Endocrine control of growth Flashcards
3 types of growth
normal, catch-up, compensatory
Phases of normal growth
fetal (rapid), postnatal, pubertal, adulthood, senscent (may be a decline)
What is required for normal growth?
proper nutrition, sufficient hormones, good psychosocial enviornment
Hormones involved in prenatal growth which grows to 30% of adult growth?
insulin, hpL
Hormones involved in infantile growth which lasts 0-1 years
insulin
Hormones involved in junvenile growth which lasts 1-12 years and 85-88% of adult height
insulin, hGH, T3, VD
Hormones involved in adolescent growth
insulin, hGH, T3, sex steroids, VD
What does excess GH cause?
increase linear growth, normal skeletal maturation, but an increased affect on adult stature. Gigantism, increase to genetic potential?
What does deficiency in GH cause?
decrease linear growth, delayed skeletal maturation, increase dwarfism (hyposomatotropic dwarfism)
What does excess TH cause?
slight increase in linear growth, slight advance in skeletal maturation, minimal effect on adult stature
What does TH deficiency cause
decrease linear growth, delayed skeletal maturation, negative affect of adult stature
What does cortisol excess cause?
decreased linear growth, delayed skeletal maturation, negative affect on skeletal maturation
What does androgen excess cause?
increase followed be decrease in linear growth, advanced in skeletal maturation, negative effect on adult stature
What does androgen deficiency cause?
increase linear growth, delayed skeletal maturation, eunuchoidal (tall with long arms and legs)
What does rx with low dose estrogen cause?
increase linear growth, normal skeletal maturation, normal adult stature
What does rx with excess/moderate dose estrogen cause?
increase linear growth than decrease, advanced skeletal maturation, decreased adult stature
What does estrogen deficiency cause?
increase in linear growth, delayed skeletal maturation, increased adult stature
What is somatotropin?
GH
What is somatomedin?
SM-C/ IGF-1–> mediates some of GH actions on bone elongation and adipocytes
What is somatostatin?
hypothalamic peptide that inhibits GH secretion
What is somatocrinin?
hypothalamic peptide that stimulates GH secreation (GHRH)
What are the 2 structural forms of GH and what is the difference?
22K: 90% of GH, growth promoting + other metabolic actions
20K: 10% of total GH and mainly growth-promoting
What does isolated GH deficiency?
hyposomatotropic dwarfism
When does GH exert its major action on body mass?
juvenile and pubertal periods
When does GH exert its major action on tallness?
juvenile and pubertal periods only, synergism with then antagonism by gonadal steroids
Where does GH exert its major action on long bone growth?
epiphyseal growth plate
Secretory pattern of GH
episodic, ultraradian
Physiological causes of increase GH
GHRH, decreased SS, spontaneous, deep sleep, exercise, acute stress, thyroid hormone, puberty, post-prandial decrease in glucose
Physiological causes of decrease GH
SS, decreased GHRH, spontaneous, light sleep and waking, elevated GH, IGF1, aging, postprandial hyperglycemia, increased FFA
Pharm. path, provocative causes of increased GH
GHRH, estrogens, hypoglycemia/ insulin, Arg/Leu, starvation, pituitary tumor
Pharm/path/provocative causes of decreased GH
SS analogs, GC, hyperglycemia, hypothyroidism, hyperthyroidism, pituitary tumor, progesterone
