Lect 23 Flashcards
Growth hormones has indirect effects on growth through what hormone
- Insulin-like growth factor
function of Insulin-like growth factor
- stimulates linear growth of bones
- hypertrophy and hyperplasia of tissues
are levels of GH higher in children, adults, or elderly
- highest in children
- decline with aging
what does decline of GH lead to in the body
- loss of lean body mass, fitness, protein synthesis, metabolic rate
When are levels of IGF-1 highest in a person’s lifespan
pubertal peak rate of growth
a GH secreting pituitary adenoma can lead to GH excess which can cause what condition?
- acromegaly
- occurs after puberty when linear growth is complete
- increase in bone size, organ size, hand and foot size, enlargement of tongue
- occurs after puberty when linear growth is complete
acromegaly occurs with GH hypersecretion when epiphyses are ? This results in
- closed in adults
- results in
- bone and soft tissue deformities
- increased protein, decreased fat content
- propensity to be diabetic
what condition can occur if GH excess occurs before puberty
- gigantism
- increased linear grwoth because of stimulation of epiphyseal plates
what is hypopituitarism
deficiency of one/more anterior pitiuitary hormones
what is panhypopituitarism
deficiency of ALL anterior pituitary hormones
List some effects of panhypoituitarism
- adrenal cortex atrophies: secretion of sex hormones decreases
- gonads atrophy: amenorrhea, impotence in men
- thyroid atrophies: cold intolerance, dry skin, mental dullness
- sensitive to stress: (illness, surgery, trauma)
GH deficiency in children can lead to
- failure to grow, short stature
- mild obestiy
- delayed puberty
GH deficiency before puberty results in what condition
Dwarfism
- defects:
- GH secretion, reduced IGF
African pigmy have what defect
- normal GH levels but do not exhibit the normal rise in IGFs with puberty
what is Laron dwarfism
- GH resistant
- genetic defect in expression of GH receptor
- do not produce IGFs in response to GH
GH/IGF-1 alone are not wholly responsible for growth, what role does the thyroid hormone have
- permissive role in skeletal growth
- critical in CNS growth
what role do steroids have in growth
- role in prepubertal growth
- promote weight gain and increase in muscle mass
hyperinsulinemia during pregnancy can result in
- increased fetal growth
- insulin deficiency during childhood will diminish growth
muscle protein synthesis occurs how long after resistance exercise
hours to days
both exercise and stimulate muscle protein synthesis
amino acids
does insulin play a role in muscle protein synthesis
yes
What myokine has an important role in regulating muscle and bone growth and collagen synthesis
IL-6
When is Myostatin levels increased? effect?
- elevated levels with stressful conditions (CA, disease)
- negative regulator of muscle growth
- elevated levels suppress bone formation
myostatin is derived from
skeletal muscle
glucocorticoids have what effect on myostatin
- stimulate it
- thus glucocorticoid administration to children inhibits growth
muscle contraction (exercise) stimulates the release of what myokines that alter bone metabolism
- IL-6: increases osteoclast activity
- leukemia inhibitory factor (LIF): stimulates bone formation
- IGF-1
- fibroblast growth factor (FGF-2): stimulate bone formation
Brain-derived neurotrophic factor (BDNF) has what function
- secreted by brain to promote growth and maintenance of neurons
- role in learning and memory
Brain-derived neurotrophic factor (BDNF) is also produced where
- skeletal muscle
- increased production with contraction of skeletal muscle
