Normal Growth and Development Flashcards
what releases somatotrophin?
the anterior pituitary
what does GH (GROWTH HORMONE) require to stimulate growth?
permissive actions of thyroid hormone and insulin
true or false:
GH is a peptide hormone
true
how does GH promote growth?
through hypertrophy and hyperplasia
what does the liver produce in response to growth hormone?
somatomedian or IGF-1
describe the negative feedback loop that IGF-1 is involved in
> inhibits growth hormone releasing hormone
stimulates somatostatin
inhibits growth hormone release from pituitary
what does IGF-1 stimulate in the bone?
chondrocyte pre-courser cells (prechondrocytes) in the epiphyseal plate to differentiate into chondrocytes
what is the effect of differentiating prechondrocytes on IGF-1?
> increased IGF-1 secretion
>increased IGF-1 responsiveness
what acts as an auto/paracrine agent on chondrocytes to cause cell division and cartilage production?
IGF-1
why does the epiphyseal plate close during adolescence?
due to the influence of sex steroid hormones
what are the diabetogenic effects of growth hormone?
> increased glucogenesis by the liver
reduced ability of insulin to stimulate glucose uptake by muscle and adipose tissue
increases adipocyte sensitivity to lipolytic stimuli
what are the anabolic effects of growth hormone?
increases muscle liver and adipose tissue amino acid uptake and protein synthesis
what change in GH occurs in delta sleep in children?
there is approximately 20% increase in secretion
what stimulate GH release?
> stressful stimuli > actual/potential decrease in energy supply to cells > increased amino acids in plasma > delta sleep > oestrogens and androgens
what inhibits GH hormone release?
> glucose
free fatty acids
REM sleep
cortisol
what three factors effect growth?
> hormones
nutrition
genetics
true or false:
GH and IGF-1 have a large impact in growth during foetal life
false they have a minor impact
at what time do androgens and oestrogens dominate the growth spurt?
puberty
what hormone dominates uterine growth?
insulin (with IGF-2)
what are the growth effects of thyroid hormone?
> permissive to IGF-1
ossifies cartilage
mature teeth
contours face and proportions body
what is cretinism?
hypothyroidism from birth:
> stunted growth
why do injury and disease stunt growth?
they lead to increased protein catabolism
true or false:
gigantism is due to a pituitary tumour BEFORE epiphyseal plates fuse
true
true or false:
acromegaly is due to a pituitary tumour BEFORE epiphyseal plates fuse
false this is after plates have sealed
what can cause dwarfism?
> GHRH deficiency > abnormality in GH secreting cells > end organ unresponsiveness to GH > genetic mutations: impairment of cells to produce IGF-1 > precocious puberty > hypothyroidism
why dose precocious puberty cause dwarfism?
there is excess GHRH which stimulates puberty and promotes sex hormone release. this causes long bones to fuse creating stunted growth.