Regulation of Growth Flashcards
During what periods of life do your 2 growth spurts occur?
Postnatal
Pubertal
GH/IGF-1, TH and steroids regulate what general changes in the body?
Growth and maturation
Thyroid deficiency leads to abnormal what in cretinism (congenital hypothyroidism)?
Abnormal growth and development
During what growth spurt does GH peak?
Puberty
What is the relationship between GH and IGF-1 at puberty?
Parallel each other
Decreased/constant levels in adulthood maintain what?
Lean body mass
Will GH levels remain constant, increase or decrease during senescence?
Remain constant
GH release increases in what 3 scenarios leading to pulsatile release?
↑ after exercise
With food restriction
During sleep
What hormone is responsible for GH release?
GHRH
What hormone is responsible for inhibiting GH?
GHIH (somatostatin)
Gs targets what in the following pathway?
Gs → X → PKA → CREB signaling → PIT1 → GH/GH receptor regulation→ growth and development
Adenylyl cyclase
What pairing of hormones will promotes long bone growth until closing of the epiphyseal plate?
GH & IGF-1
What class of hormones will signal to close the epiphyseal plate at the end of puberty?
Sex steroids
Is the following a direct or indirect pathway of growth?
Stimulation of liver → IGF-1 (somatomedin) → ↑ protein synthesis, cell division, & bone growth
Indirect
Why is IGF-1 a better measurement of GH release vs measuring GH levels?
IGF-1 w/ longer half life
Is the following a direct or indirect pathway of growth?
binding to receptors in tissue → intermediary fuel metabolism/ metabolic actions (unrelated to growth) → ↑ fat breakdown and glucose output by liver & ↓ glucose uptake by muscles
Direct
↑ GH & IGF-1 will have what effect on? GHRH
↑ GH & IGF-1 → negative feedback on GHRH (↑ GHIH)
Is GH release constant or situation dependent?
Situation dependent
↑ dietary protein leads to what effect on GH, IGF, and insulin?
What impact does this have on growth and caloric storage?
↑ GH/ IGF/ insulin
↑ protein anabolism/ growth
Little to NO change in caloric storage
↑ dietary carbs (hyperglycemia) leads to what effect on GH, IGF, and insulin?
What impact does this have on growth and caloric storage?
↓ GH
no change in IGF
↑ insulin
NO change in protein synthesis or growth
↑ caloric/ CHO storage
In a caloric deficiency you have high GH, but no growth. Why is this?
↓ ICGF-1 → ↓ protein anabolism, growth
What is X?
↑ GH & cortisol → ↑X → ↓ IGF-1 bioavailability to tissues → diverts GH → no growth (instead caloric mobilization)
IGF-BP3
Does hyperglycemia result in increased or decreased GH?
Decreased
Hypoglycemia → ↑ GH, ↓ insulin leads to what three caloric mobilization processes?
- ↑ lipolysis
- ↑gluconeogenesis
- ↓ peripheral glucose uptake
Low or high levels of cortisol have what effect on GH?
decreased GH secretion
What impact will a normal/ median range of cortisol production have on GH?
Steady GH secretion
T and GH in the liver enhance the secretion of what hormone?
IGF-1
Does T or E have more growth effects?
T
Will E (in the liver) increased or reduce IGF-1 secretions?
Reduce
IN the absence of TH, will GH be able to produce growth?
No
T or F: TH has an indirect effect on GH?
Indirect
The following are the effects of what hormone?
- ↑ metabolic needs prior to tissue accumulation
- Facilitates linear growth of bone
- Tooth development & eruption
- Growth/maturation of epidermis, hair follicles, nails, alteres subQ tissues
- Prolactin secretion and mammary gland development
Thyroid hormone
What hormones increases cartilage chondrocyte activity in the growth plate and accelerates bone turnover
Thyroid hormone
Thyroid receptors in the the osteoblasts stimulate bone remodeling via what
GF’s IL6/ PGE2 and IGF1 receptor
Does exercise increase glucose uptake in the cells with or without insulin present?
Without
insulin and diet facilitate muscle protein synthesis via what signaling pathway?
MTORC-1
What inhibits MTORC-1? (3)
Myostatin
Glucocorticoids
Cytokines
A deficiency in myostatin will lead to what with regard to the muscles?
Hypertrophy
Will increased protein intake w’o conditioning/training lead to muscle synthesis?
Yes
↑ linear growth due to excessive stimulation of GH at epiphyseal plate will lead to what disease?
Gigantism
Chronic excess GH in the absence of linear bone growth is what disease?
Acromegaly
Bone/ST deformities, enlarged hands and feet, thick skin, ↑ protein, ↓ body fat, vision changes, HA, hyperglycemia/DM are sx of what disease?
Acromegaly
What imaging study will be used to dx a somatotrop adenoma resulting in acromegaly
Pituitary MRI
↑ IGF-1, OGTT > 1 ng/mL is dx for what disease?
Acromegaly
A GH deficiency will lead to what disease?
Dwarfism
If pt becomes GH deficient in adulthood what are the effects?
Asx
OR
↓ skeletal muscle mass/ bone density, ↑ HF risk, old age sxs
Lack of GHRH, pituitary insufficiency, tissues unresponsive to GH, IGF-1 deficit, failure to produce IGF-BP3 will lead to GH excess or Gh deficiency?
GH deficiency
With Laron dwarfism what receptor is deficient?
GH receptor
The Pygmies of Cameroon have a deficit of what hormone?
IGF-1 deficit
