Biochem- Metabolic profile of the Brain

Question 1

What are the two major cell types of the CNS?

Answer 1

Neurons and Glia

Question 2

What are the two major kinds of Glial cells?

Answer 2

Oligodendrocytes

Astrocytes

Question 3

What is the fucntion of the oligodendrocyte?

Answer 3

Produce the myelin sheath in the CNS

Question 4

What is the major function of the Astrocyte?

Answer 4

-provide metabolic support and protection for the neurons

Question 5

What is the function of the microglia?

Answer 5

resemble macrophages, and appear to protect against infection and clear cellular debris

Question 6

The function of the _______ cell is to line the venticles and profuce, circulate and monitor the CSF.

Answer 6

Epindymal cell

Question 7

Tight junction between the BBB endothilial cells provide protection from most molecules, but what are some notable exceptions?

Answer 7

Caffeine

Nicotine

Alcohol

Cocaine

Question 8

How does the BBB transport molecules of which it needs large amounts?

Answer 8

-Facilitated diffusion (glucose) and active transport (ion concentraion)

Question 9

What are the two chief glucose transporters found in the brain?

Answer 9

GLUT1 and GLUT3

Question 10

What is special about the kinetics of the GLUT1 and GLUT3 transporters that make them well adapted for the BBB?

Answer 10

Low Km which permits constant and efficient glucose uptake.

Question 11

What is the main purpose of amino acid transporters?

Answer 11

-Promote the efflux of potentially harmful NT (gltamate) and the influx of essential amino acids (tyr and try)

Question 12

What is the theory behind sports drinks that contain branched chain amino acids?

Answer 12

-the BCAA compete with trytophan fo transport into the brain which reduces the trytophan uptake. Tryptophan is a precursor of 5-HT and melatonin which are involved in tiredness, relaxation and sleep.

Question 13

What enzyme is defficient in phenylketonuria?

Answer 13

-phenylalanine hydroxylase

Question 14

What is the action of phenylalanine hydroxylase?

Answer 14

-converts Phenylalanine to tyrosine

Question 15

What is the result of high levels of phenylalanine in PKU?

Answer 15

-mental retardation in infants and reduced uptake of tyrosine–> less melanin and therfore less pigementation

Question 16

How long does the BBB remain defective, even after a reversible inury?

Answer 16

2-3 weeks

Question 17

How high is the rate of blood supply to the brain?

Answer 17

Very high: 10x that of resting muscle or adipose tissue

Question 18

What is the brain’s main supply of energy? Can it absorb fatty acids?

Answer 18

• Glucose
• No it can not absorb fatty acids

Question 19

What does the brain use for energy during periods of starvation?

Answer 19

-Ketone bodies

Question 20

What are the principle uses of the energy that is required by the brain?

Answer 20

1. Transport processes (ion gradients)
2. Synthesis of NT and neuromodulators (peptide synthesis)

Question 21

How is NADPH provided through glucose metabolism?

Answer 21

-through the pentose phosphate pathway

Question 22

What are the main requirements of NADPH by cells in the CNS?

Answer 22

• Fatty acid synthesis (myelogenesis)
• Glutathione reductase (antioxidant)