endocrinology

Question 1

Primary hormone for stimulating both synthesis and secretion of GH from somatotrophs?

Answer 1

Growth hormone releasing hormone (GHRH)

Question 2

Primary physiologic effect of growth hormone?

Answer 2

stimulation of postnatal longitudinal growth

Question 3

which family of receptors do growth hormone cell surface receptors belong to?

Answer 3

Class 1 cytokine receptors

Question 4

primary physiologic role of prolactin

Answer 4

stimulation of milk production

Question 5

what is the major stimulus for ADH release?

Answer 5

Osmoreceptors in the hypothalamus and in the lamina terminalis detect osmolarity of ECF

Question 6

What is the vascular connection between hypothalamus and anterior pituitary?

Answer 6

hypophyseal portal system: concentrated neurohormones are secreted into capillary network and affect target organs. small amounts can have potent effect

Question 7

what is the neural connection between hypothalamus and posterior pituitary?

Answer 7

hypothalamic nuclei (supra optic and paracentricular) project axons into the posterior pituitary. location of magnocelluar neurons

Question 8

embryonic origin of posterior pituitary?

Answer 8

evagination of third ventricle so it is a neural extension

Question 9

embyronic origin of anterior pituitary?

Answer 9

Rathke pouch (evagination of the roof of the pharynx) so its endothelial tissue

Question 10

what 6 hormones are secreted by the anterior pituitary

Answer 10

Prolactin, TSH, GH, FHh, LH, ACTH (secretion is controlled by hypophysiotropic hormones)

Question 11

What hormones are stored and released by posterior pituitary?

Answer 11

ADH (vasopressin) - water balance

Oxytocin - milk and uterine contractions (also role in bonding)

Question 12

What is hypopituitarisum? (pituitary tumors)

Answer 12

compression of functional anterior pituitary tissue (often end up with more lactotrophs)

if posterior stalk is compressed -> diabetes insipidus

Question 13

what is bitemporal hemianopsia? (pituitary tumors)

Answer 13

As dura is elevated, the lateral optic nerves are crushed.

Question 14

what is the presentation of hyperprolactinemia due to a lactotroph adenoma?

Answer 14

amenorrhea, galactorrhea, loss of libido, and infertility.

Note: PRL inhibits GnRH secretion and directly impacts gonadal steriod production = infertility

Question 15

what is the most common functional disorder (result from hormone secreting tumours)

Answer 15

PRL - prolactinoma 50%

GH - giantism (children) acromegaly (adults)

Question 16

how could non-functional tumours lead to hypopituitarism? and what symptoms would result?

Answer 16

insufficient hormone production, affecting other hormones like
ACTH - adrenal insufficiency
TSH - hypothyroidism
FSH and LH - sexual dysfunction and infertility

Question 17

if a patient presents with
- reduced bone mineral density
- increased abdominal fat
- decreased stamina
- hyperlipidemia
- depression
what is a reasonable mechanism?

Answer 17

trauma to somatotrophs of anterior pituitary resulting in hypopituitarism

-> reduced GH is causing all these symptoms (and is first in the hormonal sequence)

Question 18

main differences in HPG axis in men and women in relation to feedback?

Answer 18

male - negative feedback from testosterone

female - negative or positive feedback

Question 19

during which sleep phase is GH secreted?

Answer 19

slow wave sleep

Question 20

what do magnocellular neurons secrete?

Answer 20

Vasopressin

Question 21

what is the primary cause of increased mortality in patients with untreated acromegaly?

Answer 21

Cardiovascular and cerebrovascular disorders

Question 22

which neuropeptide is a potent stimulus for the release of prolactin?

Answer 22

Thyrotropin-releasing hormone (TRH), oxytocin, vasoactive intestinal peptide

Question 23

ACTH up regulates the activity of the side cleavage enzyme, resulting in:

Answer 23

increased conversion of cholesterol to pregnenolone (SCC is the rate limiting step)