The Neuron & Action Potential

Question 1

What is a nerve?

Answer 1

• made up of many axons bundled together

Question 2

What is the resting potential?

Answer 2

• travels down the axon as NA+ and K+ are allowed to move down their electric chemical gradients

Question 3

What is depolarization?

Answer 3

• the sodium channels will automatically open if there is a slightly polarization detected nearby, where the resting potential starts to decrease where the difference is about -55MV

Question 4

What is repolarization/hyperpolarization?

Answer 4

• now the K+ channels, close and clean up begins as the Na+/K+ pumps begin to rest, restore the appropriate resting potential and return to the ions back to their proper places. As this is happening, the Na+ will not open and no action potential as possible until the resting potential is restored

Question 5

What is repolarization?

Answer 5

• is this area of the axon depolarizes, this depolarization causes other Na + channels to open further down the axon. This creates a domino effect as Na + channels start to open along the axon. This is the action potential travelling down the axon

Question 6

Action potential: (threshold, depolarization, repolarization, hyper polarization, refractory period) explain.

Answer 6

1. Resting potential:
   • electric potential across the membrane when the neuron is not stimulated
2. Action potential:
   • takes place when the threshold potential is reached at -55MV
3. It causes the sodium channel proteins to open and allow the sodium ions to quickly move along their electric chemical gradient (depolarization)
4. Sodium channels closed once electric potential flips to +30 MV. The channels will not open for a brief period (refractory period)
5. Potassium channel is now open and potassium ions, move across their own electric chemical gradients (repolarization)
6. Potassium channels close at -90 MV in the NA/K pumps work to restore the resting membrane potential hyperpolarization and repolarization)

Question 7

What are leak channels?

Answer 7

• also embedded throughout the membrane of the neuron are leakage channels. Potassium and sodium ions can leak out of the neuron through these leakage channels that are always open.

• these channels play a crucial role in maintaining the resting membrane potential of a neuron (-70mv)