Regulation of Food Intake

Question 1

where are the neuronal centers that control feeding and satiety located?

Answer 1

within the hypothalamus

Question 2

how does the hypothalamus receive signals from the GI tract?

Answer 2

via the vagus nerve

Question 3

where does most of the integration signaling regulating food intake and energy expenditure happen?

Answer 3

in the arcuate nucleus

Question 4

what neurons are involved in the anorexigenic pathway?

Answer 4

pro-opiomelanocortin (POMC) neurons or CART

Question 5

what stimulates the POMC/CART neurons?

Answer 5

insulin, leptin, and CCK

Question 6

what happens when insulin, leptin, or CCK stimulate the POMC/CART neurons?

Answer 6

they will release alpha-MSH

Question 7

where does the alpha-MSH bind to in the anorexigenic pathway?

Answer 7

on their receptors- MCR-4 on the second order neurons in the paraventricular nucleus

Question 8

what is the result of alpha-MSH binding to the MCR-4 receptors

Answer 8

decreased food intake and an increase in energy expenditure

Question 9

what neurons are involved in the orexigenic pathway?

Answer 9

AGRP and NPY

Question 10

what stimulates the AGRP and NPY neurons?

Answer 10

Ghrelin

Question 11

what inhibits the AGRP and NPY neurons?

Answer 11

insulin, leptin, and CCK

Question 12

what does NPY bind to?

Answer 12

its receptor- Y1R on the second order neuron in the PVN

Question 13

what is AGRP an antagonist of?

Answer 13

MCR-4

Question 14

what happens when NPY binds to its Y1R receptor on the second order neuron in the PVN?

Answer 14

it will result in an increase in food intake

Question 15

what have some cases of obesity been related to?

Answer 15

mutations in the POMC and MCR-4 genes

Question 16

what is the finding with prader-willi syndrome?

Answer 16

partial deletion of chromosome 15

Question 17

what are the symptoms of prader willi syndrome?

Answer 17

small hands and feet, hyperphagia, and paradoxically elevated ghrelin

Question 18

several peptides that stimulate satiety and decrease feeding activate what?

Answer 18

receptors on vagal afferents

Question 19

where do the vagal afferents travel?

Answer 19

to the nucleus tractus solitarius and then to the hypothalamus

Question 20

what kind of information do the vagal afferents carry?

Answer 20

gastric distention, levels of gut hormone, type of lumenal content

Question 21

what is considered to be the hunger center?

Answer 21

the lateral hypothalamic areas (LHA)

Question 22

what is considered to be the satiety center?

Answer 22

the ventromedial hypothalamic nucleus

Question 23

what is ghrelin secreted by?

Answer 23

endocrine cell in the stomach

Question 24

what does ghrelin stimulate?

Answer 24

neurons that release NPY

Question 25

what is the only known orexogenic gut hormone?

Answer 25

ghrelin

Question 26

what is ghrelin release associated with?

Answer 26

increased appetite- it appears to initiate the feeding response

Question 27

where does insulin bind?

Answer 27

to receptors in the POMC and NPY systems

Question 28

what happens when insulin binds to the POMC system?

Answer 28

it is going to stimulate it

Question 29

what happens when insulin binds to the NPY system?

Answer 29

it is going to inhibit it

Question 30

what is the action of insulin?

Answer 30

it is going to decrease appetite and increase metabolism

Question 31

what is CCK released by?

Answer 31

I cells in the duodenum

Question 32

what does release of CCK do?

Answer 32

elicits satiety

Question 33

what is the mechanism of CCK release?

Answer 33

it is going to act on the vagus nerve, which then travels to the NTS, and then to the hypothalamus circuit

Question 34

what are the actions of CCK?

Answer 34

it is going to cause an inhibition of the release of ghrelin; it is also going to increase gastric distention and therefore decrease gastric emptying

Question 35

what is PYY release by?

Answer 35

L cells of the ileum and the colon following a meal

Question 36

what does PYY bind to?

Answer 36

Y2R in the hypothalamus

Question 37

what is the action of PYY?

Answer 37

it is going to inhibit NPY neurons and it is going to release the inhibition of POMC neurons (so it promotes the anorexigenic pathway)

Question 38

what is leptin secreted by?

Answer 38

cells in adipose tissue

Question 39

what does leptin bind to?

Answer 39

receptors in POMC and NPY systems

Question 40

what happens when leptin binds to the NPY pathway?

Answer 40

it is going to inhibit it

Question 41

what happens when leptin binds to the POMC pathway?

Answer 41

it is going to stimulate the POMC pathway

Question 42

what are the actions of leptin?

Answer 42

it is an appetite-supressing hormone; it causes decreased appetite, increased metabolism, and decreased ghrelin release

Question 43

obesity in humans is often associated with what type of levels of leptin?

Answer 43

high leptin levels and failure to respond to exogenous leptin (leptin resistance)

Question 44

What type of regulation is adiposity signals (leptin) involved in?

Answer 44

long-term regulation of energy balance

Question 45

what is glucagon-like peptide co-secreted with?

Answer 45

PYY from L cells in the intestin

Question 46

when do the levels of glucagon-like peptide rise and fall?

Answer 46

levels rise after a meal and fall during fasting

Question 47

what are the actions of glucagon-like peptide?

Answer 47

reduce food intake, suppresses glucagon secretion, and delays gastric emptying

Question 48

where is oxyntomodulin released from?

Answer 48

released from L cells of the intestine in response to ingested food

Question 49

what is the effect of oxyntomodulin?

Answer 49

anorectic effect

Question 50

where is pancreatic peptide (PP) secreted from?

Answer 50

from cells in the pancreatic islets of Langerhans

Question 51

what is the action of pancreatic peptide?

Answer 51

it decreases food intake directly through Y4R in the brainstem and the hypothalamus; may also act via the vagus nerve to produce anorectic effects

Question 52

what is the action of glucagon?

Answer 52

increase blood glucose levels and insulin secretion and reduces food intake

Question 53

where is amylin stored and released from?

Answer 53

stored and released with insulin in response to food intake

Question 54

what is the effect of amylin?

Answer 54

anorectic effects (inhibition of NPY release)

Question 55

what is anorexia nervosa characterized by?

Answer 55

self-starvation and excessive weight loss

Question 56

what biological factors are related to anorexia nervosa?

Answer 56

polymorphisms in genes involved in eating attitudes; basal and pulsatile secretion of leptin is reduced; ghrelin resistance; elevated levels of PYY