chapter 9 - growth hormone

Question 1

growth hormone (and prolactin) family of hormones

Answer 1

aka somatotropin hormone or somatotropic hormone
similar to prolactin and lactogen (placental)
secreted in pulsatile pattern - burst every 2 hours
secretory burst at puberty induced by estrogen or testosterone
hypoglycemia and starvation, exercise, some forms of stress (fever, trauma, anesthesia) stimulate

Question 2

feedback of GH secretion

Answer 2

hypothalamus releases GHRH
activates antior pituitary to release
GHRH has negative feedback on hypothalamus GHRH production
GH has positive feedback on hypothalamus somatostatin prod.
somatostatin inhibits GH release
target tissues release somatomedins (IGF)
these inhibit GH release in interior pituitary and increase somatostatin release in hypothalamus

Question 3

actions of GH

Answer 3

1: diabetogenic effect
2: increased protein synthesis and organ growth
3: increased linear growth

Question 4

diabetogenic effect

Answer 4

one of the effects of GH
causes insulin resistance
increases glucose uptake and utilization by muscle and adipose
results in increase in blood glucose concentration increases lipolysis metabolic effects result in increase in blood insulin

Question 5

GH effects on protein synthesis and organ growth

Answer 5

increases uptake of AA and stimulates synthesis of DNA, RNA, and protein in organsincreases lean body mass and increases organ size

Question 6

GH effects on linear growth

Answer 6

mediated by somatomedins
alters cartilage metabolism via stimulating DNA synthesis, RNA synthesis, and protein synthesisepiphyseal plates widenmore bone laid down at ends of long bonesincreased metabolism in cartilage-forming cells and proliferation of chondrocytes

Question 7

GH deficiency

Answer 7

results in failure to grow
short stature
mild obesity
delayed pubertycan be due to any step in HAP axis

Question 8

GH excess

Answer 8

causes acromegaly and giganticism in children
usually due to GH secreting adenoma in pituitaryin adulthood, increased periosteal bone growth, increased organ size, increased hand and foot size, enlargement of the tongue, coarsening of facial features, insulin resistance, glucose intolerancetreat wtih somatostatin analogues