I couldn't find much in my notes or the power point about it. But I googled it and came with like.. it had to do with maintaining balance or something.
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The Na+/K+ pump is extremely important in many cell types..
In neurons it's important for potentiating action potentials as someone else described in an earlier answer.
In many other cells it helps maintain electrochemical gradients of OTHER ions... here's how that works: The pump causes Na+ and K+ to move against their concentration gradient; Na is pumped out and K is brought in, and they want to be just the opposite.
So, once Na+ is pumped out, it really wants to move down its concentration gradient back into the cell. Many cells have channels that are not ATP dependent that Na can move through to get back into the cell where the concentration is lower. In many cells, these channels or transporters are symporters and will use the movement of Na to also move another ion either into or out of the cell (for example chlorine or iodine or something like that.)
The same idea works with K... Many cells have K+ leak channels that let K+ leave the cell again down it's concentration gradient, and these are sometimes coupled to other ion channels.
One good example is the movement of glucose from the lumen of the intestine into the cell:
Na+ is actively being pumped out of the cells lining the intestine, against their gradient, into the interstitial fluid. This action keeps the concentration in the cell of Na+ lower than outside of the cell. On the lumen side of the cell, there are symport channels that carry both Na+ and glucose into the cell. Glucose can only be brought into the cell through this channel if Na+ is also brought in with it...since the concentration of the Na+ in the cell is low (due to the ATPase activity) Na+ does want to be brought in, and it brings glucose with it. Glucose then moves across the cell and is passively transported out of the cell into the interstitial fluid where it can then enter the blood stream.
In neurons it's important for potentiating action potentials as someone else described in an earlier answer.
In many other cells it helps maintain electrochemical gradients of OTHER ions... here's how that works: The pump causes Na+ and K+ to move against their concentration gradient; Na is pumped out and K is brought in, and they want to be just the opposite.
So, once Na+ is pumped out, it really wants to move down its concentration gradient back into the cell. Many cells have channels that are not ATP dependent that Na can move through to get back into the cell where the concentration is lower. In many cells, these channels or transporters are symporters and will use the movement of Na to also move another ion either into or out of the cell (for example chlorine or iodine or something like that.)
The same idea works with K... Many cells have K+ leak channels that let K+ leave the cell again down it's concentration gradient, and these are sometimes coupled to other ion channels.
One good example is the movement of glucose from the lumen of the intestine into the cell:
Na+ is actively being pumped out of the cells lining the intestine, against their gradient, into the interstitial fluid. This action keeps the concentration in the cell of Na+ lower than outside of the cell. On the lumen side of the cell, there are symport channels that carry both Na+ and glucose into the cell. Glucose can only be brought into the cell through this channel if Na+ is also brought in with it...since the concentration of the Na+ in the cell is low (due to the ATPase activity) Na+ does want to be brought in, and it brings glucose with it. Glucose then moves across the cell and is passively transported out of the cell into the interstitial fluid where it can then enter the blood stream.
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