Brain Metabolism

Question 1

3 fate of glucose in brain

Answer 1

1. Glucose needed in brain development
2. Glycosis -> 2 ATP
3. Glucose provide precursor for NT such as GABA

Question 2

What happen in Hypoglycemia ?

Answer 2

1. Hypoglycemia is sense by ventromedial hypothalamus
2. Suppression of insulin
3. Increase counterregulatory hormones

Question 3

Counterregulatory system in hypoglycemia

Answer 3

1. Glucagon (rapid)
   - glycogenolysis & gluconeogenesis
2. Epinephrine
   - glycogenolysis
   - gluconeogenesis
   - lipolysis
   - decrease peripheral glucose uptake
3. GH (slow)
   - lipolysis
   - systemic glucose production
4. Autoregulation of liver
   - protect brain in severe hypoglycemia

Question 4

KB utilisation to produce energy

Answer 4

• during starvation, brain use KB as source of energy
• in ketotic state, cerebral utilisation is increased in direct proportion to the degree of ketosis
• KB converted to Acetyl CoA
• then enter TCA cycle & oxidized

Question 5

Main KB

Answer 5

B-hydroxybutyric acid

Question 6

Why ammonia need to be remove ?

Answer 6

• NH3 is very toxic to nerve cell & could lead to hepatic coma
• it become toxic because it reacts with a-ketoglutarate to form glutamate
• depletion of a-ketoglutarate then impair function of TCA cycle

Question 7

2 reactions to remove ammonia

Answer 7

1. Formation of glutamate from NH3 & a-ketoglutarate by Glutamate dehydrogenase
2. Formation of glutamine from glutamate & NH3 by glutamine synthase