Endo - Physiology (Hypothalamus & Pituitary)

Question 1

In hypothalamic-pituitary hormone regulation, what role does TRH play?

Answer 1

Hypothalamic TRH = Thyrotropin-releasing hormone stimulates TSH & prolactin release from anterior pituitary

Question 2

In hypothalamic-pituitary hormone regulation, what role does Dopamine play?

Answer 2

Hypothalamic Dopamine inhibits prolactin release from anterior pituitary

Question 3

In hypothalamic-pituitary hormone regulation, what role does CRH play?

Answer 3

Hypothalamic CRH = Corticotropin-releasing hormone stimulates ACTH and melanocyte-stimulating release from anterior pituitary as well as beta-endorphin release

Question 4

In hypothalamic-pituitary hormone regulation, what role does GHRH play?

Answer 4

Hypothalamic GHRH = Growth hormone-releasing hormone stimulates GH release from anterior pituitary

Question 5

In hypothalamic-pituitary hormone regulation, what role does Somatostatin play?

Answer 5

Hypothalamic Somatostatin inhibits release of GH & TSH from anterior pituitary

Question 6

In hypothalamic-pituitary hormone regulation, what role does GnRH play?

Answer 6

Hypothalamic GnRH = Gonadotropin-releasing hormone stimulates release of FSH & LH from anterior pituitary

Question 7

In hypothalamic-pituitary hormone regulation, what role does Prolactin play?

Answer 7

Prolactin release from the anterior pituitary inhibits GnRH release from the hypothalamus

Question 8

What is the source of Prolactin?

Answer 8

Secreted mainly by anterior pituitary

Question 9

What is the function of Prolactin?

Answer 9

(1) Stimulates milk production in breast (2) Inhibits ovulation in females and spermatogenesis in males by inhibiting GnRH synthesis and release

Question 10

What inhibits Prolactin, and what is the source of this factor? What is the feedback in place with regard to this process?

Answer 10

Dopamine from Hypothalamus; Prolactin in turn inhibits its own secretion by increasing dopamine synthesis and secretion from hypothalamus

Question 11

What stimulates Prolactin, and what is the source of this factor?

Answer 11

TRH from Hypothalamus

Question 12

What can be used in the treatment of prolactinoma, and why?

Answer 12

Dopamine agonists (e.g., bromocriptine) inhibit prolactin secretion

Question 13

What kinds of drugs stimulate prolactin secretion?

Answer 13

(1) Dopamine antagonists (most antipsychotics (2) Estrogens (OCPs, pregnancy)

Question 14

Draw the pathways of Prolactin that relate to the following: (1) Anterior Pituitary (2) Hypothalamus (3) Dopamine (4) TRH (5) Milk Production (6) GnRH (7) Spermatogenesis (8) Ovulation.

Answer 14

See First Aid p. 290

Question 15

What is another name for growth hormone? What is its source?

Answer 15

Somatotropin; Secreted mainly by anterior pituitary

Question 16

What is the major function of growth hormone (somatotropin)? What is an associated deleterious effect of GH?

Answer 16

Stimulates linear growth and muscle mass through IGF-1/somatomedin secretion; Increases insulin resistance (diabetogenic)

Question 17

What increases secretion of GH?

Answer 17

(1) Released in pulses in response to GHRH (2) Secretion increased during exercise and sleep

Question 18

What inhibits secretion of GH?

Answer 18

Secretion inhibited by glucose and somatostatin

Question 19

What is an example of a disease/condition that would cause excess secretion of GH? What can occur as a result of excess secretion of GH?

Answer 19

Pituitary adenoma; (1) Acromegaly (adults) (2) Gigantism (children)

Question 20

What is a clinical context in which CRH is decreased?

Answer 20

Decreased in chronic exogenous steroid use

Question 21

In what clinical context are dopamine antagonists used? What symptom can they cause, and why?

Answer 21

Dopamine antagonists (e.g. antipyschotics) can cause galactorrhea; Dopamine normally functions to decrease prolactin (i.e., increased prolactin due to dopamine antagonists causes galactorrhea)

Question 22

What regulates GnRH, and how so?

Answer 22

Regulated by prolactin; Prolactin decreases GnRH

Question 23

What is the outcome of tonic versus pulsatile GnRH?

Answer 23

Tonic GnRH suppresses HPA axis; Pulsatile GnRH leads to puberty, fertility

Question 24

What are 2 symptoms/results of pituitary prolactinoma?

Answer 24

Pituitary prolactinoma –> amenorrhea, osteoporosis

Question 25

What are somatostatin analogs used to treat, and why?

Answer 25

Analogs use to treat acromegaly; Somatostatin decreases GH

Question 26

Where exactly is antidiuretic hormone synthesized? Where is it released?

Answer 26

Synthesized in hypothalamus (supraoptic nuclei), released by posterior pituitary

Question 27

What are 2 major functions of antidiuretic hormone, and through which receptors does it accomplish these?

Answer 27

Regulates (1) serum osmolarity (V2-receptors) and (2) blood pressure (V1-receptors)

Question 28

Again, what are the 2 major functions of antidiuretic hormone, and through which receptors does it accomplish these? Which of these is its primary function, and what is the mechanism behind this?

Answer 28

Regulates (1) serum osmolarity (V2-receptors) and (2) blood pressure (V1-receptors); Primary function is serum osmolarity regulation (ADH decreases serum osmolarity, increases urine osmolarity) via regulation of aquaporin channel transcription in principal cells of renal collecting duct

Question 29

What are the primary versus secondary regulators of antidiuretic hormone?

Answer 29

Osmoreceptors in hypothalamus (primary); hypovolemia (secondary)

Question 30

What is the ADH level in each of the following clinical contexts: (1) Central diabetes insipidus (DI) (2) Nephrogenic DC (3) Primary polydipsia.

Answer 30

ADH level is (1-2) decreased in central diabetes insipidus (DI) and primary polydipsia (3) normal or increased in nephrogenic DI

Question 31

What mutation can cause nephrogenic DI?

Answer 31

Nephrogenic DI can be caused by mutation in V2 receptor

Question 32

What is desmopressin, and for what condition is it used as a treatment?

Answer 32

Desmopressin (ADH analog) = treatment for central DI