Control of appetite

Question 1

Appetite is controlled by the ……… in the hypothalamus

Answer 1

in the arcuate centre

Question 2

where is the arcuate centre found

Answer 2

the hypothalamus

Question 3

there is also a satiety centre which controls

Answer 3

the amount of food intake and timing of food intake

Question 4

The arcuate centre contains …………………………….., that sense metabolite and hormone levels.

Answer 4

primary neurones

Question 5

secondary neurones in other area of the hypothalamus receive

Answer 5

inputs from these arcuate primary neurones, and co-ordinate an appropriate response via the vagus nerve

Question 6

The primary neurones in the arcuate nucleus can be sub-divided into

Answer 6

excitatory primary neurones and inhibitory primary neurones.

Question 7

Excitatory neurones:

Answer 7

stimulate appetite via the release of neuropeptide-Y and agouti-related peptide.

Question 8

Inhibitory neurones:

Answer 8

supress appetite via the release of POMC (pro-opiomelanocortin).

Question 9

POMC

Answer 9

is a polypeptide prohormone, which can be cleaved to produce several peptide hormones (β-endorphin, ACTH, α-MSH).

Question 10

α-MSH acts on

Answer 10

melanocortin-4 receptors in order to induce appetite suppression.

Question 11

β-endorphins

Answer 11

create the reward system in the brain which produces feelings of euphoria and tiredness in response to eating.

Question 12

Stimulating Appetite

Answer 12

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.

Question 13

once we eat (in response to the increased appetite)

Answer 13

Once we eat (in response to the increased appetite), stretch of the stomach wall caused by the food intake inhibits ghrelin release.

Question 14

which hormones supress appetie

Answer 14

PYY
Leptin
Insulin
Amylin

Question 15

PYY

Answer 15

is released from the wall of the small intestine in response to digestion, and acts in opposition to ghrelin to suppress appetite.

Question 16

leptin

Answer 16

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

Question 17

insulin

Answer 17

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.

Question 18

neurones in the arcuate nucleus are also

Answer 18

able to sense the level of glucose and fatty acids in the blood

Question 19

which other hormone suppresses appetite

Answer 19

amylin

Question 20

amylin

Answer 20

• Peptide hormone also secreted by B cells in pancreas

- Decrease glucagon secretion and slows gastric emptying

Question 21

Pramlintide

Answer 21

is an amylin analogue approved for treatment of type 2 diabetes

Question 22

only stimulatory hormone

Answer 22

ghrelin