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Discuss neural mechanisms involved in
Hunger is the motivation or drive to start Cannon and Washburn: Found that when
eating and satiety is the feeling of being the participant was not hungry, there were
full. Set point theory states that we have a
no contractions and hunger was reported
biologically determined standards around at the height of the contractions,
which our body weight is regulated, so if suggesting that stomach contractions
we eat too much or too little, homeostatic caused hunger.
mechanisms alter our metabolism and This was a case study so it's not
appetite to return us close to our original
generalisable to the entire population.
body weight. Lateral hypothalamus this There may be individual differences.
produces hunger, damage to this area There is no cause and effect, hunger may
results in dramatic reductions in food have caused the contractions, not the
intake. other way around.
Ventromedial hypothalamus this Passer et al: showed that feelings of
triggers a sense of feeling full, thereby hunger and satiety are experienced even
reducing appetite. when all the nerves from the stomach to
Paraventricular nucleus this is a the brain are cut. This indicates that other
cluster of neurons with receptors for neural mechanisms must play a role in
various transmitters that stimulate or triggering hunger e.g. ghrelin.
reduce appetite. Lutter et al: They starved mice for days to
increase the amount of ghrelin in their
systems, they compared these mice to
mice who were allowed to eat freely the
mice with increased ghrelin levels showed
more anxiety and more signs of
depression than the control group mice.
This suggests that food, hunger, stress
and anxiety levels are all associated.
GLUCOSTATIC THEORY Levels of energy source in the blood don't
Glucose is a simple sugar that we get usually drop to anywhere near the
from food that gives us energy. The threshold to trigger eating.
glucose that is not used immediately is Studies also indicate that body
stored in the liver and fat cells. Blood temperature increases just prior to
glucose levels are constantly monitored by spontaneous eating, increases still further
the sensors in the liver and the and then declines as eating stops. While
hypothalamus if levels are low stored some tissues need large amounts of
glucose is released. glucose for energy homeostasis, others
Changes in supply of glucose available e.g. the liver use fats. Biology is not the
generates signals to the brain that only initiator of eating.
regulate hunger and appetite.
Strong applications of research for
treatment (e.g. leptin injections)
Nonhuman animals in research
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There are a number of factors that can
make us feel more or less hungry e.g.
smell, habits or mood. Clearly
psychological factors as well as neural
mechanisms are at work.…read more