41-HYPOTHALAMUS AND PITUITARY – Dr. Block Flashcards Preview

Medical Biochemistry - 3 > 41-HYPOTHALAMUS AND PITUITARY – Dr. Block > Flashcards

Flashcards in 41-HYPOTHALAMUS AND PITUITARY – Dr. Block Deck (18):
1

Where is vasopressin synthesized, secretd, and what is it's function?

Vasopressin:
Synthesize: hypothalamus
Secreted in posterior pituitary
Function: Inhibits water diuresis (increases Arterial BP).

2

Briefly compare the structures of vasopressin and oxytocin.

Both are nonapeptides with intramolecular disulfide bonds and their primary structure differs only by 2 AA

3

What is the situation with respect to growth hormone and its receptors in Laron dwarfs, G.H. deficient dwarfs, pygmies, acromegaly and gigantism?

G.H. deficient dwarfs: normal receptors but low G.H.

Laron dwarfs : excessive G.H., but lack hepatic receptors = low levels of IGF

Pygmies: normal G.H. levels, but a G.H. receptor defect = low levels of IGF

Acromegaly = excess G.H. after epiphyseal closure. Normal receptor.

Gigantism = excess G.H. before epiphyseal closure. Normal receptor.

4

Name 3 glycoprotein hormones synthesized and secreted at the anterior pituitary and give their functions.

TSH – increases volume and vascularity of thyroid gland and I concentrations. Stimulates Thyroid hormones and promotes lipolysis in adipose

FSH – stimulates growth/development of ovarian follicle and spermatogenesis.

LH – maturation of ovarian follicle to eventually corpus luteum and androgen production by Leydig cells.

5

What is the POMC family of hormones? Give 3 members, their function, where they are synthesized and secreted.

Pro-opiomelanocortin (POMC) hormones act as hormones, neuromodulators and neurotransmitters.

Synthesized in the gut/reproductive tract and secreted from the anterior pituitary.

1) ACTH: regulates growth and function of adrenal cortex.
2) Beta-LPH: causes lipolysis and fatty acid mobilization
3) MSH (melanocyte stimulating hormone): causes dispersion of intracellular melanin granules resulting in skin darkening

6

What is Cushings syndrome?

Excessive production of ACTH by pituitary gland or a tumor. Symptoms: hyperpigmentation (by increased MSH), Na+ retention (HTN), glucose intolerance (diabetes), muscle atrophy, and peculiar redistribution of fat

7

What are endorphins? Where are they synthesized and secreted?

Endorphins are a group of compounds that bind to the same CNS receptor as morphine and play a role in pain perception. Synthesized and secreted from anterior pituitary.

8

Give 4 releasing hormones and 2 inhibitory factors secreted by the hypothalamus and list their functions.

Releasing hormones: (end in RH)
- TRH (thyrotropin releasing hormone) – stimulates release of thyrotropin and prolactin.
- GnRH (gonadotropin R.H.) – stimulates release of LH and FSH.
- CRH (corticotropin R.H.) - stimulates release of ACTH and beta-endorphin.
- GHRH (growth hormone R.H.) – stimulates release of GH.

Inhibitory:
GHR inhibitory factor (somatostatin) – inhibits G.H., insulin, glucagons and gastrin release.
PRL inhibitor – inhibits prolactin release (Ex. high dopamine concentrations)

9

Where is Oxytocin synthesized, secreted, and what is it's function?

Synthesized in hypothalamus
Secreted in posterior pituitary
Function: stimulates uterine contractions and lactation.

10

Where is growth hormone synthesized, secreted, and what is it's function? How big is it?

Synthesized/secreted in anterior pituitary

Function: affects metabolic processes in all body parts (increase growth, increase protein synthesis, increase gluconeogenesis)

191 AA long!

11

Where is prolactin synthesized, secreted, and what is it's function?

Synthesized/secreted in anterior pituitary

Function: stimulates lactation in mammary tissue and stimulates protein synthesis [direct effect on tissues]

12

What drugs or agents are potent in stimulating the release or suppressing vasopressin?

Caused by pain, stress, hemorrhage, anoxia, or transfusion.

Stimulators: Acetylcholine and Histamine
Suppressers: NE

13

What is primary diabetes insipidus?

the hypothalmaic-hypohyseal tract is destroyed by infection, trauma or tumors

14

What is hereditary diabetes insipidus?

a disorder where vasopressin secretion is normal, but target cell receptors are deficient

15

What is acquired diabetes insipidus?

caused by treatment with lithium, which results in inappropriate ADH secretion by lung tumors.

16

What substances mediate growth hormone?

Other hormones like Somatomedin and Insulin-like growth factor (IGF-1)

17

A female patient walks in complaining about a lack of menses and frequent breast discharge, what might be occurring?

A tumor of prolactin producing cells producing excessive prolactin

18

A male patient walks in complaining about impotence and growth in his breasts, what is likely occuring?

tumors of prolactin producing cells causing excessive prolactin