GI Phys- Regulation of Food Intake Flashcards
What activates the AGRP/NPY pathway?
Ghrelin activates the AGRP/NPY pathway in the arcuate nucleus of the hypothalamus which causes neuronal activation at the Paraventricular nucleus of the Hypothalamus.
*** This activates the body for FOOD INTAKE
What is the role of Insulin, Leptin, and CCK hormones on the AGRP/NPY pathway & POMCY/CART pathway?
Insulin, Leptin, CCK will ACTIVATE the POMC/CART pathway that causes the inhibition of food intake.
Insulin, Leptin, CCK will INHIBIT the AGRP/NPY pathway that causes inhibition of food intake as well (usually it would be stimulatory if activated)
What is the name for the pathway mediated by Insulin, Leptin, and CCK hormones?
Anorexigenic Pathway (inhibition of food intake via ACTIVATION of POMC/CART pathway & inhibition of AGRP/NPY Pathway)
What is the effect of activating the anorexigenic pathway?
This will cause you to DECREASE FOOD INTAKE & INCREASE METABOLISM
What is the pathway of the orexigenic pathway?
This will cause the INCREASE OF FOOD INTAKE & DECREASED METABOLISM
What is the function of Neuropeptide Y (NPY) pathway?
NPY pathway causes the activation of AGRP/NPY Pathway by binding to the Y1R receptor on the AGRYP/NPY nucleus of the arucate nucleus of the hypothalamus.
Pathways that activate the alpha-MSH pathway (POMC Pathway) inhibit the AGRP/NPY system.
Insulin, Leptin, CCK - binds to LepR Receptor
+ causes the activation of the pomc/cart pathway and
inhibition of the NPY/AGRP pathway by the release of
alpha-MSH.
- alpha-MSH inhibits MCR-3 receptors on the
AGRP/NPY Pathway
What happens when the vagal nerve activity is blocked?
The amount of material in the stomach no longer influences the meal size;
- increased meal size would lead to increased relaxation and secretion of acid from the parietal cells of the oxyntic glands.
How does the Feeding pathways and the vagal functioning interrelate?
Feeding patterns enter into the Nucleus Tractus Solitarus of the Hypothalamus (NTS) & and vagal afferents enter the nucleus tractus solitarus.
+ Signals are summated and released through the vagal efferents
Where are the different locations of the hormones secreted?
Leptin- fat cells
Ghrelin- from the walls of the stomach
CCK- liver
PYY- Large intestine (ascending)
What is the role of Ghrelin in the arcuate nucleus?
**(When you’re hungry!)
* Appears to initiate the FEEDING RESPONSE*
Secreted from endocrine cells of the stomach and Ghrelin goes through the blood and binds to the GHSR (Growth Hormone Secretagogue Receptors) on the NPY/AGRP neurons to stimulate FOOD INTAKE.
Vagal Efferent Actions: Increase Appetite, Increase
Gastric Motility, Increase Gastric
Secretions, increase adipogenesis,
decrease insulin secretion
Response of Insulin
Stimulate the POMC pathway and inhibit the NPY/AGRP pathway
Complications of Type I diabetes: Too much food that was taken in by the patient because there are barely any beta cells causing decreased insulin secretions
* ***the body thinks that its STARVING
* *** THESE PATIENTS OVEREAT
Special Consideration of the PYY peptide released by the small intestine and the colon?
PYY causes the de-inhibition of the POMC/CART Pathway and the inhibition of the AGRP/NPY pathway
What is the role of Leptin in the control of feeding behavior?
Leptin inhibits the AGRP/NPY pathway and activates the POMC Pathway.
Leptin Effects:
Decrease appetite, Increase Metabolism, decresae
Ghrelin Release from endocrine cells of the stomach
Is there a problem with TOO MUCH LEPTIN and obesity?
Yes; Leptin is good at decreasing appetite and increasing metabolism. The problem is that when there is TOO MUCH LEPTIN, what happens is that there is a DESENSITIZATION of the EFFECT OF LEPTIN.
***** This desensitization of leptin causes little to no effect of leptin on inhibiting the AGRP/NPY & activating the POMC Pathway.
