Ion channels

There are three types of ion channels:

1) Voltage-Gated ion channels

 e.g. Na⁺ and K⁺ channels found in nerve and muscle cells

2) Ligand Gated ion channels

 e.g. nAch receptor

3) Intracellular messenger-gated ion channels

By measuring the current of a single ion channel in a single cell we can learn three things: The conductance of the channel, the open state probability of the channel, and the selectivity of the channel (i.e. which ions move across the channel).