Question

1. A typical ion channel radius is about 1 nm (nanometer), and the thickness of the...

1. A typical ion channel radius is about 1 nm (nanometer), and the thickness of the cell membrane is about 7 nm. The concentration of Na+ ions inside a mammalian heart cell is about 0.6 ions/nm3, and in the fluid surrounding the cell is about 6.0 ions/nm3. The diffusion constant for ions is about 109 nm2/s (nanometers2/second). If the channel were just an open cylinder, how many ions per second would flow through the channel and in which direction? Is the flow from the inside to the outside or from the outside to the inside?

  

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