Appetite

Question 1

What is the appetite control centre called and where is it located?

Answer 1

Satiety centre in the accurate nucleus of the hypothalamus

Question 2

What are the two types of primary neurone found in the arcuate nucleus?

Answer 2

-stimulators neurones:
Containing Neuropeptide Y (NPY) and Agouti-related peptide (AgRP)
These promote hunger

-inhibitory neurones :
Containing pro-opiomelanocortin (POMC) [which yields several neurotransmitters including alpha-MSH and Beta-endorphin]
These all promote satiety (make you feel full)

Question 3

What are the two hormones produced from the gut that feed back to the hypothalamus?

Answer 3

Ghrelin: released from stomach wall when empty
*filling the stomach inhibits ghrelin release

PYY (peptide tyrosine tyrosine): released by ileum and colon in response to eating

Question 4

What effect does ghrelin have on the arcuate nucleus of the hypothalamus?

Answer 4

Stimulates the excitatory primary neurones (containing NPY and AgRP) and therefore stimulates appetite

Question 5

What effect does PYY have on the arcuate nucleus of the hypothalamus?

Answer 5

Inhibits the excitatory primary neurones (containing NPY and AgRP) and stimulates the inhibitory neurones (containing POMC). Therefore suppresses appetite

Question 6

What hormone is released by the adipocytes to suppress hunger?

Answer 6

Leptin: tell arcuate nucleus that the energy status is full

1. Stimulates the inhibitory (POMC) neurones
2. Inhibits the excitatory (AgRP/NPY) neurones

*Leptin induces expression of uncoupling proteins in mitochondria. Energy therefore dissipated as heat

Question 7

What effect does insulin have on appetite?

Answer 7

It suppresses it (like Leptin)

Question 8

Name another hormone secreted by the Beta cells of the pancreas that suppresses appetite, what other effects is it known to have?

Answer 8

Amylin

Also decreased glucagon secretion and slows gastric emptying

**pramlintide is an amylin analogue approved for treatment of type 2 diabetes- suppressive effects on appetite

Question 9

What hormones suppresses hunger?

Answer 9

PYY - inhibits primary stimulators neurone
Leptin - (same as above) and stimulates the primary inhibitory neurone
Insulin - stimulates primary inhibitory neurone

Question 10

What hormone stimulates hunger?

Answer 10

Ghrelin- stimulates the primary stimulators neurone