Ketone Body Metabolism

Question 1

where are ketones formed? why?

Answer 1

liver- lower rates of TCA cycle has acetyl CoA build up

Question 2

where are ketones used?

Answer 2

muscle and CNS (2-3 days of starvation)

Question 3

how do ketones travel?

Answer 3

in the blood

they are soluble

Question 4

does the liver use ketones?

Answer 4

no sends them out

Question 5

what are the steps of ketogenesis?

Answer 5

1. acetylCoA + acetylCoA –> acetoacetyl CoA
2. add another acetyl CoA-> 3-hydroxy-3-methyl glut aryl CoA (HMG CoA)
3. remove an acetyl CoA- acetoacetate
4. 2 options:
   a- reduced to betahydroxygutyrate by NAD
   b- spontaneous loss of CO2 to form acetone

Question 6

what happens to acetone?

Answer 6

exhaled as CO2

no way to recapture the carbons lost

Question 7

what does an untreated diabetics breath smell like?

Answer 7

acetone- high rate of ketone loss because high rate of ketogenesis

Question 8

how are ketones used for energy?

Answer 8

betahydroxybuterate is reduced to acetoacetate by NAD
+ succinyl CoA–>acetoacetyl CoA
+ CoA–> 2 acetylCoA–> enter TCA cycle

Question 9

how do ketogenic diets work?

Answer 9

force TAG mobilization, acetyl CoA builds up–>ketogenesis- uses a lot of energy

Question 10

how is ketogenesis regulated?

Answer 10

TAB mobilization (lipolysis)
glucose available