Control of appetite Flashcards
Appetite is controlled by the ……… in the hypothalamus
in the arcuate centre
where is the arcuate centre found
the hypothalamus
there is also a satiety centre which controls
the amount of food intake and timing of food intake
The arcuate centre contains …………………………….., that sense metabolite and hormone levels.
primary neurones
secondary neurones in other area of the hypothalamus receive
inputs from these arcuate primary neurones, and co-ordinate an appropriate response via the vagus nerve
The primary neurones in the arcuate nucleus can be sub-divided into
excitatory primary neurones and inhibitory primary neurones.
Excitatory neurones:
stimulate appetite via the release of neuropeptide-Y and agouti-related peptide.
Inhibitory neurones:
supress appetite via the release of POMC (pro-opiomelanocortin).
POMC
is a polypeptide prohormone, which can be cleaved to produce several peptide hormones (β-endorphin, ACTH, α-MSH).
α-MSH acts on
melanocortin-4 receptors in order to induce appetite suppression.
β-endorphins
create the reward system in the brain which produces feelings of euphoria and tiredness in response to eating.
Stimulating Appetite
When our stomach is empty, ghrelin (a peptide hormone) is released from the stomach wall, which activates the stimulatory neurones in the arcuate nucleus, which in turn stimulate appetite.
once we eat (in response to the increased appetite)
Once we eat (in response to the increased appetite), stretch of the stomach wall caused by the food intake inhibits ghrelin release.
which hormones supress appetie
PYY
Leptin
Insulin
Amylin
PYY
is released from the wall of the small intestine in response to digestion, and acts in opposition to ghrelin to suppress appetite.
leptin
is released into the blood by adipocytes (the level of leptin in the blood correlates with the amount of adipose tissue in the body). Leptin acts by stimulating inhibitory hormones and inhibiting stimulatory neurones in the arcuate nucleus to suppress appetite. This is an example of a feedback mechanism from the body’s fat stores in order to control food intake
insulin
can supress appetite via the same mechanism as leptin, but leptin is more important in this role. Insulin resistance is associated with obesity, and often leads to type 2 diabetes.
neurones in the arcuate nucleus are also
able to sense the level of glucose and fatty acids in the blood
which other hormone suppresses appetite
amylin
amylin
- Peptide hormone also secreted by B cells in pancreas
- Decrease glucagon secretion and slows gastric emptying
Pramlintide
is an amylin analogue approved for treatment of type 2 diabetes
only stimulatory hormone
ghrelin
