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Block 11 Physiology of Growth

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klau253's version from 2017-05-20 16:57

Mediators of growth

Question Answer
Growth Hfrom Ant. pit, act thru insulin growth factor
IGF production siteliver, kidneys, muscle, cartilage, bone
IGF-Iindependent of GH before birth, stimulated by GH after birth, peaks in puberty
IGF-IIlargely indepedent of GH
overexpression of IGF-IIgrowth problem in tongue, muscles, kidney, heart and liver
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GH regulation
Question Answer
Somatostatininhibits ant. pit.
GHRHstimulates Ant. pit
Factors that stimulate somatostatinbeta-2 adrenergic, FFA, glucose, glucocorticoids
Factors that inhibit somatostatinarginine, dopamine, serotonin, ACh, Ghrelin
Factors that stimulate GHRHalpha-2 ,galanin, GABA, ghrelin, sex steroids
Factors that stimulate growth Hghrelin, thyroid H, glucocorticoids
IGF-1 functionsuppresses ant. pit to decrease GH release, suppresses GHRH, stimulates somatostatin
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Thyroid H
Question Answer
Functionprotein synthesis in brain, maturation of skeleton and nervous tissue, growth of bone
Cretinisminadequate levels of thyroid H leading to mental retardation
Insufficiency can causeDecreased cerebral neurons, reduced branching of dendrites, decreased in myelination, reduced cerebral blood supply
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Corticosteroids
Question Answer
Cortisolif excess can inhibit growth
glucocorticoidsinterferes with cartilage and bone synthesis
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Sex steroids
Question Answer
Girlsoestradiol-17beta from ovaries + GH
Boystestosterone from leydig cells + GH
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disturbances of growth

Achondroplasia
Question Answer
What happensauto dom, mutation in fibroblast growth factor receptor 3 (FGFR3)
Results of mutationdecreased endochondral ossification, decreased chondrocytes in growth plate, decreased cellular hypertrophy and cartilage matrix production
Featureslarge head with prominent forehead, short arms and legs
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Acromegaly
Question Answer
What happenshypersecretion of GH
Common causeadenoma of pituitary somatotroph cells
Featuressjull growth, cardiomyopathy, prognathism, type 2 DM, colon CA
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Pituitary dwarfism
Question Answer
What happensGH deficiency
Causespituitary/hypothalamic tumors, infections (meningitis, syphilis), pit. infarction, head trauma
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Question Answer
Laron dwarfismlow serum IGF and IGF binding protein
Panhypopituitarismabsence of all the pit. H
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Hypothyroidsm
Question Answer
Causesdefect in thyroid gland fxn, decreased TSH/TRH, iodine deficiency
Cretinismphysical and mental retardation due to congenital hypothyroidism
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