Anterior pituitary gland

Question 1

What hormones are secreted from the anterior pituitary gland?

Answer 1

Thyroid-stimulating hormone - TSH
Adrenocorticotropin hormone - ACTH
Growth hormone - GH
Prolactin - PRL
FSH
LH

Question 2

What cells are found in the pars distalis of the anterior pituitary gland?

Answer 2

Thyrotropes: TSH
Corticotropes: ACTH
Gonadotropes: FSH, LH
somatotropes: GH
LActotropes: PRL

Question 3

What cell is found in the pars intermedia of the anterior pituitary gland?

Answer 3

melanotropes: MSH

Question 4

Describe the cell types found in the anterior pituitary gland based on staining

Answer 4

Chromophils - stain well
Acidophils (eosin/red):
- somatotropes (GH)
- lactotropes (PRL)
Basophils (hematoxylin/blue):
- corticotropes (ACTH)
- thyrotropes (TSH)
- gonadotropes (FSH, LH)

Question 5

Fill in the table of the 5 cell types in the pars distalis

Answer 5

Question 6

What hormones regulate GH (somatotropin) secretion from the anterior pituitaty gland?

Answer 6

GH-releasing hormone (GHRH)
Somatostatin (GHIH)
Ghrelin

Question 7

what is the function of growth hormone?

Answer 7

Stimulates IGF-1 secretion from liver
Growth
Stimulates protein synthesis
Stimulates lipolysis
Inhibits glucose utilisation (inhibits insulin)

Question 8

How does lactotrope staining change?

Answer 8

Chromophil (acidophil) when storing PRL in cytoplasm
Chromophobe (poor staining) when PRL is released

Question 9

How are lactotropes/prolactin secretion regulated?

Answer 9

Tonic inhibition by dopamine
Stimulated by TRH
Hypertrophy during pregnancy in preparation for lactation

Question 10

What is the function of corticotropes?

Answer 10

Produce POMC prohormone (proopiomelanocortin)
Proteolytic hormones cleave POMC into other hormones e.g., ACTH and MSH
Prohormone convertase I => ACTH (distalis + intermedia)
Prohormone convertase II => MSH (intermedia)

Question 11

How is corticotrope function regulated?

Answer 11

Tonic stimulation by corticotropin-releasing hormone (CRH)
-ve feedback loop

Question 12

what is the function of thyrotopes?

Answer 12

Synthesis TSH
TSH acts on follicular cells of thyroid gland to produce thyroglobulin (becomes T3 and T4)

Question 13

How is thyrotrope function regulated?

Answer 13

Tonic stimulation by thyrotropin-releasing hormone (TRH) from hypothalamus

Question 14

What are closed and open feedback loops?

Answer 14

Closed - target cells secrete hormones that effect their own secretion
Open - no direct feedback, stopped by removal of stimulus or depletion of biochemicals

Question 15

Describe the feedback loop of ACTH secretion

Answer 15

Short -ve feedback loop
- ACTH from pit gland
- feedback to hypothalamus
- less CRH from hypothalamus

Question 16

Describe the feedback loop of cortisol

Answer 16

long -ve feedback loop
- cortisol from gland
- feedback to hypothalamus or pit gland

Question 17

Describe the feedback loop of oxytocin during parturition

Answer 17

Positive feedback:
- oxytocin causes uterine contraction
- uterine stretches => nervous impulses to hypothalamus
- more oxytocin released

Question 18

What systems are independent systems?

Answer 18

= do not rely on hypothalamus or pituitary gland
- glucose regulation
- calcium regulation
- Na and K regulation
- GI enzyme regulation

Question 19

What causes gigantism/giantism?

Answer 19

pituitary hyperactivity or neoplasia before adoloescence

Question 20

What causes acromegaly?

Answer 20

pituitary disorders after adolescence

Question 21

What is the effect of an adenoma of the pars distalis?

Answer 21

ACTH and GH secreting
nonfunctional

Question 22

What is the effects of a GH-secreting pars distalis tumour?

Answer 22

affects acidophils in pars distalis
excess GH (and IGF-1 from liver)
Alters growth and affects energy metabolism
Can cause diabetes mellitus

Question 23

Who has a small penis

Answer 23

Jorge

Question 24

who has a big penis

Answer 24

leah