Regulation of Food Intake Flashcards
What are the functions of ghrelin? (5)
- increases appetite
- increases gastric motility
- increases gastric acid secretion
- increases adipogenesis
- both increases/decreases insulin secretion
INITIATES THE FEEDING RESPONSE!
Where is ghrelin secreted from? (4)
The endocrine cells into the stomach, hypothalamus, large and small intestines
What does ghrelin stimulate?
Neurons that release neuropeptide Y (NPY)
What are the functions of insulin? (2)
- decreases appetite
- increases metabolism
Where does insulin bind in the brain?
To receptors in POMC and NPY systems
- inhibits NPY path
- stimulates POMC path
Where is CCK released from?
I cells in duodenum
What does CCK do? (2)
- acts on vagal→NTS→ hypothalamus circuit to decrease ghrelin
- decreases gastric emptying
Overall ELICITS SATIETY!
Where is PYY released from?
L cells of ileum and colon
What does PYY do? (2)
Binds to Y2R in hypothalamus, thus:
- inhibiting NPY neurons
- releasing inhibition of POMC
Where is leptin secreted from?
adipose tissue, endocrine cells of stomach
What does leptin do? (4)
- decreases appetite
- increases metabolism
- decreases ghrelin release
- stimulates POMC path, inhibits NPY path
OVERALL SUPPRESSES APPETITE
What is obesity in humans associated with, in regards to leptin?
High leptin levels, failure to respond to endogenous leptin
What does glucagon-like peptide-1 (GLP-1) do? (3)
- reduces food intake
- suppresses glucagon secretion
- delays gastric emptying
What do L cells secrete? (3)
PYY, GLP-1, oxyntomodulin
What does oxyntomodulin do?
It has an anorectic effect
What does pancreatic peptide do?
decreases food intake directly through Y4R in brainstem and hypothalamus
What does glucagon do? (2)
- reduces food intake
- increases blood glucose levels and insulin secretion
What does amylin do?
- Inhibits NPY release (anorectic effect)
Where is amylin stored/released?
Stored w/ insulin, released w/it too
How does the gut-brain axis change in patients with anorexia nervosa?
- Baseline and pulsatile secretion of leptin reduced (associated w/ reduced fat mass)
- increased levels of PYY
What is the function of the lateral hypothalamic area? (LHA)
the hunger center
- releases orexigenic peptides (MCH, orexins A and B)
What is the function of the ventromedial hypothalamic nucleus? (VMN)
the satiety center
What is the function of the dorsomedial hypothalamic nucleus?
important for food-entrained circadian rhythms
What happens in the arcuate nucleus? (general)
Most of the integration signaling regarding food intake/energy expenditure
