Hypothalamic-Pituitary Axis Flashcards

1
Q

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

A

Stimulatory

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2
Q

TRH are released from which neurons?

A

Parvicellular hypothalamic neurons.

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3
Q

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

A

Inhibitory.

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4
Q

What second messneger does TRH receptor use?

A

Ca and PKC (Gq)

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5
Q

What second messenger does TSH receptor?

A

PKA (Gs)

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6
Q

What second messenger does GnRH receptor use?

A

Ca, PKC and other (Gq)

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7
Q

What second messenger does LH and FSH receptor use?

A

PKA, (Gs)

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8
Q

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

A

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

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9
Q

Pulsatile secretion of GH occurs every _

A

2 hrs

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10
Q

During what period of life are GH release the greatest?

A

puberty

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11
Q

What are the actions of GH?

A
  1. Diabetogenic effect (increase blood glucose)
  2. Increase protein synthesis and organ growth
  3. increase linear growth
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12
Q

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

A

decrease glucose uptake

Increase lipolysis

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13
Q

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

A

Mediated by somatomedins

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14
Q

Octreotide is used to treat what disease?

A

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

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15
Q

what are the stimulatory and inhibitory actions of prolactin?

A

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

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16
Q

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

A

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

17
Q

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

A

mammary alveoli

18
Q

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

A

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

19
Q

Prolactin inhibits synthesis and secretion of what hormone to suppress ovulation

A

GnRh

20
Q

Prolactin excess can cause iinfertility how?

A

prolactin is a feedback inhibitor of GnRH

21
Q

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

A

DA receptor agonist. Used to treat prolactin excess.

22
Q

What are some causes of hypopituitarism

A
  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.
23
Q

Sheehan syndrome is a cause of hypopituitarism caused by _.

A

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

24
Q

Prolactinoma is associated with _ and _

A

hypoganodism and galactorrhea.

25
Q

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

A

Pituitary adenomas.

26
Q

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

A

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.

27
Q

What are the triggers for secrtion of ADH?

A
  1. increased plasma osmolarity
  2. decreased blood pressure
  3. decreased blood volume
  4. increased ang II
  5. sympathetic stimulation
  6. dehydration
28
Q

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

A

Osmolarity.

1%

29
Q

ADH works via what receptor in the kidney?

A

V2 receptors.

30
Q

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

A

V1 receptors

31
Q

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

A

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

32
Q

What second messenger does ADH signaling use?

A

cAMP (Gs)

33
Q

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

A

Aquaporin-2.

Aquaporin 3 is on the basolateral side.

34
Q

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

A

Osmolarity

35
Q

What is diapetes insipidus?

A

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

36
Q

Desmopressin can be used to treat what?

A

Central DI.

37
Q

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

A

Demeclocycline, V2 receptor antagonist