Active transport and glucose in the small intestine Watch

EmmaaaN97
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Hi guys, I’ll try and make this as short as possible.

I read on BBC Bitesize that In the small intestine, glucose is absorbed by active transport into the villi, to be passed into the bloodstream and taken around the body.

Yet this contradicts other stuff I’ve read who explain its actually a 2 stage process of co transport of glucose and sodium into the epithelial cells, and facilitated diffusion of just glucose going into the bloodstream.

All I want to know is, what cell transport is used to transport glucose in the small intestine because I’m getting confused.

Thanks
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Jpw1097
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(Original post by EmmaaaN97)
Hi guys, I’ll try and make this as short as possible.

I read on BBC Bitesize that In the small intestine, glucose is absorbed by active transport into the villi, to be passed into the bloodstream and taken around the body.

Yet this contradicts other stuff I’ve read who explain its actually a 2 stage process of co transport of glucose and sodium into the epithelial cells, and facilitated diffusion of just glucose going into the bloodstream.

All I want to know is, what cell transport is used to transport glucose in the small intestine because I’m getting confused.

Thanks
Glucose is absorbed by secondary active transport. Sodium is removed from the enterocytes (the cells lining the intestines) using the sodium-potassium pump (3 sodium ions are pumped out of the cell into the bloodstream in exchange for two potassium ions which enter the cell via active transport). This creates an electrochemical gradient (low sodium in the enterocyte, high sodium in the intestinal lumen). This electrochemical gradient is used to drive glucose across the apical membrane into the enterocyte using the SGLT1 (sodium-glucose cotransporter). Once in the cell, glucose diffuses into the blood across the basolateral membrane using the GLUT2 transporters via facilitated diffusion.

Those two answers you’ve described don’t contradict each other, absorption of glucose uses secondary active transport (using the sodium-glucose cotransporter, SGLT1) and then facilitated diffusion from the enterocyte (intestinal cell) into the blood.
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EmmaaaN97
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(Original post by Jpw1097)
Glucose is absorbed by secondary active transport. Sodium is removed from the enterocytes (the cells lining the intestines) using the sodium-potassium pump (3 sodium ions are pumped out of the cell into the bloodstream in exchange for two potassium ions which enter the cell via active transport). This creates an electrochemical gradient (low sodium in the enterocyte, high sodium in the intestinal lumen). This electrochemical gradient is used to drive glucose across the apical membrane into the enterocyte using the SGLT1 (sodium-glucose cotransporter). Once in the cell, glucose diffuses into the blood across the basolateral membrane using the GLUT2 transporters via facilitated diffusion.

Those two answers you’ve described don’t contradict each other, absorption of glucose uses secondary active transport (using the sodium-glucose cotransporter, SGLT1) and then facilitated diffusion from the enterocyte (intestinal cell) into the blood.
Ahh thanks! I assumed when it was talking about diffusion it meant it was a passive process. Is there a source you used to give your answer as it might help me? Thanks
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Jpw1097
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(Original post by EmmaaaN97)
Ahh thanks! I assumed when it was talking about diffusion it meant it was a passive process. Is there a source you used to give your answer as it might help me? Thanks
I don't have an online source, although a google search will give you the same information that I have provided. A good textbook is medical physiology by Boron and Boulpaep - it is sometimes a bit advanced but it's a pretty good textbook.
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