lecture 33

Question 1

What are Ketone bodies?

Answer 1

-Ketone bodies are water-soluble forms of partially metabolized fatty acids, and include acetone, acetoacetate, and B-hydroxybutyrate.

Question 2

Are Acetone, acetoacetic acid and beta-hydroxybutyric acids ketones?

Answer 2

• Acetone contains a ketone group (Technincally a ketone)
• Acetoacetate contains a ketone and a carboxyl group (Technically it is)
• Beta-hydroxybutyric acid is technically not a ketone. but still under the ketone category even though it isnt

Question 3

Why is the term ketone bodies is just a misnomer?

Answer 3

because even though Beta-hydroxybutyric acid is not a ketone its still put under that category.

Question 4

When do ketone bodies form?

Answer 4

• During starvation and carbs are not available. or not properly utulized due to insulin deficiency.
• Ketone bodies will form in the mitochondria from acetyl-CoA. These ketone bodies are normal metabolites but may apear in abnormally high amounts during conditions of uncontrolled type I diabetes.
• Ketogenesis (ketone body synthesis) occurs whenever fatty acid levels are elevated in the blood or as a result of high fat low carb diet (Atkins)

Question 5

Acetoacetate has 3 fates:

Answer 5

1- It can directly enter the blood
2-It can be reduced by NAD+ dependend hydrogenase to B-Hydroxybutyrate which enters the blood.
3-It can be spotaneously decarboxylated in which nonenzymatic reaction reaction releases CO2 and Produces Acetone.

Question 6

What is acetone breath?

Answer 6

Acetone is volatile, it is expired by the lungs and thats why its called acetone breath.

Question 7

How do tissues use acetoacetate for fuel?

Answer 7

They turn int back into acetyl CoA through ketone body oxidation.

Question 8

How do tissues use beta-hydroxybutyrate for fuel?

Answer 8

It is converted back into acetoacetate by beta-hydrobutyrate dehydrogenase, turned back into aceyl CoA.

Question 9

How is the fuel consumed during starvation?

Answer 9

A typical 70 kg man has fuel reserve about 161k kcal which is caloric needs for 1-2 months.

• Carbohydrates is consumed within a day
• Even under starvation blood glucose levels must be maintained above 2.2 mM.
• First priority is to provide sufficient glucose to the brain and other tissues.
• The second priority is to preserve protein which is shifted by spending fatty acids.
• Motion is vital to animals thats why muscle mass must be presereved.