Lecture 23 - Growth and Development Flashcards
causes of psychosocial dwarfism
abuses and traumas might affect release of GHRH, impairing growth
what causes reduced GH of dwarfism
some tumors, radiation damage, inflammation of pituitary
insensitivity of GH:
Laron’s dwarfism
mutation of GH receptor:
hypoglycemia
hypercholesterolemia
obesity
insensitivity to GH:
pygmies
severe under-expression of GH receptor
Gigantism
pre-pubertal pitutiary tumor: linear growth
Acromegaly
post-puberty pituitary tumor:
radial growth
clinical considerations of GH therapy:
controversial
GH for children that are short but have normal Gh
GH and sport
GH replacement for elderly subjects
GH stimulates bones…
IGF-1 stimulates paracrine action which increases condrocytes at epiphyseal plates and increases cacrtilage and bone which results in linear growth before puberty and radial growth after puberty
GH stimualtes liver to release
IGF which acts in endocrine fashion all over the body where 90% of it is bound to plasma protein thus to increase protein synthesis and cell division
what inhibits IGF secretion by liver?
malnutrition
hypothyroidism
low insulin
GH effects on growth
most of the effects depend on the synthesis of IGF-1 and on the GH-IGF-1 synergism
GH’s metabolic effects
- increase plasma glucose
* anti-insulin: decreases consumption of glucose in muscle and fat
* increase gluconeogenesis - promotes use of fatty acids
* increase lipolysis - promotes protein synthesis
* increase uptake of AA
* increase number of ribosomes
stimuli of GH release
GHRH from hypo
sleep
some cortisol and TH
Ghrelin
hypoglycemia, elevated AA, low free fatty acid levels
sex steriods
exercise
if you want to grow, eat steak not cake!
inhibitors of GH release
somatostatin from hypo
elevated IGF-1 and GH
high cortisol
hyperglycemia, high free fatty acid levels, obestiy
hypothyroidism (no TH is bad)
rise in sex steroid at pubtery
promotes release of GH
