hypothalamic-pituitary relationships

Question 1

the connections between the hypothalaus and posterior lobe are what

Answer 1

neural

Question 2

the connections between the hypothalamus and anterior lobe are what

Answer 2

both neural and endocrine

Question 3

what kind of cells release growth hormone

Answer 3

somatorophs

Question 4

what part of the adrenal gland does ACTH stimulate

Answer 4

cortex and medulla

Question 5

the TRH receptor is what kind of second messenger

Answer 5

Gq–> PLC and calcium and PKC

Question 6

the TSH receptor is what kind of second messenger

Answer 6

Gs, adenylate cyclase, PKA

Question 7

what inhibits GnRH neurons

Answer 7

opoids, prolactin, stress

Question 8

regulation of GH secretion what + stimulates hypothalamus

Answer 8

GH and somatomedins (IGF)

Question 9

regulation of GH secretion what inhibits AP

Answer 9

somatodmedins (IGF) and Somatostatin

Question 10

actions of GH: diabetogenic effect

Answer 10

• causes insulin resistance
• decreases glucose uptake and utilization by target tissues
• incresases lipolysis in adipose tissue
• results in increased blood insulin levels**

Question 11

other actions of GH

Answer 11

1) increased protein synthesis and organ growh
- increase uptake aa,
2) increases linear growth
- increases metabolism in cartilage forming cells and chondrocyte proliferation

• both stimulate DNA,RNA, and protein synthesis
• both mediated by somatomedins

Question 12

what is a somatostatin analogue that inhibits GH

Answer 12

octreotide

Question 13

prolactin negatively or positvely stimulates hypothalamus

Answer 13

positvely stimulates to increase more prolactin release

Question 14

what inhibits prolactin and what are 3 main sources

Answer 14

dopamine

1) hypothalamus secretes dopamine to median eminence
2) dopamine neurons release dopamine from posterior pituit –>AP through portal veins
3) lactotrophs can release dopamine, (paracrine mech)

Question 15

why doesn’t lactation occur during pregnancy?

Answer 15

even though prolactin levels are high, progesterone and estrogen down regulate prolactin receptors
-at birth inhibition released when estrogen and progesterone levels drop

Question 16

prolactin deficiency results in inability to __ and caused by what

Answer 16

lactate

-caused by destruction of AP or desruction of lactotrophs

Question 17

prolactin excess can lead to what

Answer 17

galactorrhea and infertility

Question 18

prolactin excess caused by

Answer 18

destruction of hypothalamus resulting in loss of dopamine inhibtion
-prolactinomas (prolactin secreting tumor)

Question 19

what is a receptor agonist that can be used to treat prolactin excess

Answer 19

bromocriptine

Question 20

what is a craniopharyngioma

Answer 20

most common tumor affecting the HP axis in children

-causes hypopituitarism

Question 21

sheehan syndrome

Answer 21

pituitary in pregnancy is enlarged and more vulnerable to infarction. AP gland cells are hypertrophic and become necrotice

Question 22

most pituitary adenomas are benign or malignant?

Answer 22

benign and slow growing

Question 23

precursor peptide of ADH

Answer 23

preprossophysin

Question 24

precursor peptide of oxytocin

Answer 24

prepro-oxyphysin

Question 25

precursor of ADH has another fragment ____ so when precursor is cleaved there ADH is stored with this in the vesicle in the posterior pituitary

Answer 25

Neruophysin II

Question 26

what are the triggers of ADH secretion

Answer 26

1) increased osmolarity -->hypothalamic osmoreceptors -->interneurons to hypothalamus 2) decreased BP-->cardiac and aortic baroreceptors-->sensory neuron to hypothal 3) decreased arterial stretch due to low blood volume-->atrial stretch receptors-->sensory neuron to hyothalamus 4) increased angiotensin II 5) sympathetic stimulation 6) dehydration

Question 27

what receptor does ADH bind on blood vessels and causes what

Answer 27

V1 causes vasoconstriction

Question 28

what receptor does ADH bind on kindey and causes what

Answer 28

V2 and causes increased water reabsorption

Question 29

what is the mechanism of ADH in renal collecting duct

Answer 29

ADH binds V2 recetpors coupled to Gs proteins - leads to aquaporin 2 on apical side, water into cell - aquaporin 3 on BL side sends water from cell to blood

Question 30

oxytocin is stored in the PP with what after cleavage

Answer 30

NP1