Eating Behaviour - Biological Explanations Flashcards
Evolutionary explanations of eating behaviour?
Evolution of food preferences in the EEA
Neural mechanisms involved in eating behaviour?
Homeostasis, lateral hypothalamus, ventromedial hypothalamus, neurotransmitters, drugs, neural control of cognitive factors
What is homeostasis?
Act of detecting the state of the internal environment and correcting the situation to restore it to it’s optimum state
Role of the lateral hypothalamus?
Hunger centre which turns on eating
LH is activated by?
Decrease of glucose and increase of ghrelin
What is ghrelin?
Hormone produced in the stomachs lining
Damage to the LH in rats caused…
Aphagia (absence of eating)
Role of the VMH?
Satiety centre for turning off eating
Turns on eating?
LH
Turns off eating?
VMH
VMH is activated by?
Rise of glucose and leptin, decrease of ghrelin and CCK release
What is leptin?
LT satiety signal by fat cells
Damage to the VMH in rats caused…
Hyperphagia (excess of eating)
Gold?
Damage to the VMH tends to damage the para ventricular nucleus
Neurotransmitters involved in eating?
Neuropeptide Y (NPY)
Noradrenaline (NE)
Serotonin
Role of NPY?
Turns on eating
NPY is found in…
The hypothalamus
Wilkens?
NPY can cause rats to immediately begin feeding, even when satiated
Research on NPY?
Wilkens
Role of NE?
Stimulates feeding when injected into the PVN, but reduces feeding when injected into the perfornical area
Role of serotonin?
Activated muscles in gastrointestinal tract used for feeding and causes decrease in food intake
Drugs influencing eating?
Nicotine, amphetamines and marijuana
Role of amygdala in eating?
Selection of foods on the basis of past experience
Research on amygdala?
Rolls and rolls
Rolls and rolls?
Amygdala-intact rats would initially avoid novel foods and consume familiar ones, but those with surgically removed amygdalas would consume familiar and novel foods indiscriminately
Strengths of explanations of neural mechanisms?
Real life applications
Weaknesses of neural explanations of eating behaviour?
Reductionist
Animal studies
Contradicting evidence
Real life applications of neural explanation of eating?
Yang et al
Yang et al?
Vicious cycle where NPY produced in the brain leads to more eating and production of more fat cells, which produce more NPY - we must target those at risk and turn it off
Reductionism in the neural explanation of eating?
For hunger mechanisms to be adaptive they must both anticipate and prevent energy deficits, not just react
Animal studies in the neural explanation of eating?
Tenuous and difficult to extrapolate
Contradicting evidence for neural explanation of eating?
Marie et al
Marie et al?
Mice genetically engineered so they didn’t produce NPY shower no subsequent decrease in eating behaviour
Where was the EEA?
2 million years ago on the African savannah
Obesogenic environment?
Factors in our environment now support being obese - our food focus has changed as it is no longer about eating enough to avoid malnutrition
Research on sweet foods?
Harris
Harris?
Babies like sweet tastes from birth
Why do we like sweet foods?
Rich in carbohydrates and energy, our ancestors were frugivores
Why do we like salty foods?
To replace salts lost through sweating on the savannah as they’re critical to cell functioning
Research on salty foods?
Denton
Denton?
Innate preferences for salty foods in animals
Why do we like umami?
Receding forests forced hunting, catalyst for brain growth
Research on umami foods?
Milton
Milton?
Humans would’ve never evolved to be an active, intelligent species without meat
Why do we not like sour foods?
May’ve gone off
Why don’t we like bitter foods?
May be poisonous
Why do we like fatty foods?
High levels of energy needed in the EEA
Research on fatty foods?
Burnham and Phelan
Burnham and Phelan?
Preference for fatty foods comes from times of food scarcity where we needed calories
Evolved tastes in early diets?
Sweet Salty Umami Sour and bitter Fatty
Research on taste aversion?
Garcia et al
Garcia et al?
Rats made ill through radiation after eating saccharin developed an aversion to it
Research on the medicine effect?
Garcia et al
Garcia et al? (Medicine effect)
When a distinctive flavour was presented to a thiamine deficient rat before an injection of thiamine, they acquired a preference for that flavour
Strengths of evolutionary explanations for eating?
Real life applications
Weaknesses of evolutionary explanations for eating?
Reductionist
Unfalsifiable
Ignores cultural influence
Real life applications of evolutionary explanations for eating?
Scapegoat technique in chemo - Bernstein and Webster
Bernstein and webster?
Gave patients a novel tasting ice cream prior to chemo and they acquired an aversion to it
Reductionism in evolutionary explanations for eating?
Search for ultimate causes may mask proximate ones
Unfalsifiablity in evolutionary explanations for eating?
Cordain et al v Abrams
Cordain et al?
Ancestors could’ve been healthy eaters or vegetarians as they consumed most calories from sources other than animals
Abrams?
Wouldn’t have been possible for ancestors to be vegetarians as they wouldn’t get sufficient calories
Ignorance of cultural differences in evolutionary explanations for eating?
Evolved factors are modified by experiences determined by culture, eg spicy foods
