BIOL 320: Chapter 18 (1/23 pt 1)

What releases growth hormone from the anterior pituitary?

GHRH from hypothalamus

What inhibits secretion of GH?

GHIH: somatostatin

What is a direct effect of GH?

lipid metabolism in adipocytes

What is an indirect effect of GH?

causes liver and skeletal muscles to produce somatomedins: IGFs

What variables regulate GHRH secretion?

low blood glucose

stress

exercise

What horomones control GH?

GHRH and GHIH

Is GH a neurohormone?

yes

How does GH affect the adipose tissue?

lipolysis

How does GH affect the liver directly?

gluconeogenesis

How does GH indirectly affect the liver?

creates IGFs which go to bone and muscle

What does IGF do in bone and muscle?

bone: growth in bone length

muscle: growth in protein synthesis

Is the control of GH negative or positive feedback?

negative

Who experiences the highest amounts of GH?

children and adolescents

When are peak GH levels in the day?

24th hour of day into sleep

Is there a circadian rhythm to GH?

yes

Why do children need lots of sleep?

GH secretion tends to be highest when sleeping

What are the symptoms of pituitary dwarfism?

short stature

normal bones and intelligence

What happens when you make too much GH as an adult?

acromegaly: enlarged feet and face bones

What happens when you make too much GH as a child?

gigantism

Why does hyperglycemia occur in patients with acromegaly?

GH leads to glucose sparing: excess glucose is retained