Control of appetite Flashcards
Where in the nervous system is the centre for appetite control?
-Arcuate nucleus
By what two general means is appetite controlled?
- Nervous system
- Hormones
What are the two groups of neurones within the arcuate nucleus?
- Primary neurones
- Secondary neurones
What do the primary neurones do?
-Sense metabolite levels and respond to hormone levels
What do secondary neurones do to control appetite?
-Synthesise the input from the primary neurones and coordinate a response via the vagus nerve
What two sub-groups are there of primary neurones?
- Excitatory
- Inhibitory
How do excitatory neurones control appetite?
-Release neurotransmitter and stimulate appetite via secondary neurones
How do inhibitory neurones control appetite?
-Release neurotransmitter POMC which is enzymatically cleaved producing a-melanocyte stimulating hormone which suppresses appetite via secondary neurones
What else does POMC produce when enzymatically cleaved, what effect does this have?
- B-endorphin
- Part of the reward system, causes feelings of euphoria and tiredness
What two neurotransmitters do the excitatory neurones release?
- Neuropeptide Y (NPY)
- Agouti-releated Peptide (AgRP)
What type of hormone is ghrelin?
-Peptide
Where is ghrelin released from?
-Walls of the empty stomach
How does ghrelin help control appetite?
-Activates excitatory neurones and stimulates appetite
What inhibits ghrelin production?
-Stretch of the stomach walls
What effect does PYY have on appetite?
-Suppresses it
Where is PYY released from?
-Walls of small intestine
Where is leptin released from?
-Adipocytes of fat stores
What do leptin levels correlate to?
-Adipose tissue
How does leptin control appetite?
- Stimulates inhibitory nerves
- Inhibits excitatory nerves
- Suppresses appetite
What is leptin deficiency/insensitivity linked to?
-Obesity
How does insulin control appetite?
- Stimulates inhibitory nerves
- Suppresses appetite
What effect does amylin have on appetite?
- Suppresses appetite and slows gastric emptying
- Decreases glucagon secretion
Where is amylin secreted from?
-B-cells in the islets of langerhans in the pancreas
What is metabolic sydrome?
- The pattern of symptoms of:
- Insulin resistance
- dyslipidaemia
- glucose intolerance
- hypertension
- central obesity
