145b Hypothalamic - anterior pituitary physiology

Question 1

endocrine vs nervous system - timeframe of signals

Answer 1

endocrine is slow, but long lasting with slower adaptation

Question 2

posterior pituitary - aka? derived from? appearance on MRI?

Answer 2

neurohypophysis

neuroectoderm

bright on MRI

Question 3

anterior pituitary - aka? derived from? what is superior to it?

Answer 3

adenohypophysis (Adeno = Anterior)

nasopharynx ectoderm (Rathke’s pouch)

optic chiasm

Question 4

Does the hypothalamus secret hormones into portal veins for communication with the anterior or posterior pituitary?

Answer 4

anterior pituitary

Question 5

What causes the circadian rhythms secretion of hormones? what does this affect?

Answer 5

SCN

affect - testing hormone levels is difficult so must use suppression/stimulation tests AND continuous hormone levels actually depress downstream secretions

Question 6

what is the only pituitary hormones that is under tonic inhibition by a hypothalamus hormone?

which hypothalamus hormone does this?

Answer 6

Prolactin

Dopamine

Question 7

Prolactin - source

Answer 7

anterior pituitary

Question 8

prolactin - fxn

Answer 8

stimulates milk production

Inhibits GnRH synthesis and release thus inhibits ovulation/spermatogenesis

(remember that the body doesn’t want to ovulate while nursing so prevents another pregnancy too quickly)

Question 9

Prolactin regulation

Answer 9

+ TRH and VIP (minor role)
+ estrogen (pregnancy/OCP)
+ dopamine antagonists (antipsychotics)

• dopamine (major)
• dopamine agonists (Bromocriptine; rx for prolactinoma)

Question 10

growth hormone - source

Answer 10

anterior pituitary

Question 11

growth hormone - fxn

Answer 11

linear growth at epiphyseal plate/muscle mass via IGF-1 (mostly from liver but also bone)

osteoclast, osteoblast differentiation

differentiation of procondrocytes

increases insulin resistance (diabetogenic) b/c its a stress hormones (wants to increase blood glucose for use by CNS)

Question 12

Growth hormone - regulation

Answer 12

+ GHRH (pulsating) – increased during exercise and sleep

• somatostatin
• glucose

Question 13

growth hormone - source

Answer 13

anterior pituitary

Question 14

growth hormone - fxn

Answer 14

linear growth/muscle mass via IGF-1 (mostly from liver but also bone)

increases insulin resistance (diabetogenic) b/c its a stress hormones (wants to increase blood glucose for use by CNS)

Question 15

Growth hormone - regulation

Answer 15

+ GHRH (pulsating) – increased during exercise and sleep

• somatostatin
• glucose

Question 16

what does excess GH cause in adults? children?

Answer 16

acromegaly

gigantism

Question 17

IGFBP - what are they? purpose?

Answer 17

IGF binding proteins

carry IGF in plasma
increase half life of IGF

Question 18

what glycoprotein hormones share a structural subunit? which subunit?

Answer 18

TSH
FSH
LH
HCG

share alpha; beta give biological specifictiy
(“These Fucking Loser Hormones”)

Question 19

what causes growth plate closure during puberty?

Answer 19

estrogen mostly

Question 20

LH/FSH regulation

Answer 20

+ GnRH

-estrogen/progesterone, inhibin

Question 21

what glycoprotein hormones share a structural subunit? which subunit?

Answer 21

TSH
FSH
LH
HCG

share alpha; beta give biological specifictiy

Question 22

ACTH regulation

Answer 22

+ CRH, vasopressin

• cortisol (Feedback)

Question 23

LH/FSH regulation

Answer 23

+ GnRH

-estrogen/progesterone, inhibin

Question 24

What is ACTH synthesized from? what else is made?

Answer 24

POMC

makes MSH (tanning) too

Question 25

ACTH regulation

Answer 25

+ CRH, vasopressin

- cortisol (Feedback)

Question 26

AVP regulation

Answer 26

+ low volume (if it gets low enough)

+ high serum osmolarity (primary)

Question 27

What is ACTH synethized from?

Answer 27

POMC

makes MSH (tanning) too

Question 28

What is made by the neurohypophysis?

Answer 28

AVP

Oxytocin

Question 29

AVP regulation

Answer 29

+ low volume

+ high serum osmolarity

Question 30

AVP fxn

Answer 30

V 2 receptors –> aquaporin –> antidiuresis

V1 –> increased vWF –> smooth muscle contraction in intestine and skin (only at patholigcally high concentrations)

Question 31

oxytocin regulation

Answer 31

+ suckiling (via afferents to brain)

+ cervical stretch receptors

Question 32

oxytocin fxn

Answer 32

milk let down (myoeptihelial contraction)

uterian contractions