normal GH axis

Question 2

Single chain protein with______disulphide bonds

Answer 2

2

Question 3

Growth hormone receptor: ___ long antiparallel alpha helices structurally related to________GH can also activate_________ receptors

Answer 3

• 4• leptin, cytokine receptors: ILs, EPO• lactogenic

Question 4

human GH locus on chromosome 17HS 1 and 2 are_______specificHS 4 is____________ specificHS 3 and 5 are both

Answer 4

• pituitary• placenta• pituitary and placenta

Question 5

GH receptor signalling uses___________GH + 2 receptors forms___________complexshed extracellular domain can also act as

Answer 5

• JAK2/STAT5 pathway. acts as nuclear TF•also activates via MAPK and PI3•ternary• circulating GH binding protein

Question 6

Metabolic actionsincrease: ____ and ____decreases___other action: increases_____from liver

Answer 6

1. lipolysis and protein synthesis2. glucose metabolism, opposing insulin3. IGF-1 production

Question 7

GH, indirectly via IGF-1: growth promotionincreased clonal expansion of _____GH acts on fibroblasts, fat cells and osteoblasts

Answer 7

chondrocytes

Question 8

local aromatase found in growth plates. What closes the growth plate in boys and girls?

Answer 8

oestradiol

Question 9

What decreases GH secretion? (4)

Answer 9

1. somatostatin2. glucose3. free fatty acids4. glucocorticoids: cortisol

Question 10

What increases GH secretion? (5)

Answer 10

1. GHRH2. estradiol, testosterone3. arginine4. T3/T45. sleep, exercise

Question 11

what sensitizes somatotrophs to GHRH?

Answer 11

androgens and oestrogens–> pubertal rish in GH and growth spurt

Question 12

how do you measure GH?

Answer 12

immunoassay: ELISA; v precise and sensitive but does not measure bio potency directlybioassays: measure potency of new batches of rGH./ NOT for checking patients GH– insensitive