mancatul

Question 1

Why do we eat?

Answer 1

To supply the body with energy that we need to survive.

Food is enjoyable

To socialise - there is bonding when socialisation happens around food

Question 2

What are the 3 forms that energy is available in?

Answer 2

Immediate use (when we need fuel) -
1. glucose (simple sugar)

Short- and long-term reservoirs -
2. amino acids (broken down from proteins)
3. lipids (fats)

Question 3

What are the structures involved in the control of eating?

Answer 3

The gut-brain axis which links the brain and the digestive system

Question 4

What controls eating?

Answer 4

1. Chemical messengers
2. Neural and cognitive factors
3. Social and environmental factors

Question 5

What are the chemicals regulating hunger or satiety?

Answer 5

Hunger: ghrelin
Satiety: leptin, PYY, insulin

Question 6

What is the network of interacting brain regions that controls eating?

Answer 6

Cortex
Hypothalamus
Brainstem

Question 7

What is the role of the cortex in neural control of eating?

Answer 7

Cortex is involved in taste perception and food appreciation.

Question 8

What is the role of the orbitofrontal cortex (OFC, part of prefrontal cortex)?

Answer 8

It is linked to encoding of reward value of food

Question 9

What is the role of the hypothalamus in the neural control of eating?

Answer 9

The arcuate nucleus contains receptors of ghrelin, leptin, insulin and serotonin.

Question 10

What are the regions of the arcuate nucleus?

Answer 10

Lateral hypothalamic area LHA - hunger centre

Ventromedial nuclei VMN: satiety centre

Question 11

What is ghrelin?

Answer 11

A hormone secreted from the stomach when it is empty.
Signals hunger
High before meals
Decreased after meals

Also linked with some parts of the brain engaged in reward processing.

Question 12

What signals satiety? (stomach)

Answer 12

Stomach contains nutrient receptors.
An animal will keep eating if food does not get to the stomach.

Stomach detects nutrients not volume

Question 13

What signals satiety? (Intestine)

Answer 13

Intestine
1. CCK - a hormone secreted in part of the intestine and involved in breaking down fats
CCK release is triggered by food in the gut and this sends a satiety message to the brain (hypothalamus)

2. PYY - released after a meal, in proportion to the calories ingested

Question 14

What signals satiety? (liver and pancreas)

Answer 14

Liver and pancreas
Signals to the brain that food and nutrients have been digested

Also leptin is realised by fat tissue as satiety signal
More leptin - less appetite

Question 15

What happens if the lateral hypothalamus LH is lesioned?

Answer 15

If lesioned an animal will lose interest in food.
If stimulated an animal will be overeating.

Question 16

What happens if the ventromedial hypothalamus is lesioned?

Answer 16

If lesioned an animal will overeat.
If stimulated an animal will lose interest in food.

Question 17

What is an issue with saying that lateral hypothalamus is the centre of hunger?

Answer 17

If lesioned, eating recovers voluntary despite no recovery of the LHA.
This would not happen if hunger was the centre

If stimulated, besides overeating other behaviours happen (running). LH might be involved in arousal rather than eating.

Question 18

What is an issue with saying that ventromedial hypothalamus is the centre of satiety?

Answer 18

Lesions to the VMH alone do not cause overeating.
Overeating involves lesion to VMH and other areas.

Question 19

What is the set-point theory?

Answer 19

Individuals engage in eating behaviour to maintain internal homeostasis (a stable, constant internal state).

If energy levels are below target - we eat
If target is reached - we stop eating

Question 20

What is the system trying to maintain?

Answer 20

Glucose levels (glucostatic set-point theory): which may regulate day to day eating

Body fat levels (lipostatic set-point theory): which may regulate long-term weight

Question 21

What is evidence to support set-point theory?

Answer 21

Glucoprivation and lipoprivation can be experimentally induced and will stimulate eating up to when the set-point is reached, supporting set-point theory.

Question 22

What is evidence against set-point theory?

Answer 22

We eat even when glucose levels are high
In everyday life drops in glucose and fat levels are not enough to induce eating

Question 23

What is eating as conditioning?

Answer 23

Just seeing food can make us hungry.

Question 24

What is eating as habituation?

Answer 24

When we eat the same food for a long time, being presented with another option is tempting.

Question 25

What is sensory specific satiety?

Answer 25

Satiety is specific to the taste of food recently digested – we get full faster if meals are limited to one food type

Variety of food increases meal size

Question 26

What are the advantages and disadvantages of eating as habituation?

Answer 26

Advantages:
-encouraged to have variety in our diet
-reduces the possible accumulation of toxin that may be in a food

Disadvantages:
-may contribute to weight increase

Question 27

What are the negative effects of eating with others?

Answer 27

Increased meal size in social situations.
Researchers found a positive relationship between amount of food eaten and number of people present.

Question 28

What are the positive effects of eating with others?

Answer 28

Sharing food promotes cooperative skills.
Those who shared plates showed greater cooperation.