Eating and appetite

Question 1

theories of hunger

Answer 1

• hunger consequence of energy deficit
• optimal level of energy - a set point
• homeostasis
• as energy drops, hunger increases = meal

Question 2

problems with theories of hunger

Answer 2

1. evolutionarily unlikely
   - cope with inconsistent resources
   - doesnt just respond to energy deficit
2. not supported by evidence
   - reduction in blood glucose substantial
   - high calorie drink doesnt stop meal
   - beliefs has more efficient

Question 3

positive incentive theory

Answer 3

anticipation
- animals driven by pleasure of eating
- expected pleasure = positive incentive value
craving
multiple factors
- flavour, knowledge, time, glucose

Question 4

learned taste preference

Answer 4

conditioned taste preference
flavour a > glucose preserved
flavour b > nothing
conditioned taste aversion
flavour a > LiCl > avoided
flavour b > nothing
can be socially acquired

Question 5

what do we eat

Answer 5

learning to eat vitamins
associating salt with flavours
almond + salt > nothing > banana
banana + salt > formalin > almond

Question 6

poor diet - Harris et al: thiamine depleted rats

Answer 6

chose complete diet
effect weakened when 10 choices

Question 7

when do we eat?

Answer 7

Coolier - small meals
1. pre meal hunger
- eating stressed body - not homeostatic
- evoke cephallic phase, insulin released
- body prepared for homeostatic disruption
2. conditioned hunger in rats
- buzzer + light > food

Question 8

physiological research

Answer 8

the hypothalamus
ventramedial - satienty centre VMH regions - hyperphagia

Question 9

VMH syndrome

Answer 9

1. dynamic phase - excessive eating, weight gain
2. static phase
   - body weight maintained, overweight after diet
   - lateral hypothalamus - feeding centre
   Anand and Brobeck - lesion = aphagia
   LH syndrome
3. aphagia accompanied by adipsia
4. recovery possible - spontaneous eating recovered
   BUT…
5. WMH lesions damage PVN - hyperphagia and obesity
6. regulate metabolism - not eating
   increase blood insulin
7. increase lipogenesis
8. decrease lipolysis
   rats consume more calories to meet demand
9. motor disturbances, lack of responsiveness

Question 10

the stomach

Answer 10

Cannon and Washburn
- contractions correlate with hunger
- patients without stomach, still hungry
Koopmans
- extra stomach and intestine in rats
- food injected decreased eating
- but no functioning nerves
- reached through blood flow

Gibbs, Young and Smith
CCK injected into rats, ate less
Leptin - genetic mutation in mice, low leptin ate more, covert to fat better negative feedback to lower appetite
:) treat obesity
:( don’t decrease eating or body fat