Mixy246
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Hello, I just need help making sure I understand Selective Reaborption.


Selective Reaborption
1) Na+/k+ pump actively transports Na+ ion from the Proximal convoluted tubules cells into the blood, against its concentration gradients. This decrease the conc of Na+ ion in the PCT cells.

2) due to the low conc of Na+ ion in the PCT cells, Na+ ions diffuse in to the Wall of the PCT from the filtrate in the PCT lumen, by facilitated diffusion. Co-transporter proteins also allow the diffusion of glucose and amino acids along with Na+ ions in to the wall of the PCT wall.

3) the increase in conc of glucose and amino acids in the PCT cells cause them to diffuse into the blood down their conc gradient

4) the Reaborption of glucose l, amino acids and Na+ cause the cells of the PCT to have a low water potential, therefore water enter the Cells and then the blood by osmosis.


If this is correct or need some stuff added or taken away please let me know.

Thanks ^•^
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Jpw1097
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(Original post by Mixy246)
Hello, I just need help making sure I understand Selective Reaborption.


Selective Reaborption
1) Na+/k+ pump actively transports Na+ ion from the Proximal convoluted tubules cells into the blood, against its concentration gradients. This decrease the conc of Na+ ion in the PCT cells.

2) due to the low conc of Na+ ion in the PCT cells, Na+ ions diffuse in to the Wall of the PCT from the filtrate in the PCT lumen, by facilitated diffusion. Co-transporter proteins also allow the diffusion of glucose and amino acids along with Na+ ions in to the wall of the PCT wall. Likewise, the Na+/K+-ATPase is located in the basolateral membrane of the cells lining the PCT, and actively pumps 3 Na+ out of the cell into the interstitial fluid for every 2 K+ that it pumps in. The Na+ can then diffuse from the interstitial fluid into the blood in the peritubular capillaries/vasa recta.

3) the increase in conc of glucose and amino acids in the PCT cells cause them to diffuse into the blood down their conc gradient

4) the Reaborption of glucose l, amino acids and Na+ cause the cells of the PCT to have a low water potential, therefore water enter the Cells and then the blood by osmosis.


If this is correct or need some stuff added or taken away please let me know.

Thanks ^•^
Yes, that looks absolutely fine for selective reabsorption in the PCT. Of course, there is also selective reabsorption in the loop of Henle, the DCT and also the collecting duct. Amino acids and glucose diffuse into the interstitial fluid using transporters that are in the basolateral membrane of the PCT (the membrane of the PCT cell in contact with the interstitium) by facilitated diffusion, and then they diffuse into the blood. Likewise, the Na+/K+-ATPase is located in the basolateral membrane of the cells lining the PCT, and actively pumps out 3 Na + into the interstitial fluid for every 2 K+ that it pumps into the cell. The Na+ along with glucose, amino acids and other ions that have been reabsorbed diffuse from the intersitial fluid into the peritubular capillaries/vasa recta.

Seems fine to me.
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