Pituitary Physiology

Question 1

how is pituitary involved in thyroid function?

Answer 1

cold exposure causes hypothalamus to produce thyrotropin releasing hormone which stimulates anterior pituitary to produce thyrotropin which stimulates the thyroid to produce thyroxin

Question 2

how is the thyroid involved in sex hormone production?

Answer 2

hypothalamus produces GnRH (gonadotrophin releasing hormone) which stimulates anterior pituitary to secrete LH and FSH which either causes testes to produce testosterone or ovary to produce oestrogen and progesterone

Question 3

how is the pituitary involved in cortisol production?

Answer 3

hypothalamus secretes corticotrophin releasing hormone which causes pituitary to secrete ACTH which causes adrenal gland to secrete cortisol

Question 4

what is the main control factor in prolactin production?

Answer 4

dopamine from the hypothalamus inhibits prolactin secretion

Question 5

describe the paired hormone concept?

Answer 5

pituitary/central hormone drives secretion of another peripheral hormone
i.e - ACTH secretion from the pituitary drives secretion of cortisol from the adrenal glands

Question 6

what is included in a usual pituitary blood test?

Answer 6

TSH, thyroxine
LH/FSH, testosterone/E2
GH
prolactin

Question 7

give 4 examples of paired hormones?

Answer 7

ACTH - cortisol
TSH - thyroxine
LH/FSH - testosterone or estradiol
GH - IGF1

Question 8

give 3 examples of stimulation tests which can be used in dynamic pituitary testing?

Answer 8

synacthen (checks cortisol)
insulin stress test/prolonged glucagon test (cortisol and GH)
water deprivation (serum and urine osmolalities - stimulates ADH production)