Brief overview of resting membrane potential, active transport, and concentration gradients
What is the definition of Resting Membrane Potential?
Electrical potential between the intracellular and extracellular fluid in a neuron
What is Ohm's law?
I = v/r
(current) = (voltage)/(resistance)
What is a lipid?
What is the intra/extracellular fluid?
(in regards to electricity)
A conductor (ionized fluid)
What is the the resting membrane potential amplitude of the cell in comparison to the extracellular fluid?
-70 mV (so the inside of the cell is negative, and the outside of the cell is positive)
1 mV = .001V
In order to send signals, the neuron needs to be able to control the ________ ________
charges are associated with ____ which the cell can move in and out of the cell membrane by taking advantage of the ________ _________ and opening or closing the ____ ________ within the cell membrane
Ions will move from areas of ______ concentration to ______ concentration until ________ is met
Ion channels are ______ for certain ions, i.e. ______ ______ ______ etc.
What is equilibrium potential?
When electrical potential is equal in magnitude and opposite in direction to the concentration gradient, you get: ____ _____ _____ which is also known as the __________ ________
No net flux
Equilibrium potential is met when:
Flux due to ________ ___________ is equal to but opposite in direction to the flux due to ________ ________
The NA+/K+ Pump uses _____ and converts it to _____, differently put, it uses ______ because its ________
The NA+/K+ Pump moves 3 NA+ outside of the cell (to the extracellular fluid) and 2 K+ inside the cell (to the intracellular fluid), creating a slightly more positive extracellular charge.
The K+ tends to leak out of the cell, and the NA+ tends to leak into the cell, so The NA+/K+ Pump has to constantly work to maintain a dynamic constancy to maintain -70mV.
Graded Potentials are localized to an area and they are decremental, which means that the distance is proportional to the inverse of the polarization (depolarization or hyper polarization) they can also summate, which means they can be added
Steps in transmission of nerve impulses (6):
1. Polarization of the membrane (excess NA+ on outside, excess K+ on inside) this means that the intracellular fluid is more negative than the extracellular fluid
2. Resting potential gives the neuron a break: the neuron is inactive and polarized
3. Action Potential: Stimulus reaches the resting neuron and voltage gated ion channels open, allowing NA+ to flood in (cell is now depolarized +inside/+outside) As gates remain open and NA+ continues to flood in, the threshold for depolarization nears. Once this threshold is met, an action potential is created (point of no return) and the stimulus is transmitted.
4. Repolarization: NA+ continues to reside in the cell, gated ion channels open to allow K+ to move outside. This restores electrical balance (+inside/-outside) **opposite of what we started with
5. Hyperpolarization: when the K+ gates close, the neuron has more K+ on the outside and more NA+ on the inside (membrane potential is now lower than resting potential).
6. Refractory Period (everything back to normal): Na+ returns to the outside and K+ returns to the inside, during this time the neuron cannot respond to a stimuli
Between 0 and 1: Na+ rushes in
Between 2 and 3: threshold met, action potential created
Between 3 and 4: K+ exits the cell
At 5: cell becomes more negative than resting potential
At 6: cell normalizes to resting potential, stimuli can be received again
Action Potentials are:
____ or _____
Have lots of involvement with voltage-gated ion channels
All or none
Sodium voltage-gated channels are ______ and potassium voltage gated channels are ________ which aids in depolarization, repolarization, and hyperpolarization.