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Biological explanations of eating behaviour
Description
Mindmap for AQA-A psychology unit 3 Biological explanations of eating behaviour
No tags specified
psychology
unit 3
aqa
a
a2
eating behaviour
biological
explanation
psychology
eating behaviour
undergraduate degree
Mind Map by
Brendan Williams
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Brendan Williams
over 10 years ago
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Brendan Williams
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Resource summary
Biological explanations of eating behaviour
Neural mechanisms
Homeostasis
Eating
Increase BGL
VMH activated
Satiety
Eating stops
Decrease BGL
LH activated
Hunger
Hetherington & Ranson - VMH lesions made rats over eat
Han & Lin - lesioned VMH then force fed rats. Lesion didn't cause overeating higher set point already reached
Anand & Brobeck - LH lesions stopped eating behaviour
Neither killed rats, must have been stopped somehow - dual control theory
LH lesions lower set point VMH lesions raise it - set point theory
Powley & Keesey - starved rats and lesioned LH. Lesion didn't stop eating, lower point already reached
Insulin & Glucagon maintain BSL. Bloodstream fat -> adipose tissue
Role of the hypothalamus
PYY - screted after meals, suggests fullness
Ghrelin - secreted by stomach, suggests hunger
Also activates NPY neurones
Marie et al - manipulated mice so NPY neurones not created, no change in feeding behaviour
Leptin levels increase when plenty of adipose
Insulin & Leptin reduced, NPY neurones stimulate orexigenic neurones
LH stimulated - starting eating
Insulin & Leptin increased, POMC neurones stimulate anorexigenic neurones
VMH stimulated - eating stops
NPY produced by abdominal fat. Vicious cycle where NPY causes more eating, producing more fat cells
Individuals at risk of increased NPY treated to prevent obesity
Gold - VMH lesions only produced overeating when including PVN
Findings not replicated in humans
In animals PVN lesion lead to increased feeding. In humans PVN detects food we need, may cause cravings
Neural control
Amygdala used to select food based on experience
Rolls & Rolls - surgically removed rats amygdala, they ate novel and familiar foods, unlike normal rats
Can explain the behaviour of Klüver–Bucy suffers who have an eat anything attitude, including non food items. Food cues no longer represent reward
Inferior frontal cortex recieves messages from the olfactory bulb
Kolb & Wishaw - damage caused decreased eating due to less sensory information affecting taste
Evolutionary explanations of food preference
EEA - the environment where a species first evolved
Adaptations to environment shaped food preferences
Humans lived in hunter gather society with preference for easy high calorie food
Men: Hunters. Women: childcare and foraging
Low cholesterol preference not from EEA. No advantages
Stanford - Chimps (mostly starved) go for the fattiest part of meat
Abrams - All human societies show preference for animal fat. Universal adaptation
Taste preference
Meat - packed with nutrients - catalyst for brain growth. Supplied AA and minerals
Adapted for meat - larger than average duodenum, for protein breakdown
Fatty foods - provided energy for survival
Distaste for sour - associated with gone off food - source of bacteria
Taste aversion - evolutionary advantage
Garcia et al - rats made ill by radiation after eating Saccharin (sweetener). Aversion developed from association
Eating poison and being sick makes you unlikely to eat the same food in the future. Hard to shift
Neese & Williams - Children's taste aversion to broccoli & brussels sprouts understood as they contain chemicals toxic to children
The medicine effect - preference developed for food eaten just before overcoming illness
Assocaited with feeling better
Food neophobia - evolutionary tendency to avoid new foods
Frost - Greater liking for familiar foods
Bernstein & Webster - chemotherapy patients given novel ice cream before treatment. Aversion developed
Hospitals now give patients novel and familiar foods
Cooking
Wrangham et al - food cooking started 500,000 years ago. Good way to kill bacteria
Lucas et al - cooking made food easier to chew, molar size decreased
Embryo protection hypothesis - morning sickness occurs in early stage of pregnancy during organ development
Buss - Coffee, tea, meat & eggs most avoided
Most common sources of bacteria
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