Exam 1 - Human Growth Hormone

which tropic cell does Growth Hormone Releasing Hormone (GHGH) stimulate? what mechanism does this process use

somatotrophs

phospholipase C

adenylyl cyclase

what hormone inhibits somatotrophs

growth hormone inhibiting hormone/somatostatin

what do somatotrophs secrete? what mechanism does it use?

human growth hormone (hGH)

tyrosine kinase

what nucleus in the hypothalamus makes GHRH

arcuate nuclei

what stimulates GHRH to be released (7)

exercise

emotional and physical stress

hypoglycemia

increase AA

decreased FFA concentration

testosterone

estrogen

thyroxin

what stimulates somatostatin/GHIH

GH

high IGF-1 levels

hyperglycemia

high FFA concentration

obesity

senescence

pregnancy

what kind of hormone is hGH

protein

t/f

hGH is secreted at a constant rate all day

false it happens in bursts of roughly 2 hours

when is the largest burst of hGH secreted

within 1 hour of sleep

the hGH that doesn't circulate in the blood goes to what other locations

liver, bone, skeletal muscle, and adipose tissue

what does hGH stimulate in the liver

glycogenolysis, gluconeogenesis, IGF-1 production to increase blood glucose

what does hGH stimulate in skeletal muscle

increase AA uptake for protein synthesis

increase glucose uptake via IGF-1

what does hGH do in the bone

increase AA uptake for prot. synthesis

increase glucose uptake via IGF-1

chondrogenesis for bone growth

increase bone mineral density

what does hGH do in adipose tissue

increase lipolysis to convert TG into FFA and glycerol which goes to the liver for gluconeogenesis

how does the body react when in a hypoglycemic response in reference to hGH

hypoglycemia $ GHRH -> hGH -> increases blood glucose via $ liver for gluconeogenesis and glycogenolysis

($= stimulate)

what receptors does IGF-1 bind to in order to increase glucose uptake

insulin

what affects does IGF-1 have on bones

increases osteoblasts and osteoclasts

the increase in osteoclasts and osteoblasts in bones via IGF-1 causes increases in what processes

endochondral ossification and protein synthesis of type I collagen

what effect does IGF-1 have on cartilage at the epiphyseal plates

increase size, differentiation, proliferation of chondroblasts

what function does hGH have on plasma calcium? how does it do this?

increase via intestinal absorption of calcium

what effect does hGH have on immune response? how?

increase by increasing the number of structures to produce antibodies

what effect does hGH have on oxygen transport? how?

increase via increasing the synthesis of EPO

which pathologies of hGH are associated with children

- Growth Hormone Deficiency (GHD)/pituitary dwarfism

- gigantism

which pathologies of hGH are associated with adults

- Adult Growth Hormone Deficiency (AGHD)

- Acromegaly

does GHD/pituitary dwarfism cause intellectual disability?

no

what is a treatment for GHD/pituitary dwarfism

injections of synthetic hGH

which pathologies of hGH can be caused by tumors

GHD and Gigantism

does the tumor causing gigantism lead to under or overproduction of hGH? what is this tumor of?

over

somatotrophs

what are some treatments for gigantism

removal of tumor, radiation, medications

"stalk effect" is part of which pathology? what is it?

gigantism

tumor compressing pituitary stalk leading to disruption of dopamine -> lactation

is acromegaly an over or underproduction of hGH

overproduction

how is an adult tested for a GH deficiency

pituitary gland checked for response when it is stimulated to produce hGH

- decrease in hGH is confirmed

- patient injected with hGH