Hypothalamic-Pituitary Axis

Question 1

Stress is a regulator of the HPA axis. Is it inhibitory or stimulatory

Answer 1

Stimulatory

Question 2

TRH are released from which neurons?

Answer 2

Parvicellular hypothalamic neurons.

Question 3

Is stress (infection, starvation) stimulatory or inhibitory to the HPT axis?

Answer 3

Inhibitory.

Question 4

What second messneger does TRH receptor use?

Answer 4

Ca and PKC (Gq)

Question 5

What second messenger does TSH receptor?

Answer 5

PKA (Gs)

Question 6

What second messenger does GnRH receptor use?

Answer 6

Ca, PKC and other (Gq)

Question 7

What second messenger does LH and FSH receptor use?

Answer 7

PKA, (Gs)

Question 8

Inhibin is produced by what cells and where does it act to inhibit FSH secretion?

Answer 8

Produced in sertoli cell to inhibit FSH release from anterior pituitary.

Question 9

Pulsatile secretion of GH occurs every _

Answer 9

2 hrs

Question 10

During what period of life are GH release the greatest?

Answer 10

puberty

Question 11

What are the actions of GH?

Answer 11

1. Diabetogenic effect (increase blood glucose)
2. Increase protein synthesis and organ growth
3. increase linear growth

Question 12

In diabetogenic effect of GH, glucose uptake is _ (increase or decrease), lipolysis in adipose tissue is _(increase or decreased).

Answer 12

decrease glucose uptake

Increase lipolysis

Question 13

In the protein synthesis and organ growth actions of GH, what mediates the uptake of amino acid for protein synthesis and organ growth?

Answer 13

Mediated by somatomedins

Question 14

Octreotide is used to treat what disease?

Answer 14

Octrotide is a somatostatin analogue which is used to inhibit GH secretion in GH secretion excess.

Question 15

what are the stimulatory and inhibitory actions of prolactin?

Answer 15

Stimulated by TRH. Inhibited by dopamine. Positively feedback to hypothalamus to release more TRH.

Question 16

At puberty, prolactin supports the action of what other hormones to develop the breasts?

Answer 16

progesterone and estrogen. Prolactin, along with progesterone and estrogen stimulate proliferation and branching of mammary ducts.

Question 17

During pregnancy, prolactin combined with actions of progesterone and estrogen stimulates breast development by stimulating the growth and development of _ ?

Answer 17

mammary alveoli

Question 18

During pregnancy, even with high levels of prolactin, lactation doesnt occur why?

Answer 18

High levels of estrogen and progesterone down-regulate prolactin receptors.

Question 19

Prolactin inhibits synthesis and secretion of what hormone to suppress ovulation

Answer 19

GnRh

Question 20

Prolactin excess can cause iinfertility how?

Answer 20

prolactin is a feedback inhibitor of GnRH

Question 21

Bromocriptine which is a _ receptor agonist, can be used to treat _

Answer 21

DA receptor agonist. Used to treat prolactin excess.

Question 22

What are some causes of hypopituitarism

Answer 22

1. Brain damage
2. Pituitary tumors
3. non-pituitary tumors like craniopharyngioma
4. infections
5. Autoimmne disorders
6. Pituitary hypoplasia or aplasia
7. genetic causes
8. Idiopathic causes.

Question 23

Sheehan syndrome is a cause of hypopituitarism caused by _.

Answer 23

enlarged of pituitary in pregnancy making it more vulnerable to infarction.

Question 24

Prolactinoma is associated with _ and _

Answer 24

hypoganodism and galactorrhea.

Question 25

What type of tumors are common in patients with MEN 1 (25%)?

Answer 25

Pituitary adenomas.

Question 26

Osmolarity is sensed by what receptors and where does the signal go from there.

Answer 26

Sensed by hypothalamic osmoreceptors and signal is relayed to interneuron to thehypothalamus and then to hypothalamic neurons tha syntehsize ADH. ADH then goes to posterior pituitary.

Question 27

What are the triggers for secrtion of ADH?

Answer 27

1. increased plasma osmolarity 2. decreased blood pressure 3. decreased blood volume 4. increased ang II 5. sympathetic stimulation 6. dehydration

Question 28

Secretion of ADH is most senstive to changes in _ such that an increase in only _% will increase ADH secretion.

Answer 28

Osmolarity. | 1%

Question 29

ADH works via what receptor in the kidney?

Answer 29

V2 receptors.

Question 30

ADH works via what receptor in the blood vessel to vasoconstrict?

Answer 30

V1 receptors

Question 31

V2 receptors are located where specifically? (cell type and border)

Answer 31

Principle cell lining the late distal tubular or collecting duct of the kidney. Located on the vasolateral border.

Question 32

What second messenger does ADH signaling use?

Answer 32

cAMP (Gs)

Question 33

What type of aquporin are placed on the tubular fluid side done by actions of ADH?

Answer 33

Aquaporin-2. | Aquaporin 3 is on the basolateral side.

Question 34

True or false. ADH secretin is more sensitive to volume contraction than to osmolarity.

Answer 34

Osmolarity

Question 35

What is diapetes insipidus?

Answer 35

Lack of an effect of ADH on the renal collecting duct. Causes frequent urination and large volume of urine is diluated.

Question 36

Desmopressin can be used to treat what?

Answer 36

Central DI.

Question 37

What drug can be used to treat SIADH and what receptor does it work on?

Answer 37

Demeclocycline, V2 receptor antagonist