Normal Growth and Clinical Aspects Flashcards
what is another name for somatotrophin
growth hormone
what is another name for somatostatin
growth hormone–inhibiting hormone
what is somatomedian also known as
IGF-1 (as it mediates growth)
where is growth hormone released from
the anterior pituitary
what type of hormone is growth hormone
peptide hormone
why is it not possible to use GH from animals to treat disease in humans
GH is species specific
GH will only stimulate growth under the permissive action of which two hormones
thyroid hormones
insulin
why do children with untreated hypothyroidism or poorly controlled diabetes have stunted growth despite having normal GH levels
as GH requires thyroid hormones or insulin to stimulate growth
GH achieves its effects on cell division by an intermediate, what is this intermediate called
IGF-I (insulin-like growth factor-I)
what secretes IGF-I
liver
what is GH effect on bone
GH stimulates chondrocyte precursor cells in the epiphyseal plates to differentiate into chondrocytes
once GH hormone has stimulated chondrocyte precursor cells what do they begin to secrete
IGF-I
what effect does IGF-I have on differentiating chondrocytes
stimulates differentiating chondrocytes to undergo cell division and produce cartilage (the foundation for bone growth)
what causes the epiphyseal plates to close during adolescence
plates close under the influence of sex steroid hormones
what are the “direct” effects of GH
increases gluconeogenesis by the liver
Reduces the 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
what effect does insulin have on protein synthesis
increases protein synthesis
what effect does insulin have on aa acid uptake
increases amino acid uptake
what effect does insulin have on glucose uptake
increases glucose uptake
what effect does GH have on protein synthesis
increases protein synthesis
what effect does GH have on aa acid uptake
GH increases aa acid uptake
what is GHRH
growth hormone releasing hormone
what is basal [GH] in plasma
0-3ng/ml (in children and adults)
what is the 24 hour mean of basal [GH] in plasma in adults
2-4ng/ml
what is the 24 hour mean of basal [GH] in plasma in children
5-8ng/ml
what type of hormones are GH and IGF-I
peptide
how are GH and IGF-I transported in the blood
they are transported in the blood with a binding protein
what percentage of GH is in the bound form
50%
what are stimuli that increase GHIH (a.ka somatostatin)
glucose
cortisol
FFA
REM sleep
in the foetal period and the first few months of life what factor largely controls growth
nutritional intake
after the first 8 months of life what hormone becomes a predominant influence on the rate at which children grow
GH
what are stimuli that increase GHRH secretion (increase GH)
- actual or potential decrease in energy supply to cells
- increased AA in the plasma
- stressful stimuli
- delta sleep (growth during sleep , repair in adults)
- oestrogens and androgens
what is the importance of growth hormone during foetal life
minor, babies born deficient in GH and IGF-1 are of normal size
how important is thyroid hormone in utero and childhood
essential particular in development of the nervous system
what is cretinism
children are BORN hypothyroid, they have retarded growth because they have loss of TH permissive action on GH
what will be GH levels in a person who has cretinism
GH levels are normal
what is giantism
excess GH due to a pituitary tumour BEFORE epiphyseal plates close
what is acromegaly
excess GH due to a pituitary tumour AFTER epiphyseal plates close
