Pituitary Gland

Question 1

Peptide hormones?

Answer 1

synthesised as PROHORMONES requiring further processing; Regulatory secretion (stored in vesicles); bind to cell membrane receptors (2nd messenger system)

Question 2

Steroid hormones?

Answer 2

synthesised from cholesterol; Constitutive secretion (released immediately); act on intracellular receptors

Question 3

What is the Anterior Pituitary?

Answer 3

Adenohypophysis, endocrine cells that produce various hormones

Question 4

How are AP hormones produced?

Answer 4

short parvocellular neurons in hypothalamus secrete Releasing/Inhibiting hormones in median eminence. Regulatory factors carried to AP via hypothalamo-pituitary portal circulation.

Question 5

AP cell types and hormones?

Answer 5

Somatotrophs -> Growth Hormone 
Lactotrophs -> Prolactin
Thyrotrophs -> TSH
Gonadotrophs -> LH/FSH
Corticotrophs -> Adrenocorticotrophic hormone ACTH

Question 6

GH regulatory factors?

Answer 6

+ GHReleasing Hormone, - Somatostatin

Question 7

Prolactin regulatory factors?

Answer 7

• Dopamine

Question 8

TSH regulatory factors?

Answer 8

+ TRH, - T4, - T3, - SS

Question 9

LH/FSH regulatory factors?

Answer 9

GnRH

Question 10

ACTH regulatory factors?

Answer 10

Corticotrophin RH, AVP

Question 11

Possible effect of pituitary tumour?

Answer 11

Bitemporal Hemianopia: reduced lateral field vision due to compression of optic chasm (where nasal retinae fibres cross)

Question 12

Excess GH in childhood?

Answer 12

Gigantism: excess production of GH results in abnormal growth (potentially caused by GH secreting AP tumour)

Question 13

Excess GH in adulthood?

Answer 13

Acromegaly: macroglossia (tongue biting, altered speech, dysphagia), increase in hand/foot size, sweatiness, headache, larger facial features

Question 14

What is Posterior Pituitary?

Answer 14

Neurohypophysis, nervous tissue continuous with hypothalamus, Oxytocin + AVP produced

Question 15

How are Oxytocin + AVP produced?

Answer 15

long magnocellular neuron fibres originate in hypothalamus and end in PP, neurosecretory cells secrete hormones when stimulated by excitation

Question 16

Where are magnocellular neurons?

Answer 16

Supraoptic nucleus (AVP), Paraventricular (oxytocin)

Question 17

AVP mechanism of action?

Answer 17

AVP stimulates reabsorption of water in collecting duct by binding to V2 receptors -> G protein coupled receptor transducer signal to move more aquaporin-2 into apical membrane

Question 18

oxytocin mechanism of action in breasts?

Answer 18

contractor hormone, stimulates breast myoepithelial cells to contract, ejecting milk

Question 19

oxytocin mechanism of action in uterus?

Answer 19

contractor hormone, stimulates myometrial cells to contract to push baby out of womb