Appetite And Hunger Flashcards
Theories of hunger
Keesey and Powley (1986) set point theory
Return the body to optimum level of bodily resources
Hunger is a result of an energy deficit.
Each individual has an optimum level of energy resources which is their set point, homeostasis is returning to at set point.
Energy level - hunger - meal initiated
Hunger is evolutionary unlikely because…
1) need a system that can predict not just respond
2) need to cope with inconsistent resources in environment
Evolutionary unlikely …
Not supported
Reduction in blood glucose needed to start a meal is substantial and drinking a high calorie drink prior to meal does not stop the meal.
Lowe (1993) beliefs about the content of the drink has more of an effect
Ignores the environment
Theories of hunger
1) anticipation
Animals are driven to eat by the expected pleasure of eating
Expected pleasure = positive incentive reward
Theories of hunger
2) craving
Eating and the perception of hunger are initiated by craving, enables you to take advantage of good food when it is available
Theories of hunger
Multiple factors:
Flavour of the food Knowledge about food Time since last meal Blood glucose levels Amount of food in gut
Learned tastes, sclafani (1990) Dwyer, Haselgrove and Jones (2011)
Flavour A - glucose
Flavour B - nothing
Rats prefer flavour A
flavour A - LiCl
Flavour B - nothing
Rats avoid flavour A
Galef (1995) food preferences can be…
Socially acquired
Learning to eat vitamins and minerals
Fudim (1978)
Associating salt with flavours
Almond and salt. Banana and sugar.
Nothing - prefer banana and sugar
Injection of formalin to induce a salt need - prefer almond and salt
You can learn tastes of what you need
Learning to eat vitamins and minerals
Harris (1933)
Thiamine depleted rats learned to choose a complete diet and avoid a thiamine depleted diet
However this effect was weakened when there was a choice between 10 different diets
When do we eat ?
Collier (1986)
Many mammals eat many small meals throughout the day
Initiating a meal;
Woods (1991) pre meal hunger
Eating stresses the body and moves it away from homeostasis
Signals for a meal evokes a cephalic phase where you eat a meal under certain circumstances
Hunger is the body preparing for homeostasis disruption
Initiating a meal
Weingarten (1983)
Conditioned hunger in rats
Buzzer+light = food
Are more when buzzer and light was presented
Digestion process;
1) chewing. Mix with saliva
2) saliva lubricates food. This begins digestion
3) swallowing - asophagus to stomach
4) HCl breaks food down. Popsin - protein = amino acids
5) stomach empties via pyloric sphirictor to duodenum - intestine where absorption takes place
6) digestive enzymes - proteins - amino acid
Starch - sugars
Bloodstream - liver
7) fats broken by bile and carried by duodenum into the lympathetic system
8) absorbed into large intestine or ejected via anus
The ventral medial hypothalamus is the …
Satiety centre
Hetherington and Ranson (1940) lesions to the ventramedial lead to hyperphagia (overeating and obesity)
