Eating behaviour

Question 1

What can behaviour be?

Answer 1

1) Consious
- eg. writing lecture notes
2) Unconcious
eg. reflex movement from pain

Question 2

What is leptin?

Answer 2

A protein released by fat cells to:

• Decrease eating behaviour
• Increase energy expenditure
• Can be used to reverse obesity in mice

Question 3

What does high levels of leptin do?

Answer 3

• Activates receptors on neurons in the arcuate nucleus in the hypothalamus which contains the neurotransmitters alpha-MSH and CART

Question 4

What is catabolism?

Answer 4

The breaking down of macromolecules for energy usage

Question 5

What is the ‘hunger centre’ in the brain?

Answer 5

The lateral hypothalamus

Question 6

What happens if anabolism > catabolism?

Answer 6

Obesity

Question 7

What is the W/C model for motivation?

Answer 7

• Motivation is like water filling up the cistern
• Water filling up - increase in motivation
• Flushing releases behavior and motivation is low
• Gradually motivation builds up again until there needs to be another release

Question 8

How do some foods produce change in mood?

Answer 8

• Carbohydrates elevate serotonin levels

- During stress, typical to see carbohydrate-rich feeding

Question 9

What does decreasing levels of leptin cause?

Answer 9

1) Stimulates OTHER neurons in the arcutate nucleus which contain NPY (neuropeptide Y) and AgRP
2) Switches off the effects of alpha-MSH and CART

Question 10

What is motivation?

Answer 10

The driving force behind a behavior can be:
Simple - the need to urinate, eat or drink
Complex - need to sing and dance when happy

Question 11

Where do the activated neurons in the arcuate nucleus project to and cause what to happen?

Answer 11

1) Lower brain stem and upper spinal cord
- Activates them and increases sympathetic activity
- Causing increase in body temp and BMR

2) Paraventricular nucleus of the hypothalamus
- P nucleus projects to endocrine organs
- Stimulation of P nucleus causes release of TSH and ACTH
- Act on the thyroid and adrenal gland to increase BMR

3) Lateral hypothalamus
- Feeding behaviour inhibited by somatic motor activity

Question 12

What did bilateral lesions of a rat’s ventromedial hypothalamus cause?

Answer 12

Overeating and obesity

Question 13

What are the short-term factors which influence daily food intake?

Answer 13

• Cultural pressures
• Meal times
• When we last ate
• How much we last ate

Question 14

How are human behaviours complicated when it comes to motivation?

Answer 14

1) Probability and direction of a behaviour will vary with the driving force (motivation)
2) Motivation may not guarentee a behaviour (due to social, cultural influences)
3) Balance conflicting motivations (eg. go to a lecture or go and play cricket)

Question 15

What does NPY and AgRP do?

Answer 15

Released in respose to falling leptin levels:

1) Inhibit TSH and ACTH
2) Activate parasympathetic nervous system
3) Stimulate feeding behaviour

Question 16

What are ‘anoretic peptides’?

Answer 16

• Appetite supressors

- Injection of a-MSH and CART mimic the effect of raised leptin levels

Question 17

What do satiety signals do?

Answer 17

Terminate feeding and inhibit future feeding

Question 18

What did Coleman propose?

Answer 18

That a soluble factor in obese mice (from the ob gene) fooled the brain into thinking fat levels were normal - mouse continued to eat

Question 19

What does prozac do?

Answer 19

• Elavates serotonin levels and can relieve depression and bulimia
• Elevating serotonin levels can inhibit appetite

Question 20

In the process of eating, what is the motivation and what is the behaviour?

Answer 20

• Motivation is hunger

- Behaviour is eating

Question 21

What does gherelin do?

Answer 21

It is released into the blood stream from an empty stomach

• Stimulates NPY and AgRP release
• Stimulates feeding behaviour

Question 22

What is anabolism?

Answer 22

The building up of macromolecules for energy storage

Question 23

What to leptin happens during times of starvation and what does this cause?

Answer 23

Leptin deficiency:

• Stimulates eating behaviour
• Reduces energy expenditure
• Reduces reproductive competence

Question 24

What modifies the long-term regulation of feeding (leptins)?

Answer 24

• Short-term signals that are generated as we eat

- Satiety signals are produced during eating and initial digestion

Question 25

What is hedonistic motivation?

Answer 25

Enjoying food/eating

Question 26

What are examples of satiety signals?

Answer 26

• Distension of the stomach
• Cholecytokinin
• Insulin

Question 27

What are orexigenic peptides?

Answer 27

• Appetite stimulant

- NPY and AgRP

Question 28

What is behaviour?

Answer 28

The response of an organism to a stimulus

Question 29

Where is eating behaviour controlled?

Answer 29

The hypothalamus

Question 30

What did incision of both sides of a rat’s lateral hypothalamus cause?

Answer 30

Anorexia

Question 31

What did Kennedy propose?

Answer 31

Lipostatic hypothesis - the brain monitors and maintains fat levels
- Signal from the fat tissue to the brain hypothesised to tell the brain about fat levels

Question 32

How does the need for energy change?

Answer 32

Depending upon:

• Time of day
• Time of month
• Time of year
• Time of life
• Level of activity
• State of health

Question 33

What is the ‘satiety (fullness)’ centre in the brain?

Answer 33

The ventromedial hypothalamus

Question 34

What happens is catabolism > anabolism?

Answer 34

Starvation