Psychology Case

Feeling hungry is one of the most basic biological drives to cause us to eat in order to stay alive. Humans can maintain a constant internal environment by a process called homeostasis. Interestingly, your weight is regulated by homeostasis and hence will influence our eating behaviour. Unfortunately, overall patterns of eating behaviour break the homeostatis rules slightly. 1) We don't usually wait before we feel hungry before we eat- we flow a set pattern

2) We feel full at the end of a meal which is long before nutritients have been absorbed.

Researchers have found that this are of the brain (hypothalamus) is linked to feeding- an early link was that patients with tumours on the basil hypothalamus became obese. Hetherington& Ranson demonstrated lesions on the hypothalamus caused rats to over-eat and become very obese. A lesion on the ventromedial hypothalamus(vmh) was a key area. It was assured therefore that the vmh controlled feeding behaviour i.e vmh is activated when full. 9 years later, Anand Et Al looked at lesions on the lateral hypothalamus and this caused them to stop eating. These studies were reinforced by electrical stimulation studies which found the opposite effect reinforcing the point that the hypothalamus is the feeding centre of the brain. There are a number of neurotransmitters that are linked with the increase or decrease of food intake.

1) Neuropetide y- if this is injected into rats who are already full, they still consume large amounts of food.

2)Galanin- found throughout the human brain and when injected into rats it increases their food intake

3) Bombesian- A neurochemical found to reduce food intake in rats and is also found in the neurotransmitter serotonin.

Nicotine usually reduces food intake and people who quit smoking generally put on weight. Marijuana and alcohol have been proven to increase hunger. ( due to their influence on neural pathway e.g. amphetamines influence the catecholamine pathway which suppresses hunger)

Cummings Et Al investigated food gherkin levels over time between meals(6 participants). Ghrelin fell immediately after a meal then slowly began to rise approaching the evening meal. They also interviewed the participants and found gherkin levels were correlated with the degree of hunger the participant felt. Only 6 participants which were male therefore generalising issues. Findings were correlated so causality issues. In terms of ethical issues the researchers got ethical clearance and participants were volunteered so obtained informed consent.

There are many approaches to understanding certain behaviour, social, cognitive.. Unfortunately, the biological neural explanations are considered by many to be reductionist .

1) Ethical to test on non human mammals procedure that could