20 Questions
Which receptor family do growth hormone cell surface receptors belong to?
JAK/STAT cytokine receptor superfamily
What is the primary mediator of the growth-promoting effects of growth hormone?
Insulin-like growth factor 1 (IGF-1)
Where is much of the circulating IGF-1 produced?
Liver
What role does growth hormone play in longitudinal bone growth?
Stimulates longitudinal bone growth until epiphyses close
In which tissues does growth hormone stimulate the production of IGF-1?
Cartilage and bone
What effect does growth hormone have on insulin sensitivity?
Reduces insulin sensitivity
In patients unable to respond to endogenous GH due to mutated GH receptors, how does IGF-1 affect serum glucose and insulin?
Lowers serum glucose and reduces circulating insulin
What is a common presentation of GH deficiency in childhood?
Short stature and adiposity
What are the effects of GH on lipid and carbohydrate metabolism throughout postnatal life?
Affects both lipid and carbohydrate metabolism
Why are neonates with isolated GH deficiency of normal size at birth?
Because fetal GH is not required for prenatal growth
What is the primary mediator of the growth-promoting effects of growth hormone?
IGF-1
How does growth hormone affect body composition?
Promotes an increase in muscle mass
Which receptor-associated proteins are involved in the signaling cascades of growth hormone?
JAK tyrosine kinases and STATs
When does longitudinal bone growth stop under the influence of growth hormone?
Near the end of puberty
Where is much of the circulating IGF-1 produced?
Bone, cartilage, muscle, and kidney
What effect does growth hormone have on insulin sensitivity?
Reduces insulin sensitivity
In patients who are unable to respond to endogenous GH due to mutated GH receptors, how does IGF-1 affect serum glucose and insulin?
Lowers serum glucose and increases circulating insulin
What can cause growth hormone deficiency in individuals?
Hypothalamus damage by a tumor
What is a key characteristic of GH deficiency in childhood?
Short stature and adiposity
How does IGF-1 primarily act in patients with mutated GH receptors?
Both through its IGF-1 receptors and through insulin receptors
Learn about the effects of growth hormone on body composition, including its role in mediating insulin-like growth factors and the consequences of GH deficiency in childhood and adulthood.
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