Role in Action Potential
- See main article: Action potential
Voltage-gated sodium channels play an important role in action potentials. If enough channels open when there is a change in the cell's membrane potential, a small but significant number of Na+ ions will move into the cell down their electrochemical gradient, further depolarizing the cell. Thus, the more Na+ channels localized in a region of a cell's membrane, the faster the action potential will propagate, and the more excitable that area of the cell will be. This is an example of a positive feedback loop. The ability of these channels to assume a closed-inactivated state causes the refractory period and is critical for the propagation of action potentials down an axon.
Na+ channels both open and close more quickly than K+ channels, producing an influx of positive charge (Na+) toward the beginning of the action potential and an efflux (K+) toward the end.
Ligand-gated sodium channels, on the other hand, create the change in the membrane potential in the first place, in response to the binding of a ligand to it.
Read more about this topic: Sodium Channel
Famous quotes containing the words role in, role, action and/or potential:
“If women’s role in life is limited solely to housewife/mother, it clearly ends when she can no longer bear more children and the children she has borne leave home.”
—Betty Friedan (20th century)
“A few [women] warrant our attention not because they have the answer but because they have rejected the mentality that insists there must be one answer. What makes them role models is not how much or how little they work, how many or how few hats they wear, but rather how well they understand, and accept, that for all rewards there will be commensurate sacrifice; for all gains, some loss; for any pleasure, some pain.”
—Melinda M. Marshall (20th century)
“This nation asks for action, and action now.”
—Franklin D. Roosevelt (1882–1945)
“Laughing at someone else is an excellent way of learning how to laugh at oneself; and questioning what seem to be the absurd beliefs of another group is a good way of recognizing the potential absurdity of many of one’s own cherished beliefs.”
—Gore Vidal (b. 1925)