Hypothalamus and Pituitary Gland

Question 1

Where is the pituitary gland located? [3]

Answer 1

in the pituitary fossa (sella turcica) / below the hypothalamus / and optic chiasm

Question 2

What is the pituitary gland composed of? [4]

Answer 2

1. anterior pituitary (adenohypophis) - develops from ectoderm in the mouth (Rathke’s pouch)
2. posterior pituitary (neurohypophis) - develops from neural components of the hypothalamus

Question 3

How do hypophysiotropic hormones act on the pituitary gland? [3]

Answer 3

hypothalamus releases the hormones into the blood stream / carried to the anterior pituitary via hypothalamo-hypophyseal portal vessels/veins / bind to G-protein coupled receptors

Question 4

What are the 6 hypophysiotropic hormones and what do they stimulate/inhibit? [12]

Answer 4

1. CRH - stimulates ACTH
2. GHRH - stimulates GH
3. TRH - stimulates TSH
4. somatostatin - inhibits GH and TSH
5. GnRH - stimulates FSH and LH
6. dopamine - inhibits prolactin

Question 5

What are the 6 anterior pituitary hormones and what cells produce them? [12]

Answer 5

1. FSH - gonadotrophs
2. LH - gonadotrophs
3. ACTH - corticotrophs
4. TSH - thyrotrophs
5. Prolactin - lactotrophs
6. GH - somatotrophs

Question 6

What does FSH do? [3]

Answer 6

stimulates germ cell development / oestrogen release / and LH

Question 7

What does LH do? [3]

Answer 7

stimulates release of the egg / and progesterone release / in men stimulates testosterone release

Question 8

What does ACTH do? [3]

Answer 8

stimulates adrenal cortex to increase cortisol production / and androgen production / stimulates adrenal medulla to increase adrenaline release

Question 9

What does TSH do? [1]

Answer 9

stimulates thyroid to increase release of T3 and T4

Question 10

What does prolactin do? [2]

Answer 10

stimulates breasts to produce milk / and help with breast development

Question 11

What does GH do? [3]

Answer 11

stimulates growth and protein synthesis / stimulates gluconeogenesis and inhibits insulin / acts on liver to stimulate IGF-1 production

Question 12

What is long loop negative feedback? [3]

Answer 12

hormone secreted by third endocrine gland / exerts negative feedback on anterior pituitary / and hypothalamus

Question 13

What is short loop negative feedback? [2]

Answer 13

anterior pituitary hormone / exerts negative feedback on the hypothalamus

Question 14

What hormones does the posterior pituitary store and release, and where are they produced? [4]

Answer 14

1. Vasopressin/ADH - supraoptic nucleus of hypothalamus

2. Oxytocin - paraventricular nucleus of hypothalamus

Question 15

What are the functions of vasopressin? [3]

Answer 15

1. increase water reabsorption from DCT and collecting ducts to retain fluid
2. vasoconstriction to increase blood pressure
3. stimulate ACTH release and aldosterone release to further increase fluid retention

Question 16

What are the functions of oxytocin? [3]

Answer 16

1. stimulates the release of milk during breast feeding
2. stimulates the contraction of uterine smooth muscles
3. promotes the onset of labour

Question 17

What are the three vital presentation points of a pituitary tumour? [3]

Answer 17

1. pressure on local structures
2. pressure on normal pituitary - hypopituitarism
3. functioning tumour - hyperpituitarism

Question 18

What can be the effect of pressure on local structures near the pituitary? [2]

Answer 18

pressing on the optic chiasm / can lead to bitemporal hemianopia

Question 19

What can be the effect of pressure on the normal pituitary (hypopituitarism)? [2]

Answer 19

cortisol deficiency which could be fatal / pale, no body hair, central obesity, wrinkly skin

Question 20

What are the effects of a functioning tumour (hyperpituitarism)? [P4, A4, C3]

Answer 20

1. prolactinoma - increased prolactin / increased milk production (galactorrhoea) / reduced fertility and amenorrhoea
2. acromegaly - increased GH / enlarged organs / increased risk of heart disease
3. Cushing’s disease - increased ACTH leading to excess cortisol / central obesity and “lemon on sticks” appearance, purple stretch marks (striae)