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July 22, 2025, 11:34:15 pm

Author Topic: Glucose and insulin  (Read 1151 times)  Share 

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Smiley_

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Glucose and insulin
« on: March 29, 2013, 10:58:00 am »
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So glucose is broken down by glycolysis
and insulin also breaks down glucose 
is what im thinking right.

Insulin breaks down the glucose in the food we eat and glycolysis  breaks down glycogen for energy?

Im a little confused.

thanks

Russ

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Re: Glucose and insulin
« Reply #1 on: March 29, 2013, 11:09:46 am »
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Glycolysis breaks down glucose.
Glycogenolysis breaks down glycogen.

Glycogen is a different molecule to glucose, so requires a different process.

Insulin has nothing to do with the breakdown of glucose, it just promotes the uptake of glucose into cells, where it can be broken down. It does this for all glucose (your body can't distinguish between glucose from outside and inside the body)

AbominableMowman

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Re: Glucose and insulin
« Reply #2 on: March 29, 2013, 11:09:56 am »
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Insulin does not simply 'break down glucose' as such. Insulin acts on the cells of the liver, muscles and fat tissue and stimulates them to remove glucose from the blood, to be used immediately or stored as glycogen. The opposite occurs when glucagon acts on liver and muscle cells, causing them to break down glycogen and return glucose into the bloodstream. Insulin and glucagon work together to maintain blood sugar levels, they're just homeostatic mechanisms.
Meanwhile glycolysis is a process within cellular respiration, where glucose is broken down (within the cell) into pyruvate molecules and ATP in order to facilitate aerobic or anaerobic respiration.
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Smiley_

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Re: Glucose and insulin
« Reply #3 on: March 29, 2013, 11:16:39 am »
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ok thanks

Yacoubb

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Re: Glucose and insulin
« Reply #4 on: March 29, 2013, 04:42:22 pm »
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So before explaining what insulin does, you need to be aware of the fact of what homeostasis actually is. Homeostasis is the maintainance of a relatively stable environment within narrow ranges. One of the homeostatic mechanisms involves the regulation of blood glucose level, and two hormones (protein-based) are involved in this maintained equillibrium; insulin and glucagon. Both of these hormones are produced by the pancreas. Insulin is synthesised in beta cells of the pancreas, while glucagon is synthesised in the alpha cells of the pancreas.

When blood glucose level is too low, and is out of the narrow range of which is it homestatically regulated at, glucagon is synthesised by the alpha cells. The glucagon is then transported via the blood-stream to liver/muscle tissues, or effector muscles/cells, telling them to break down the glycogen into glucose. Remember back in biomacromolecules, glycogen is a complex carbohydrate polysaccharide made of branched chains of glucose monomers. When the glycogen is broken down, glucose is released into the blood stream, increasing the blood glucose level to then be within the homeostatic range of blood glucose level, which I think (correct me if I'm wrong), is betwen 3 and 4.

When blood glucose level is too high, the beta cells synthesise insulin. This protein based hormone is synthesised and travels via the bloodstream to the muscle/tissue cells to send a message to them to increase the rate of removing glucose from the blood and storing it as glycogen, when glucose forms into this polysaccharide in the condensation reaction. By doing so, blood glucose level is lowered until it is met within the narrow range that homeostasis dictates.

So rather than thinking it is immediately insulin or glucagon which causes an increase/decrease in blood glucose level, they are merely chemical messengers that act on the muscle/liver tissue target cells to either remove glucose from the blood and store it as glycogen, or break down glycogen in catabolism in order to then release it into the bloodstream and increase blood glucose level.

Hope this helped :)

Russ

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Re: Glucose and insulin
« Reply #5 on: March 29, 2013, 04:47:08 pm »
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RE: BGL maintenance, the range is 3.5-5.5 or 4-6 depending on what textbook you read, but it doesn't particularly matter for your purposes

It's probably also worth clarifying that glucagon and insulin are being produced constantly, irrespective of the blood glucose level. You don't suddenly transition from a "no insulin" to "insulin" state when the [glucose] is over a certain amount; there's a consistent alteration of secretion in response to feedback.
« Last Edit: March 29, 2013, 04:49:39 pm by Russ »

Yacoubb

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Re: Glucose and insulin
« Reply #6 on: March 29, 2013, 04:48:40 pm »
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RE: BGL maintenance, the range is 3.5-5.5 or 4-6 depending on what textbook you read, but it doesn't particularly matter for your purposes

Thanks for that - I'd just say that BGL maintanance is about 3-6 :) Thanks Russ!