Normal Growth and Clinical Aspects Flashcards
Where is growth hormone released from?
Anterior pituitary
What is growth hormone also known as?
Somatotrophin
What is the intermediate associated with growth hormone?
IGF-I (insulin-like growth factor-I)
Where is IGF-I secreted from?
Liver
What is the function of IGF-I?
Secreted in response to GH release from anterior pituitary. Controls GH release through a negative feedback loop.
What is the effect of GH/IGF-I on bone?
GH stimulates chondrocyte precursor cells in epiphyseal plates
IGF-I acts as autocrine or paracrine agent to stimulate differentiating chondrocytes to undergo cell division and produce cartilage.
What are the direct effects of growth hormone?
Increases gluconeogenesis by the liver
Reduces ability of insulin to stimulate glucose uptake by muscle and adipose tissue
Makes adipocytes more sensitive to lipolytic stimuli
Increases muscle liver and adipose tissue amino acid uptake and protein synthesis
How is growth hormone secretion controlled?
Hypothalamus
What are the stimuli that increase GHRH secretion?
Actual or potential decrease in energy supply to cells
Increased amounts of amino acids in the plasma
Stressful stimuli
Delta sleep
Oestrogen and androgens
What are the stimuli that increase GHIH?
Glucose
Cortisol
FFS
REM sleep
What factors affect growth?
Hormones
Nutrition
Genetics
What effects do thyroid hormones have on growth?
Ossification of cartilage and teeth maturation
What are the periods of rapid growth in humans?
Infancy
Puberty
What is caused by hyper secretion of growth hormone?
Gigantism
Acromegaly
What is the difference between gigantism and acromegaly?
Gigantism: GH due to pituitary hormone BEFORE epiphyseal plates of long bones close
Acromegaly: GH due to pituitary hormone AFTER epiphyseal plates of long bones close
