Action Potential in Neurons

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Action Potential in Neurons
2013-09-29 13:45:17
Brain SLP Action Potential neurons

Brief overview of resting membrane potential, active transport, and concentration gradients
Show Answers:

  1. What is the definition of Resting Membrane Potential?
    Electrical potential between the intracellular and extracellular fluid in a neuron
  2. What is Ohm's law?
    I = v/r

    (current) = (voltage)/(resistance)
  3. What is a lipid?
    What is the intra/extracellular fluid? 

    (in regards to electricity)
    • An insulator
    • A conductor (ionized fluid)
  4. 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
  5. In order to send signals, the neuron needs to be able to control the ________ ________
    Membrane potential
  6. 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
    • concentration gradient
    • ion channels
  7. Ions will move from areas of ______ concentration to ______ concentration until ________ is met
    • higher
    • lower
    • equilibrium
  8. Ion channels are ______ for certain ions, i.e. ______ ______ ______ etc.
    • specific
    • Chloride
    • Potassium
    • Sodium
  9. What is equilibrium potential?
  10. 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
  11. Equilibrium potential is met when:
    Flux due to ________ ___________ is equal to but opposite in direction to the flux due to ________ ________
    • concentration gradient
    • electrical gradient
  12. The NA+/KPump uses _____ and converts it to _____, differently put, it uses ______ because its ________
    • ATP
    • ADP
    • Energy
    • Active
  13. The NA+/K+ Pump moves 3 NAoutside of the cell (to the extracellular fluid) and 2 Kinside the cell (to the intracellular fluid), creating a slightly more positive extracellular charge.
  14. The K+ tends to leak out of the cell, and the NAtends to leak into the cell, so The NA+/K+ Pump has to constantly work to maintain a dynamic constancy to maintain -70mV.
  15. 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
  16. Steps in transmission of nerve impulses (6):
    • 1. Polarization of the membrane (excess NAon outside, excess Kon 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 NAto flood in (cell is now depolarized +inside/+outside) As gates remain open and NAcontinues 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: NAcontinues to reside in the cell, gated ion channels open to allow Kto move outside. This restores electrical balance (+inside/-outside) **opposite of what we started with
    • 5. Hyperpolarization: when the Kgates 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
  17. Action Potentials are:
    ____ or _____
    Have lots of involvement with voltage-gated ion channels
    All or none
  18. Sodium voltage-gated channels are ______ and potassium voltage gated channels are ________ which aids in  depolarization, repolarization, and hyperpolarization.