Regulation of food intake Flashcards
Describe the anorexigenic pathway
POMC releases alpha-MSH which binds to MCR-4 present in 2nd order neurons
Signals to decrease food intake
Describe the Orexigenic pathway
Hunger (ghrelin) stimulates the release of NPY
NPY binds to Y1R
AGRP is also release to antagonize MCR-4
What are some genetic causes of obesity?
Leptin or leptin receptor gene deficiency
MC4R mutation
Prader-Willi Syndrome
Proopiomelanocortin deficiency
What aspect of prader-willi syndrome leads to obesity?
Paradoxically elevated ghrelin
What happens in regard to satiety if vagal activity is blocked?
The amount of material in the stomach no longer influences meal size
What is the Lateral Hypothalamic area?
Hunger center
stimulated by ghrelin and inhibited by CCK and leptin
What is the Ventromedial hypothalamic nucleus?
Satiety center
Stimulated by leptin insluin and CCK
Inhibited. by NPY
What does the paraventricular nucleus do?
It recieves info from arcuate nucleus and relays it to the cerebral cortex and areas of the brainstem
What are the actions of ghrelin?
Increase appetite
Increase gastric motility
Increase gastric acid secretion
Increase adipogenesis
Decrease insulin secretion
What does insulin bind to and what are its actions?
Binds to receptors in POMC and NPY systems
inhibits NPY pathway
Stimualtes POMC pathway
Decreases appetite
Increases metabolism
In patients with T1DM what is the response to a decrease in insulin?
Increase in food intake
What are the actions of CCK?
Released by I cells in duodenum
Elicits satiety
Acts on vagal circuit and decreases ghrelin
Decreases gastric emptying and increases gastric distention
What are the actions of PYY?
Released by L cells of the ileum and colon after a meal
Binds to Y2R in teh hypothalamus
Inhibits NPY
Releases inhibition of POMC neurons
What does leptin do?
Decreases appetite
Increases metabolism
Decrease ghrelin release
Obesity in human is often associated with what?
High leptin levels and failure to respond to exogenous leptin
