PSYA3 Neurological Mechanisms in Eating

(AO1)

There is a complex web of Neurological Mechanisms that play a role in controlling eating and hunger.

One of these mechanisms involves the HYPOTHALAMUS...

• Hypothalamus has TWO PARTS that work in opposition to each other.
• This is called the DUAL PROCESS MODEL.
• The VENTROMEDIAL HYPOTHALAMUS (VMH) is called the 'satiety centre' and stops eating when we are full by monitoring stomach content levels and contractions through the vegus nerve.
• The LATERAL HYPOTHALAMUS (LH) is called the 'feeding centre' and makes us eat when blood sugar levels drop.
• The HYPOTHALAMUS works to maintain homeostasis in the body, so if a person has too many nutrients VMH is activated, and if too few nutrients LH is activated.

...

However the LH can be linked to two further parts of the Hypothalamus...

•  ARCUATE NUCLEUS (ARC)
•  PARAVENTRICULAR NUCLEUS (PVN)

The ARC consists of Hunger Neurones and Satiety Neurones

...

In Hunger Neurones...

• GHRELIN is a hunger hormone produced in the stomach (thought to cause the contraction feelings we experience during hunger)
• This stimulates the vegus nerve
• Which then stimulates  hunger neurones in ARC

• TASTE cells send neural signals to hunger neurones in ARC when tasty food is detected.

THEN...

• The Hunger Neurones in ARC send a chemical message (NPY and AgRP) to the PVN
• This stimulates PVN to send nerve impulses to the LH
• LH to releases Orexin which stimulates food seeking behaviour.

...

In Satiety Neurones...

• CHOLECYSTOKININ (CKK) is released during distension of the intestines, and stimulates satiety neurones in ARC. (Short Term)
• GLUCOSE levels in the blood are monitored by nerve cells, which then stimulate satiety neurones in the ARC
• LEPTIN is released by body fat which stimulates the satiety neurones in ARC. (Long Term)

THEN...

• The Satiety Neurones in ARC release Melanocortin
• This inhibits the action of NPY and AgRP
• So hunger is not experienced

~~~~~~~~~~~~~~~~~~~

(AO1)

Another neural mechanism involves NEUROTRANSMITTERS...

• Neurotransmitters (chemicals in the brain) may be linked to the PARAVENTRICULAR NUCLEUS (PVH…