LG 1.6 Brain Metabolism

Question 1

What does the brain metabolize?

Answer 1

Glucose

Question 2

What type of metabolism does the brain normally have?

Answer 2

Aerobic

Question 3

What does the brain have Aerobic metabolism instead of anaerobic metabolism?

Answer 3

Aerobic metabolism yields 15 fold more energy than anaerobic.

Question 4

What uses the most energy in the brain?

Answer 4

80% of ATP that is hydrolyzed in the brain powers the formation and maintenance of ionic gradients.

Question 5

What type of diffusion do GLUT’s use?

Answer 5

Facilitated diffusion

Question 6

What is the function of GLUT transporters?

Answer 6

Facilitate the movement of glucose through membranes by providing a channel. In the absence of a pore, glucose cannot get through a membrane.

Question 7

What GLUT Transporter and what is the functioning concentration in the Liver?

Answer 7

GLUT 2, 300 mg/dL

Question 8

What tissues use GLUT 4 and what is the normal functional concentration?

Answer 8

• Muscle and Adipose

- 90 mg/dL

Question 9

What GLUT transporters does the brain have and what is the normal functioning concentration?

Answer 9

• GLUT 1 and GLUT 3

- 20 mg/dL

Question 10

What cells in the brain use GLUT 1?

Answer 10

Blood Brain Barrier endotheilial cells (astrocyte)

Question 11

What cells in the brain use GLUT 3?

Answer 11

Neuronal cell membranes (neuron)

Question 12

What is the Michaelis-Menten enzyme kinetics?

Answer 12

-Mathematically describes the rate at which an enzyme catalyzes reactions.

Question 13

What does the Michaelis constant stand for?

Answer 13

The Km value of an enzyme indicates the concentration of substrate which is sufficient for the rate of catalysis to be half of the maximum rate of catalysis.

Question 14

What do astrocytes do with glucose?

Answer 14

Glycogen phosphorylase in astrocytes hydrolyze glycogen to glucose-6-phosphate.

Question 15

What do astrocytes release for energy use for neurons?

Answer 15

Lactate

Question 16

What are the only cells in the body that have glucose-6-phosphatase activity?

Answer 16

Only liver and kidney cells have glucose-6-phosphatase activity

Question 17

What does the brain do during starvation mode?

Answer 17

The Brain can supplement its fuel supply by substituting ketone bodies for glucose. The brain can catabolize two of them, acetoacetate and b-hydroxybutarate, to supplement glucose in generating energy.

Question 18

Where does most of the ketone bodies come from?

Answer 18

Draws upon fatty acids stores in adipose tissue that are released and converted into ketone bodies in the liver to supplement glucose in providing energy to the brain.

Question 19

What transports free fatty acids in the blood?

Answer 19

Albumen

Question 20

What process does the liver go through to produce glucose for the brain?

Answer 20

Gluconeogenesis to regenerate the glucose for the brain which tends to deplete citric acid cycle intermediates.

Question 21

What is a precursor to make ketone bodies or cholesterol?

Answer 21

3-hydroxy-3-methyl glutaryl CoA

Question 22

What is HMG-CoA reductase?

Answer 22

Reduces 3-hydroxy-3-methyl glutaryl CoA to Mevalonate, the modular building building block for cholesterol

Question 23

What is HMG-CoA Lyase?

Answer 23

Lyses 3-hydroxy-3-methyl glutaryl CoA leading to ketone body synthesis.