Pituitary Hormones Flashcards
Growth hormone is also known as what?
somatotropin (do NOT confuse with somatostatin)
Growth hormone is a ______ polypeptide.
single chain
There is a growth spurt of what hormone at puberty?
growth hormone
What hormone decreases with age?
growth hormone
Growth hormone secretion is what pattern?
pulsatile
What are the stimulators of growth hormone?
- Growth hormone releasing hormone
- decreased glucose
- decreased free fatty acids
- increased amino acids
- hypoglycemia/fasting/starvation
- puberty (estrogen/testosterone)
What factors are included in the nutrient regulation of growth hormone?
- decreased glucose
- decreased free fatty acids
- increased amino acids
What are the inhibitors of growth hormone?
- somatostatin
- increased glucose, free fatty acids
- growth hormone
- obesity
- somatomedins (Insulin like growth factors)
What are somatomedins?
produced by liver, stimulate somatostatin release from hypothalamus, inhibit it at anterior pituitary, includes insulin like growth factors
Growth hormone has metabolic actions on what structures?
- liver
- muscle
- adipose
- bone
Growth hormone affects what?
- linear growth
- protein synthesis
- organ growth
- carbohydrate and lipid metabolism
What are the direct anabolic actions of growth hormone?
increased Ca absorption from gut, P reabsorption from kidney, protein synthesis in liver
Growth hormone has indirect metabolic actions via?
somatomedins
What somatomedins cause the indirect actions of growth hormone?
IGF-1 (somatomedin C)
IGF-2 (somatomedin A)
What are the indirect anabolic actions of growth hormone?
increased lean muscle mass, linear bone growth, organ size/function
What are the direct catabolic effects of growth hormone?
- increased gluconeogensis in liver
- increased lipolysis in adipose tissue
Increased gluconeogensis in liver by growth hormone causes what?
decreases glucose uptake in muscle which leads to temporary insulin resistance (maintenance of blood glucose)
When free fatty acids are released into blood they bind what protein to become non-esterified fatty acids?
albumin
A deficiency of growth hormone leads to what condition?
dwarfism
Excessive growth hormone secretion leads to what condition?
acromegaly
What hormones are released from the posterior pituitary?
- antidiuretic hormone
- oxytocin
Which posterior pituitary hormone is synthesized primarily by neurons in supraoptic nuclei of hypothalamus?
antidiuretic hormone
Which posterior pituitary hormone is synthesized primarily by neurons in paraventricular nuclei of hypothalamus?
oxytocin
What is the peptide precursor of ADH?
prepropressophysin
What is the peptide precursor of oxytocin?
prepro-oxyphysin
When oxytocin is secreted due to stimulation by suckling, what results?
milk let down
When oxytocin in secreted due to stimulation of cervix by fetus, what results?
uterine contractions
What sensory receptors are responsible for suckling stimulation?
sensory receptors on myoepithlial cells of alveoli in mammary gland
Oxytocin acts on what muscle in the uterus?
smooth muscle
Oxytocin acts on what male reproductive structures to aid in sperm movement and ejaculation?
- testes
- epididymis
- prostate
What are the stimulators of ADH secretion?
- increased plasma osmolarity
- decreased blood volume (hypovolemia)
- decreased blood pressure
- pain
- nausea/vomiting
- hypoglycemia
- nicotine, opiates
What are the inhibitors of ADH secretion?
- decreased plasma osmolarity
- increased blood volume (hypervolemia)
- increased blood pressure
- ethanol
- glucocorticoids
The secretion of ADH leads to the reabsorption of what?
water
The inhibition of ADH means water is not reabsorbed, so it is excreted how?
excreted in urine
Water is reabsorbed where in the nephron under the influence of AHD?
- distal convuluted tubule
- collecting duct
What are the two major actions of ADH?
- free water absorption in the kidney
- vascular smooth muscle contraction
Vascular smooth muscle contraction caused by ADH is done by what receptor?
V1 receptor
Free water absorption by the kidney caused by ADH is done by what receptor?
V2 receptor
How does ADH cause free water absorption in kidney?
increase water permeability of principal cells in distal convoluted tubules and collecting ducts of kidney by inserting aquaporin 2 into membrane of principal cells
How does ADH cause vascular smooth muscle contraction?
constricts arterioles
Abnormal ADH secretion can cause what two conditions?
- diabetes insipidus (lack of ADH if central, cells unresponsive to ADH if peripheral or nephrogenic)
- syndrome of inappropriate ADH secretion (excess ADH)
