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:
“Always and everywhere children take an active role in the construction and acquisition of learning and understanding. To learn is a satisfying experience, but also, as the psychologist Nelson Goodman tells us, to understand is to experience desire, drama, and conquest.”
—Carolyn Edwards (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)
“The curse of me & my nation is that we always think things can be bettered by immediate action of some sort, any sort rather than no sort.”
—Ezra Pound (1885–1972)
“Most days I feel like an acrobat high above a crowd out of which my own parents, my in-laws, potential employers, phantoms of “other women who do it” and a thousand faceless eyes stare up.”
—Anonymous Mother. Ourselves and Our Children, by Boston Women’s Health Book Collective, ch. 2 (1978)