FEEDBACK MECHANISMS REGULATING FOOD INTAKE Flashcards
what is the function of feedback mechanisms?
help regulate food intake by acting upon the hypothalamus where centre’s for hunger and satiety reside
they work over short term to help regulate food intake
what is ghrelin?
is a peptide hormone mainly released by stomach and to lesser extent, small intestines
when is ghrenlin released?
during fasting state
what does ghrenlin signal?
acts on hypothalamus to signal HUNGER
when are ghrenlin levels reduced?
in people with obesity
what has an effect on adipocytes where is promotes storage?
ghrenlin
what is ghrenlin responsible for promoting?
orexigenic effects
why does distension of the stomach occur?
presence of food during a meal will activate STRETCH RECEPTORS - sending afferent signals to hypothalamus by ‘vagus nerve’ - helping to signal fullness and promote satiety
what is leptin?
means ‘thin’ - is a peptide hormone mainly released by adipocytes in direct proportion to their adiposity
leptin acts on receptors in the hypothalamus to inhibit what?
appetite and food intake - while increasing metabolic rate of the body
when are leptin levels increased?
in obesity - pattern of overfeeding contributes to leptin resistance
what is hunger?
sensory perception of an empty feeling that promotes food seeking behaviour
what is appetite?
is a personal desire for a particular type of food
what is satiety?
feeling of fullness or decreased desire for food
what is glucagon (GLP-1)?
like peptide 1, is released by distal ilium and colon when carbs are present
GLP-1 acts upon the hypothalamus to promote what?
satiety
what cells does glucagon stimulate?
beta cells of pancreas to release insulin
what is CCK (cholecystokinin)?
is a peptide hormone
when is CCK released?
released by enteroendocrine cells in response to the presence of fats in the duodenum
CCK acts upon hypothalamus where it promotes what?
satiety
what is insulin?
peptide hormone
when is insulin released?
released by pancreatic beta cells in response to post prandial elevations in blood glucose levels and during a meal in response to gastric distension
what does insulin suppress?
hypothalamic feeding signals in hypothalamus, reducing food intake
do feedback mechanisms signal the hypothalamus right away that you are ‘full’?
NO - takes time
what is the main function of parasympathetic stimulation?
inhibits feeding
