insulin vs glucagon

[pr0digals0n]

hey everyone, I have a quick question.

I understand that glucagon wants to increase the blood concentration of circulating glucose because their is a shortage. however, I dont understand how that inhibits glycolysis. I get that if glycolysis is functioning then that means there is less glucose to pump into the blood stream, but isnt the whole point of pumping it into the bloodstream to get more energy by breaking it down in a certain cell like a muscle cell? I dont get how thats not conflicting?

is it because glucacon acts first and increases glucose concentration in bloodstream then it its levels decrease allowing for insulin to act and cause it to be taken up for glycolysis to start? that would make more sense if its true.

also, if insulin increases the action of glycolysis, doesnt that mean its breaking down glucose(catabolism) when it should be increasing glycogenesis and TGA/fatty acid synthesis? I thought it increases storage, not breakdown?

im so confused..

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[theonlytycrane]

The liver is doing the glucose regulation.

If blood glucose levels are low, glucagon stimulates glycogen breakdown (to increase blood glucose levels) and inhibits glycolysis in the liver. Muscle cells downstream won't also be starved of glucose.

If blood glucose levels are high, insulin stimulates glucose intake which can be used for glycolysis, glycogenesis, or fat storage.

 

[pr0digals0n]

The liver is doing the glucose regulation.

If blood glucose levels are low, glucagon stimulates glycogen breakdown (to increase blood glucose levels) and inhibits glycolysis in the liver. Muscle cells downstream won't also be starved of glucose.

If blood glucose levels are high, insulin stimulates glucose intake which can be used for glycolysis, glycogenesis, or fat storage.

ok so this confirms a theory I had before. so glucagon is really acting on the liver, right? its not really directly effecting other tissue?

 

[theonlytycrane]

yep! Because the glucose storage that needs to be released (glycogen) is in the liver. The other tissues just go with the flow and take in glucose from the blood stream as needed (at least that's how I simplify the system for MCAT purposes).