Metabolic rate, growth and disease Flashcards
Growth hormone effects
Children: deficiency- dwarfism excess-gigantism
Adults: deficiency- no obvious disease excess= acromegaly
Growth hormone regulation
Hypothalamus
GHRH increases and somatostatin suppresses secretion from anterior pituitary
Target organs release IGFs to provide feedback inhibition
GH action
acts via tyrosine kinase associated receptor –> protein phosphorylation–> diabetogenic effects- liver increases gluconeogenesis, increase lipolysis, muscles- decrease glucose uptake (more for brain)
What stimulates GHRH
low glucose
amino acids, TRH and ghrelin
Thyroid Hormones
T3 (1 tyrosine) and T4 production and release stimulated by TSH.
rT3= inactive
T4–> T3= 2 enzymes (type 1- in liver/kidney/ thyroid type 2- in pituitary/CNS/ placenta)
Thyroid hormone effects
increase gluconeogenesis, glycogenesis , increase lipolysis, proteolysis increase Na/K/ATPase activity
Chronic: infants–> dwarfism and cretinism later childhood-impairment of growth
Glucocorticoids
hypothalamus integrates stress factors and diurnal rhythms to release CRH–> induces ACTH release from ant pituitary –> stimulates adrenal cortex –> hypertrophy and cortisol release
act via nuclear receptor to induce gene transcription
Glucocorticoids acute effects
inhibit insulin responses and enhance SNS responses –> target glucose to brain and other organs use fats
in liver promotes gluconeogenesis and glucose release
In fat: lipolysis
Min muscle: protein breakdown for FFA
Glucocorticoids chronic effects
immunosupression, reduced inflammation, stimulate haematopoiesis, fat redistribution to centre, skin thinning, muscle wasting, osteoporosis
excess–> cushings
insufficiency –> Addison’s disease