Nerve conduction - Conduction of A.P.

Question 1

What is the all or non principle?

Answer 1

• Action potential either occurs or not
• Once initiated, action potential conducted all the way down axon to end
• Remains the same size without increase or decrease in size of charge
• When axon splits, AP of same size (i.e., does not diminish) is conducted down both axons
• Variations in intensity of sensory stimulus or motor response results from change in rate of neuron firing, i.e., faster firing - greater intensity

Question 2

Passive conduction of depolarization (electrical impulse) - What does a sub-threshold depolarization produce?

Answer 2

a disturbance in the neuron membrane (change in electrical charge) that becomes smaller as it moves away from the point of stimulation

• • This type of conduction is passive, i.e. without changes in membrane permeability
    a. axon is acting like an electrical cable

Question 3

In myelinated axons, where do action potentials occur?

Answer 3

At the Nodes of Ranvier where membranes are not myelinated and are conducted passively in myelinated areas
- This conserves energy because none is used for passive conduction and is faster because passive is faster than active conduction