Control Of Growth Flashcards
What influences growth?
Genetics
Environment
Nutrition
Hormones
What is the action of growth hormone?
Stimulates long bone growth in children and teenagers
In adults;
Maintain muscle and bone mass, promote healing and tissue repair, modulates metabolism and body composition
What is the effect of GH on cells?
Acts on Janus kinases
Causes activation of transcription factors and IGF
What controls GH secretion?
Main control is from hypothalamus
GHRH - stimulates GH
Somatostatin - inhibits GH
What are the two types of IGF?
IGF2 - mainly in adults
IGF1 - mainly in foetal growth
What is the action of IGF?
Stimulates bone and cartilage growth in children and teenagers
In adults;
Maintain muscle and bone mass, promote healing and tissue repair, modulates metabolism and body composition
What actions are modulated by IGF?
Hypertrophy
Hyperplasia
Increase rate of protein synthesis
Increase rate of lipolysis
What results from GH deficiency in children?
Pituitary dwarfism
Proportionate, responds to GH therapy
What results from GH excess in children?
Gigantism
Often from pituitary adenoma
What results from GH excess in adults?
Acromegaly; large extremities
Describe long loop feedback of GH
Mediated by IGF
Inhibition of release of GHRH
Stimulates release of somatostatin
Therefore inhibits release of GH
Describe long loop feedback of GH
Mediated by GH
Stimulates somatostatin release
Therefore inhibits GH release
