2/ Eating behaviours - Neural and hormonal mechanisms in the control of eating behaviour Flashcards
what is the neural explanation?
the role hypothalamus - dual feeding centre theory
what does the hypothalamus do in the brain?
important role in the regulation of hunger - found by research when we cut out different parts of a rats brain.
what is meant by the lateral hypothalamus and what does it trigger?
the feeding centre - produces neurotransmitter called neuropeptide which stimulates LH and brings about feeding.
triggers - HUNGER
what is meant by the ventro-medial hypothalamus and what does it trigger?
known as the satiety centre or the off switch. once feeding has taken place glucose levels rise and cells in the VMH detect this. also activity in the LH is inhibited
triggers - SATIETY (feeling full)
what evidence is there to support the role of the hypothalamus in the control of eating?
-found damaging the rats lateral hypothalamus caused aphagia - rats stopped eating and damage to the VMH caused rats to never feel full and become obese.
what is a criticism of the findings from the rat studies into the hypothalamus?
- unethical
- cannot extrapolate - e.g. ignores things like cultural effects on humans that rats don’t have
what evidence is there o support the role of the hypothalamus from humans?
post mortem carried out on women whose weight had doubled in just 2 years - she had a tumour on her VMH which affected her ability to turn her hunger switch off.
what are two hormones that effect our control in eating?
- ghrelin
2. leptin
how does ghrelin work as a hormonal mechanism in how we control our eating?
produced by the stomach - it signals how much time has elapsed since we late ate. as the levels rise, the stomach empties and they fall rapidly after a meal.
how does leptin work as a hormonal mechanism in how we control our eating?
produced by fat cells - levels rise as the amount of fat stored in body increases. detected by the VMH, leptin signals high levels of fat so appetite is suppressed.
what does leptin do when someone doesn’t eat?
fat stores decrease and the levels of leptin fall which signals the lateral hypothalamus to trigger hunger.
what research is there to support the hormonal mechanisms in the control of eating?
pps wither had a placebo injection of a ghrelin injection - significant increase in the amount of food they ate in the ghrelin condition.
what research is there to support the hormonal mechanisms in the control of eating? 2
some humans are unable to produce leptin and consequently become extremely obese - treated with leptin hormone therapy - research has shown that patients lost more than 40% of their body weight over 18 months.
what is an issue of hormonal mechanisms?
obesity may be due to the environment - deterministic
