Pituitary Physiology Flashcards Preview

Endocrinology > Pituitary Physiology > Flashcards

Flashcards in Pituitary Physiology Deck (28):
1

What are the origins of the Anterior and posterior pituitary?

Anterior: Oropharynx ectoderm (Rathke's pouch)
Posterior: Neuroectoderm just below third ventricle

2

What are activating transcription factors in pituitary development? What happens with inactivating mutations

PROP-1: inactivation--> No FSH, LH, PRL, GH, TSH
Pit-1: responsible for somatotropes, lactotropes, thyrotropes

3

What is function of GH?

Stimulates IGF-1 secretion-->Anabolic function
Stimulates lipid/CHO metabolism

4

What is function of TSH?

Stimulates secretion of thyroid hormones-->regulates thyroid cell proliferation/survival

5

Function of ACTH?

Stimulates synthesis/secretion of corticotropins in adrenal cortex

6

Function of PRL?

milk production, inhibits GnRH (suppressing LH/FSH)

7

Function of LH?

Female: Induces ovulation and progesterone synthesis
Male: gametogenesis, leydig cells, synthesis/secretion of testosterone

8

Function of FSH?

Females: Stimulate estrogen synthesis, promote follicular growth
Males: promoters spermatogenesis

9

What are the rhythms in endocrinology? Describe them and give example

Circadian rhythms: daily pattern; most endocrine functions (i.e cortisol)

Ultradian rhythms: bursts of hormone secretion that can be superimposed on circadian rhythms (i.e gonadotropins)

10

Describe HPA Axis in relation to corticotropins

Hypothalamus secretes Corticotropin Releasing Hormone (CRH)
CRH stimulates ACTH produciton in Anterior pituitary
ACTH stimulates cortisol secretion in adrenal gland

11

What are extra-adrenal actions of ACTH? (2)

Stimulate lipolysis and increase skin pigmentation

12

What are stimuli for ACTH? (6)

CRH, stress, hypoglycemia, anxiety, depression, a/ß-adrenergic agonists

13

Explain pattern of ACTH Release: Circadian? Ultradian?

Diurnal pattern: peaks just before awakening
Also has pulsatility

14

Describe the HPA Axis for GH

Hypothalamus secretes GHRH (stimulatory) OR somatostatin (inhibitory factors)
Anterior pituitary secretes GH
Liver secretes IGF1, which provides negative feedback

15

GHRH: Function

Stimulatory factor for somatotropes

16

GHRH: What is stimulated by? (3) What inhibits it (2)

Stimulated by: hypoglycemia, dietary protein, exercise
Inhibited by: IGF-1, GH

17

What is function of Somatostatin?

Inhibits GH, TSH, PRL, glucagon, insulin

18

What are FDA analogs of Somatostatin? (2)

Octreotide and lantreotide

19

Describe HPA Axis for PRL

Hypothalamus secretes prolactin releasing factor (PRF) OR inhibitory dopamine
Anterior Pituitary secretes PRL (neg feedback hypothalamus)
Prolactin stimulates milk production

20

What are stimulating factors for PRL? (6)
What are inhibiting factors?

Stimulators: breast stimulation, stress, estrogen, sleep, dopamine antagonists, TRH

Inhibitors: DA, DA agonists

21

What is effect of prolactin on LH/FSH secretion?

It negatively regulates HPG axis-->Decreases secretion of LH/FSH

22

Describe HPG Axis

Hypothalamus releases GnRH (pulsatility/frequency important)
Pituitary secretes FSH/LH (pulsatile)
Ovary/Testis stimulated and weird things going on in terms of feedback (i.e low vs. high estrogen)

23

LH Function

Males: stimulate testosterone synthesis
Females: induces ovulation, stimulates progesterone synthesis

24

FSH Function

Male: facilitates sperm production
Female: Stimulates estrogen synthesis, promotes follicular growth

25

Describe Hypothalamic-Pituitary-Thyroid Axis

Hypothalamus stimulates TRH (stimulatory) or Somatostatin (inhibitory)
Ant Pituitary secretes TSH
Thyroid stimulation increases T4/T3 output (provides negative feedback via TRH receptors on pituitary)

26

In which axis is hypothalamic regulation primarily inhibitory?

Prolactin

27

Which are important inhibitory hypothalamic factors (2)

Somatostatin, Dopamine

28

In which axis is there positive feedback?

In HPG axis with ovulation