Role of Acetyl CoA in many pathways

[betterfuture]

I am just trying to get an overall idea of Acetyl CoA and how it effects the different pathways. Here is what I know so far:

When cells need ATP,
Glucose-->Pyruvate-->Acetyl CoA-->ATP

When cells have met energy needs
There is a buildup of Acetyl CoA which,

• inhibits Pyruvate Dehydrogenase Complex
• Acetyl CoA now goes towards making palmitate (Fatty Acid Synthesis)

I also know that there could also be increase in Acetyl CoA, and that results from Beta-Oxidation. This occurs when there is a need for glucose in the blood, correct? This increase in Acetyl CoA, in turn, stimulates pyruvate carboxylase, the enzyme which converts pyruvate to OAA for gluconeogenesis.

Am I getting this right? Am I missing anything else?

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[JKlay7]

Don't forget about acetyl CoA's role in ketone bodies during prolonged fasting

 

[betterfuture]

Yeah. That means when you haven't had food for long periods of times and not like right after you sleep. Those are two different states, right?

So during the fasting state, beta oxidation occurs, the breaking of fatty acids in order to produce acetyl CoA. So I am a little confused. Is the Beta oxidation occurring to supply the cells with glucose, or the blood with glucose?

 

[JKlay7]

So to answer your last question, if i understand everything correctly, the purpose of beta oxidation is to produce energy (ATP). Not to supply the cell with glucose. FA's are a better store of energy (makes more ATP when broken down) and we get 9 kcal of energy per gram (i think?) and 4 kcal from carbs. Sooo.. when our body runs low of on glucose, glucagon stimulates breakdown of glycogen for glucose. The glycogenolysis can then be used for cell respiration or just to keep our blood glucose levels at normal levels. Now, when we run start running low on glycogen reserves, our body decides to stop using the circulating glucose for energy and looks for a more efficient source of energy. The FAs that we synthesized into palmitate (16c) earlier, for example, then gets carried into the mitochondria to get broken down, producing lots of NADH, FADH2 and Acetyl Coa. The NADH and FADH2 just go straight to the ETC while the Acetyl Coa can go directly to the TCA cycle without wasting time with glycolysis. In that way, we can keep our blood glucose levels normal and still produce lots of energy. I hope i got everything correct. Let me know if you got anymore questions.