DIFFUSION POTENTIAL, RESTING MEMBRANE POTENTIAL AND ACTION

DIFFUSION POTENTIAL, RESTING MEMBRANE POTENTIAL AND ACTION POTENTIAL A.N Malik Ion channels • They are integral proteins that permit passage of specific ions • Properties of ion channels • Selective: allow passage of ions of specific sizes or charge e.g. a sodium channel for only sodium ions…chloride ions wont pass • Exist in open or closed state: Open state when ions are passing through while closed state when no ions are passion thro • Conductance/permeability: probability that a channel is open. Opening and closing (gating) of a channel can be achieved thro: • Voltage gating/based on membrane potential e.g. activation and inactivation gates for sodium • Ligand gated: opened or closed by hormones, neurotransmitters or second messengers e.g. nicotinic receptor for acetylcholine at the motor end plate. When open it allows passage of both sodium and potassium The nicotinic acetylcholine-gated ion channel. Voltage gated sodium channels Diffusion and equilibrium potentials