Control of growth

Question 1

Describe the synthesis of growth hormone

Answer 1

neurons in arcuate nucleus of hypothalamus secrete growth hormone releasing hormone (GHRH) into hypophyseal portal blood

GHRH binds to G-protein coupled receptor on somatotrophs and activates G alpha s, which in turn activates guanylyl cyclase

increase in cAMP leads to gene transcription and synthesis of GH

Question 2

Which hormone stimulates growth hormone production?

Answer 2

growth hormone releasing hormone

Question 3

Which hormone inhibits growth hormone production?

Answer 3

somatostatin (SST)

Question 4

When does growth hormone secretion occur?

Answer 4

pulsatile fashion every 2 hours
maximal release at night

Question 5

Direct effects of growth hormone

Answer 5

adipose tissue - causes release of fatty acids from adipose tissue

promotes gluconeogenesis and glycogenolysis

insulin resistance - decreases glucose uptake and utilisation by target tissues, produce an increase in blood glucose conc, stimulates the release of more insulin