176 growth and development Flashcards Preview

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Flashcards in 176 growth and development Deck (16):
1

phases of growth

fetal - fast, different mechanism, independent of fetal pituitary; Insulin/IGF is major regulator; need good placenta

infancy/childhood - major regulators GH and T3/4

adolescent - regulated by hypothalamic - pituitary - gonadal axis (sex steroids produce phsyical changes)

2

major regulator of fetal growth?

insulin - babies born to DM mothers are big becuase glucose crosses placenta and thus kids make more insulin

endocrine regulators (GH, T3/4) dont matter in utero - born normal size BUT IGF-1 does matter

3

leprechaunism

make insulin but bad receptor - very small in utero

4

major regulator on growth in infancy and childhood

GH and T3/4

5

GH affect on bone

increases osteoclast and OB activity - increases endochondral bone formation

promotes epiphyseal growth

6

what inhibits GH production? how in circulation?

somatostatin

50% bind to GH binding protein = thought to be extracellular part of receptors

7

when is GH secreted?

at night, during exercise, with food

8

primary fxn of GH in children?

linear growth via IGF-1 in target tissue

9

GH action

dimerize --> JAK/STAT pathway --> IGF mRNA production

10

most important GF for post natal growth?

IGF1 --> binds IGFBP-3 and travels to chondrocytes at epiphseal growth plate along with GH--> both bind receptors (GH causes local IGF production) --> IGF signaling pathway causes proliferative zone to increase cell production

11

at what point does growth correlate to adult height?

2 years

12

growth velocity

steady until peak at puberty followed by rapid drop off

13

abnormal growth warning signs

<3rd percentile
not following genetic potential
crossing percentiles after 2 years

14

definition of short stature

< -2 SD for age (~3% of kids)
doesn't mean something is wrong

15

do kids with primary growth abnormaliites (osteochondrodysplasia, downs, turners, etc) have normal growth rates?

yes, just shorter

normal skeletal age

16

secondary growth disorders (endocrine, malnutrution)
is linear growth rate normal?

secondary to another problem - malnutrution, chronic disease, endocrine issues

no - delayed skeletal age (younger) --> indicates potnetial for additional growth

endocrine issues - hypothroidism, cushing's syndrome (usually iatrogenic), IGF deficiency (anywhere along the axis of hypo - pit, GHRH receptor mutation, IGF resistance)