Int 6: Homeostasis and Obesity

Question 1

What do a) orexigenic and b) anorexigenic signals do

Answer 1

a) Stimulate food intake
b) Relays a feeling of fullness

Question 2

What happens if you block (ablate) orexigenic neurons?

Answer 2

Starvation

Question 3

Which ones are which?

a) POMC
b) NPY/AgRP

• Orexigenic
• Anorexigenic

Answer 3

a) Anorexigenic
b) Orexigenic

• Both are sensitive to peripheral hormonal signals
• Both interact reciprocally to signal metabolic state to other brain areas (e.g. Ghrelin)

Question 4

Selective deletion of leptin receptor in neurons leads to a)__________. Leptin b)_________ POMC mRNA expression and excites (b) cells. Therefore a lack of leptin / receptor means the mouse c)_____________

• Anorexia / Obesity
• Increase / Decrease
• Always feels full / never feels full

Answer 4

a) Obesity
b) Increases
c) Never feels full

Question 5

How does leptin resistance come about? and what is the big change that occurs as a result of leptin resistance?

Answer 5

1) As body fat increases, leptin levels also increase
2) Leptin target sites become insensitive to leptin
3) This is due to a CHANGE in signal transduction
4) Can be restored by reducing circulating leptin

Question 6

What are 3 complications that happen during PREGNANCY that obesity is a large risk factor for?

Answer 6

1. Gestational diabetes (GDM)
2. Venous thrombosis (VTE)
3. Pre-eclampsia (PET)

Question 7

Name 4 complications during LABOUR that occur in obese people

Answer 7

• Prolonged labour
• Increase caesarean
• Post partum haemorrhage
• Increased child size

Question 8

To save the ball achey questions here’s a note:

Post-natal complications:
- Wound infection
- Lower rates of breast feeding

Immediate foetal implications:
- Miscarriage
- Spina bifita
- Stillbirth

Factors affecting foetal nutrients:
- Blood nutrients
- Placental blood flow
- Placental nutrient transport activity

Question 9

The arcuate nucleus contains neurons that synthesise and release WHAT

Answer 9

Neuropeptide Y

Question 10

• in most cases of obesity, Leptin levels are high and Ghrelin levels are LOW
• Insulin, Leptin and Ghrelin are HORMONES
• A glucose tolerance test measures how well glucose is absorbed from the gut