Ketone bodies

[yjj8817]

Why is it that liver goes through all the trouble of making ketone bodies from acetyl coa when the ketone bodies are converted back to acetyl coa in the other tissues?

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[desertrat12]

Ketones are made when glucose stores are low, then, like you said, ketone bodies can be used by some non liver tissues to make acetyl coA and thus go on to make some atp. However, if glucose stores are low then the liver will turn to beta oxidation to make energy. Fatty acids go through beta oxidation and one of the products is acetyl coA. In order to go through beta oxidation, there needs to be coA avaliable. If the liver made acetyl coA and kept shipping it out the supply of coA would deplete, and the whole point to produce energy without glucose would be harmed due to a lack of coA for beta oxidation

 

[yjj8817]

Ketones are made when glucose stores are low, then, like you said, ketone bodies can be used by some non liver tissues to make acetyl coA and thus go on to make some atp. However, if glucose stores are low then the liver will turn to beta oxidation to make energy. Fatty acids go through beta oxidation and one of the products is acetyl coA. In order to go through beta oxidation, there needs to be coA avaliable. If the liver made acetyl coA and kept shipping it out the supply of coA would deplete, and the whole point to produce energy without glucose would be harmed due to a lack of coA for beta oxidation

But by converting acetyl coa that was provided by fatty acid to ketone bodies and shipping them out to other tissues, aren't you depleting coa?

Am I missing something?

 

[Labrat07]

From my understanding, the liver convert acetyl Coa to atp at first. Over time, excess NADH give a negative feedback to this process. So we have access Acetyl COA. Then we must convert them to ketone so it can travel through blood. I'm still hazy on this concept. If anyone have a condense solid explanation, please educate us.

 

[studentdocftw]

Keep in mind, the liver can't metabolize ketone bodies...so in a sense..it's "trapping" some energy that has to be used by other cells. Otherwise, the energy form of the liver and the rest of the body would be the same...resulting in the liver using the energy input that is desperately needed by other tissues. If the liver simply converted it to acetyl CoA, it wouldn't be as efficient...as some acetyl coa would be inevitably metabolized by the liver...conversely, if we convert it to ketones, well now the energy HAS to leave the liver...cause it can't do anything with it...and energy will reach the issues more effectively.

 

[basophilic]

I see ketone bodies simply as "packaging" molecules. The liver metabolizes some fat to get lots of acetyl-CoA and then "packages" this compactly into ketone bodies, which can be more easily delivered through bloodstream to other tissues. In a way, this makes sense because free acetyl-CoA is not that stable - it could potentially get hydrolyzed in the aqueous bloodstream. So maybe ketone bodies are an easier way to deliver acetyl-CoA-derived energy to tissues. This is just my speculation, though.