Nueral And Hormonal Mechanisms

Question 1

Limitations of a homeostatic explanation:

Answer 1

for hunger to be adaptive it must both anticipate and prevent energy deficits

but hunger and eating are only triggered when energy resources are low which is incompatible with the harsh reality that systems evolved

if it were adaptive it would promote consumption that maintain bodily resources well above optimal level

food intake based solely on homeostatic mechanisms offer a limited perspective on eating behaviour

Question 2

Problems with the role of the lateral hypothalamus:

Sakurai et. al (1998)

Answer 2

damage to the LH cause deficits in other aspects of behaviour (i.e. thirst/sex) rather than just hunger

eating behaviour is controlled by neural circuits that run throughout the brain and not just the hypothalamus

S: although the LH plays an important role in controlling eating behaviour, it’s not the brains ‘eating centre’

Question 3

Research support for the role of ghrelin in appetite control:
Wren et. al (2001)

Answer 3

provided support for the role of ghrelin in appetite control Ina double-blind tidy of 9 healthy volunteers.

one group received ghrelin and the other saline infusion

results showed significant increase in food consumption in the ghrelin condition compared to saline with a mean difference of 28% between the 2 conditions

conclusion: ghrelin is important in food intake

Question 4

Lepton resistance:

Answer 4

some people develop resistance to leptin so it fails to control appetite and weight gain

this is due to leptin receptors not functioning properly and so cells fail to respond to the hormone

thus leptin resistance is often found in overweight/obese people making it harder for them to lose weight