Biological Explanations of Eating Behaviour Flashcards
Name the three biological explanations of eating behaviour.
- Evolutionary Explanations for Food Preferences
- Homeostasis
- Inferior frontal cortex (smell)
What is the basic background of evolutionary exolanations?
- Modern food preferences are leading to obesity, diabeties and heart disease.
- These preferences have remained hard-wired winto our genetic makeup as they were adaptive in an Enviroment of Evolutionary Adaption (EEA)
- It remains in our genetics even though it is nonger adaptive throught he process of gene-lag
- Therefore, our desire to eat certain unhealthy foods is beyond our conscious control.
What specific eating behaviours can enviromental explanations explain?
- Preference for High Fat - give energy and fat stores (for famime and insulation)
- Preference for Sweet foods - high energy (quick release)
- Preference for meat - muscle growth and bodily repair. Meat also developed our ancestors’ brains
What are some wider issues of enviromental explanations?
- Lacks scientific credability - cannot falsify, no empirical evidence and therefore.
- Genetic determinism - ignores free will, it is flawd, what about vegetarians/vegans who override their innate drives
- WHO predicts 2.3billion overweight people worldwide by 2015. Evolutionary views are unhelpfully deterministic suggesting people have little conscious control! However, we know that enviromental factors also play a part (media, mood, etc).
Outline neural mechanisms that control eating behaviour.
- Brain controls feeling of hunger and satiety as part of the process of homeostasis.
- Through homeostasis, the brain aims to maintain an equillibrium within the body by turning on and off feelings of hunger depending on blood glucose levels.
- Lateral hypothalamus acts as a ‘switch on’ for hunger whilst ventromedial hypothalamus acts as ‘switch off’. This is called dual cetre theory.
Outline the hunger/satiety feedback loop of dual centre theory.
- Eating
- Increase in lood lucose level
- Ventromedial Hypothalamus activated
- Feeling of satiety
- Eating stops
- Decrease in blood glucose level
- start eating again
Outline one pice fo research to support dual-centre theory.
Teitelbaum & Epstein:
- damage to the lateral hypothalamus cased aphagia (failure to eat) in ratsto the extent that they would starve themselves to dealth - supports dual-centre theory that LH is a ‘switch-on’ for hunger.
- damage to ventromedial hypothalamis cause hyperphagia (over-eating) in rats to the extent that they tripled their body weight in 3 months - supports dual cenrtre theory that VMH is ‘switch off’ for hunger
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What research suggests that dual-centre theory is not as straight forward as origionally thought?
- Neurotransmitters and not just areas of the brain need to be considered.
- Neuropeptide-Y (NPY) was injected into hypathalamus of rats and caused them to begin eating immediately even if they were full.
- Suggests that neuro mechanisms involved in controlling eating are more complex that dual-centre theory suggests.
What are the 2 implications of using rats in experiments?
- Lack of EXTERNAL VALIDITY because we cannot GENERALISE from animals to humans.
- ETHICAL ISSUES as there is widespread concerne about replacing humans with other animals.
Apart from low blood glucose levels, what else has been found to trigger a neuro mechanism causing feelings of hunger and how does it work?
- when we smell food!
- food smells triger the inferior frontal cortex which recieves messages via the olfactory bulb. which is responsible for our sense of smell.
- Inferior frontal cortex is responsible for our perception of how rewarding/enjoyable food is likely to be and the more active it is, the more likely we are to want to eat!
WHat are the two brain terms associated with smell?
Inferior frontal cortes which recieves massages via the olfactor bulb.
Inferior frontal cprtex affecting eating is supported by research from…? Explain..
Kolb who found that damage to the inferior frontal cortex led to a decrease in eating which supports the idea that there is a link between smell and pleasure.
What are some medical practical applications of understanding neural mechanisms to do with a desire to eat?
- medicalises eating behaviour and reduces stigma for people who are obease or have eating disorders by explaining feelings of hunger as a biological process and removing personal responsibility. Help people feel better.
- By understanding neuromechanisms effective anti-obesity treatments can be developed. (particularly in the case of NPY)
What is a wider issue to a purely bilogical approach to eating behaviour?
REDUCTIONIST:
- people may feel that there is nothing they can do to change their behaviour.
- Especially problematic for people whoes eating behaviour is a serious risk to health.
- Other social and cultural factors affect eating behabiour including media, early learning experiences and mood.
