Appetite

Question 1

What are the symptoms of metabolic syndrome?

Answer 1

• insulin resistance
• central obesity
• dyslipidaemia (high levels of VLDL and LDL, low levels of HDL)
• hypertension

Question 2

Where is the appetite control centre located?

Answer 2

arcuate nucleus in the hypothalamus

Question 3

What is the difference between the function of primary and secondary neurones of the arcuate nucleus?

Answer 3

Primary: sense metabolite levels and respond to hormones
Secondary: synthesise input from primary neurones and co-ordinate a response via the vagus nerve

Question 4

Describe the difference between excitatory and inhibitory primary neurones

Answer 4

Excitatory- Stimulate appetite via release of neuropeptide U and agouti-related peptide

Inhibitory- Suppresses appetite by releasing pro-opiomelanocortin (POMC). POMC released in response to full stomach, causing endorphin release (feelings of euphoria and tiredness)

Question 5

What are some of the products of enzymatic cleavage of POMC?

Answer 5

• polypetide prohormone
• enzymatic cleavage can result in:
• Beta endorphin
• ACTH
• alpha-melanocyte stimulating hormone (alpha-MSH). Acts on melanocortin 4 receptors to suppress appetite

Question 6

Describe the effect of PYY on appetite

Answer 6

• peptide hormone
• released from wall of small intestine
• decreases appetite

Question 7

Describe the effect on insulin on appetite

Answer 7

-works via same mechanism as leptin

Question 8

Describe the effect of leptin on appetite

Answer 8

• peptide hormone
• secreted by adipocytes into bloodstream
• stimulates inhibitory neurones and inhibits stimulatory neurones
• ‘satiety hormone’
• induces uncoupling protein expression in mitochondria causing heat loss

Question 9

Describe the effect of ghrelin on appetite

Answer 9

• peptide hormone
• released from wall of empty stomach
• activates stimulatory neurones of arcuate nucleus
• full stomach inhibits ghrelin release

Question 10

Describe the effect of amylin on appetite

Answer 10

• secreted by beta cells of pancreas
• reduces appetite
• reduces glucagon secretion and slows gastric emptying

Question 11

What is the Barker hypothesis?

Answer 11

The experience of the foetus in utero during development somehow determines the future health of the individual

Question 12

What is an epigenetic trait?

Answer 12

a stably inherited phenotype resulting from changes in a chromosome without changes in DNA sequence