muscle contraction inducing labor

2. promotes milk ejection

Question 6

what gprtn does oxytocin use?

Answer 6

Gq

Question 7

oxytocin release is stimulated by (2) an inhibited by (1)

Answer 7

+ mechanical stimulation of uterine cervix by fetus
+ suckling of lactating breast
- sever pain, fever, and loud noises

Question 8

function of AVP (2)

Answer 8

1. water reabsorption in kidney

2. contraction of vascular smooth muscle

Question 9

what gptns does AVP activate?

Answer 9

• increases water permeability of collecting duct via Gs (aquaporin)
• raises blood pressure with Gq

Question 10

AVP release is stimulated by (2) and inhibited by (4)

Answer 10

\+ dehydration related changes in plasma osmolarity
\+ decreased blood pressure or volume
 - hydration
- increased blood pressure
- atrial natriuretic factors
- alcohol

Question 11

nephrogenic diabetes insipidus =

neurogenic diabetes inspidus =

Answer 11

defect in ability of kidney to respond to AVP

defect in AVP production

Question 12

CRH and GHRH use _______.
Somatostatin and Dopamine use ___.
TRH and GnRH use ____.

Answer 12

Gs
Gi
Gq

Question 13

ACTH and b-lipotropin

Answer 13

released in equimolar amounts when ACTH is derived from cleavage of pro-opiomelanocortin

B-lipotropin –> BMSH (melanocyte stimulating hormone)

Question 14

growth hormone mechanism

Answer 14

• single hormone molecule binds two receptor molecules
• activates JAK2
• JAK2 phosphorylates STAT5
• STAT5 enters the nucleus –> stimulation of prtn synthesis, transport of aa into cells, gluconeogenesis, lipolysis

Question 15

differences between insulin and IGF-I/II

Answer 15

c peptide is not removed from IGFI/II

a-chain contains an extension (d-chain)

Question 16

triggers somatic growth and cell proliferation

Answer 16

IGF-I

IGF-II mainly functions during fetal development

Question 17

what hormone inhibits GH?

Answer 17

somatostatin

IGF-I inhibits GH secretion (feedback) and stimulates secretion of somatostatin

Question 18

hypersecretion of GH –>

Answer 18

child = gigantism

adult = acromegaly

hyposecretion child = dwarfism

hyposecretion adult = fat, decreased strength and endurance

Question 19

promotion of milk synthesis and maintenance of milk secretion =

Answer 19

prolactin

Question 20

what hormone inhibits prolactin?

Answer 20

dopamine

Question 21

what are the lycoprtn hormones?

Answer 21

LH, FSH, and TSH

all two subunits with identical alpha subunits

all use Gs

Question 22

functions of LH

Answer 22

ovary: stimulates estrogen/progesterone secretion and gametogenesis
testes: stimulates testosterone production

Question 23

functions of FSH

Answer 23

ovary: stimulates estrogen/progesterone secretion and gamestogenesis
testes: functions in spermatogenesis