Neural And Hormonal Mechanisms In The Control Of Eating Behavior

Question 1

The dual centre model of eating

Answer 1

Two structures in the hypothalamus provide homeostatic control

Question 2

Lateral hypothalamus

Answer 2

-feeding centre
-detects when glucose falls below a certain threshold in the liver
-Increases the release of neuropeptide Y
-This causes the individual to become hungry and triggers the motivation to eat along with behaviors like preparing food

Question 3

Ventromedial hypothalamus

Answer 3

-Satiety centre
-Once the glucose levels (stored glycogen) in the liver increase past a certain point it’s detected by the VMH
-This triggers VMH activity and inhibits the LH
-The individual feels full and stops eating

Question 4

Ghrelin

Answer 4

-More gremlin is released from the stomach, the emptier the stomach is
-When gremlin levels rise beyond a point, the arcuate nucleus signals to the lateral hypothalamus to secrete neuropeptide Y

Question 5

Leptin

Answer 5

-Leptin is a hormone released by adipose (fat cells)
-Leptin is an appetite suppressant that signals to the ventromedial hypothalamus when it reaches a certain point

Question 6

Research support for dual centre model

Answer 6

-Hetherington and Ranson
-The lesioning of rats VMH causes them to become hyperphagic (overeat) and become severely obese

-Anand and Brobeck
-lesioned the LH of rats and they became aphagic (stopped eating)

Question 7

Extra PEEL

Answer 7

-Animal studies, not generalisable

Question 8

Research support VMH

Answer 8

-Reeves and Plum
-Reported a case of a women’s weight doubling in two years
-A post mortem investigation revealed a tumor growing on her VMH causing her normal ‘stop eating’ functions to fail

Question 9

Practical application, Leptin

Answer 9

-Licinio
-Rare genetic condition where individuals are unable to produce leptin naturally, associated with severe obesity
-Leptin replacement therapy over an 18 month period led to an average weight loss of 40% and a reduction of food intake at 49%

Question 10

Oversimplified explanation

Answer 10

-Valassi
-A hormone called CCK is produced in the duodenum, it activated nerves which signal the gastrointestinal tract to signal the ventromedial hypothalamus
-CCK may be a more powerful appetite suppressant than leptin

-Other chemicals like serotonin and dopamine also contribute to the process of eating since they are used to inhibit or enhance other chemicals abilities