Neurophysiology and stuff Flashcards
What are the two factors that determine the membrane potential of the cells?
-Selective permeability to certain ions -Concentration gradient of permeant ions across the membrane.
What is the resting membrane potential?
Is the electrial potential across the membrane generated by the diffusion of ions down their concentration gradient.
What is the equilibrium potential?
Is the potential at which there is no net movement of ions across the plasma membrane.
What is the typical movement of Ca+ and Na+ at resting membrane potential?
They flow inward, causing depolarization.
What is the typical movement of K+ at resting membrane potential?
It flows outward, causing hyperpolarization.
What is an action potential?
A sudden change in Vm due to movement of ions.
What are the two factors that affect the action potential?
-Direction of the movement of ions (influx or efflux) -Charge of those ions.
What generates the upstroke of the action potential?
The upstroke is generated by an entrance of Na+ that cause a depolarization.
What are the two different types of depolarizing stimulus?
-Subthreshold depolarizing stimulus (not sufficiently large to fire an AP). -Threshold depolarizing stimulus.
What generates the downstroke of the action potential?
The downstroke is generated by a displacemente in time of the opening of K+ channels that cause a delay in K+ efflux.
Describe absolute refractory period:
No stimulus, however strong, can fire a second action potential.
Describe relative refractory period:
A strong stimulus can fire a second action potential.
Describe the peculiarity of the outward movement of K+
It moves outward because concentration gradient exceed electrical gradient.
Describe graded potential:
It doesn’t travel as far as action potential, instead it dissipates due to current leaks out of the axon. It can reach threshold (and thus fire AP) only if summated.
What is neurotransmission?
The process that generates action and graded potential.
