neural and hormonal mechanisms of eating

Question 1

why does homeostasis occur

Answer 1

this is to maintain a steady internal environment part of this is detecting whether the body has enough nutrients and correcting the situation is this not the case

Question 2

what is the dual centre model and what does it include

Answer 2

Within the hypothalamus are two significant eating control centres the central hypothalamus and ventromedial hypothalamus
these two parts of the hypothalamus work together to control food consumption and weight

Question 3

what is the lateral hypothalamus

Answer 3

the on switch for Hunger contain liver cells which detect glucose levels
when it detects a decline in blood glucose levels it will release npy which is an appetite stimulant which causes the feeling of Hunger
leading to the person eating which then leads to an increase in blood glucose levels

Question 4

what is the ventro medial hypothalamus

Answer 4

increasing glucose is detected by the liver cells which communicate with the vMH which is the satiety centre

which causes a feeling of satiety and instruct eating behaviour to stop eating
decreases blood glucose levels were decreased and the cycle repeats

Question 5

what is leptin

Answer 5

leptin insulin hormone which is released based on our fat levels
it’s release directly proportional to fat content produced by Fat cells and released into the bloodstream

Question 6

when does levels change

Answer 6

short-term fluctuation, leptin increAES when food is consumed and provides info to the vmh about the calorie intake

Question 7

how does leptin bind

Answer 7

when fat increases leptin increases and suppresses appetite causing vmh to trigger satiety
Leptin binds to receptors and pass on information this instruct the release of npy and triggers satiety

Question 8

what about leptin deficiency

Answer 8

if there is leptin deficiency there is less satiety it which leads to overeating which may cause obesity of the
if initialy born with leptin deficiency treated with leptin injection`

Question 9

what is ghrelin

Answer 9

is a hormone secreted by the stomach and stimulates the hypothalamus to increase appetite

Question 10

what do ghrelin levels show

Answer 10

it is a hormonal Mark of how long did we last have a meal

if a person is under eating their ghrelin levels increase

Question 11

what does the levels depend on when does it change

Answer 11

The ampunt produced produced is closely related to how empty your stomach is
The levels of ghrelin in the bloodstream doubles just before a meal and decreases very quickly after a meal

Question 12

how does ghrelin bind

Answer 12

receptors in the LH causes triggers of LH to release npy to increase the levels of hunger

Question 13

what is the research about the role of the hypothalumus having a role in eating behaviour

Answer 13

annand and brobeck
they found that damaging the lateral hypothalamus in rats lead to a loss of Interest include decrease eating and Weight loss

Question 14

what does this show

Answer 14

This shows that the lh is the hunger centre and it is the on switch for hunger
As when it was damaged they did not feel hungry and they lost weight

Question 15

what does ransome demonstrate

Answer 15

show damage to the ventromedial hypothalamus let the animals overeating and until they were grossly obese this proves that the vmh is needed for the satiety centre

Question 16

what does this shows

Answer 16

that the vmh is the satiety centre, as when this was damaged there was no feelings of satiety so the rats continued overeating as they didnt feel full, leading to obesity

Question 17

a weakness of research is that we cannot extrapolate animal eating, hormal and neural mechanisms to humans

Answer 17

Human behaviours eating behavoiours are much more complexed and are affected by other factors rather than soley leptin and ghrelin

Question 18

factors usch as what

Answer 18

It depends on whether we like and will enjoy the food,our dietry needs , and different factors however these factors have no affect on animals even though our lh is active and we are hungry we can resist the food

Question 19

so what

Answer 19

this means we cannot apply the theory from animals to humans as these factors dont affect animals therfore decreasing validity

Question 20

what is the research for the role of leptin

Answer 20

Research has shown some mice recieve two copies of the obesity gene
These ob ob mice have a tendency to overeat especially food that are high in fat or sugar
These ob ob mice have a defective gene which makes them deficient in the hormone leptin
Injecting mice with leptin makes them reduce weight drasticly

Question 21

why is this a strength

Answer 21

This shows hows leptin is needed for the feling of satiety as it is proportional to the fat content and how full we are
As when they had defieciency they never felt satiety so carried on eating
With the addition of leptin they became full and felt satiety

Question 22

there is research for the support of ghrelin

Answer 22

Wren et al provided support for the role of grhelin in a random double blind study of 9 healthy volunteers
They were given a drip of either saline or ghrelin and the other condition on the next week
Their apetitie was measured by how much they ate in a free food buffet

Question 23

what was the findings

Answer 23

there was a 28% difference between participants injected with saline and those injected with ghrelin

Question 24

what does this show

Answer 24

the This shows that ghrelin is an apetitie stimulant as when they where injected with ghrelin it stimulated the lh to release npy which stimulates hunger thus we saw an increase of food consumption in the buffet