ACTION POTENTIAL IN NERVE.pptx

PHYSIOLOGY OF ACTION POTENTIAL

1. ACTION POTENTIAL PREPARED BY FATIMA SUNDUS

2. Sodium inside the cell is 14meq\L and out side is 142 Potassium inside is 140 and outside is 4

3. We know that the inside of the nerve membrane is negative with respect to the outside (RMP=—90 mv) When an effective stimulus (threshold or suprathreshold ) is applied, the electrical charge on the membrane is reversed: at the active part of the nerve fibre the outside becomes negative as compared to the corresponding region in the interior. This is called DEPOLARIZATION and forms the Action Potential.

4. Once an action potential is initiated at the axon hillock , no further triggering event is necessary to activate the remainder of the nerve fiber. The impulse is automatically conducted throughout the neuron. in an Unmyelinated Nerve Fiber an Action Potential travels from POINT TO POINT. At the nodes of Ranvier, there are an increased number of Sodium channels present

5. CONDUCTION OF AP IN A MYELINATED NERVE FIBER : In a Myelinated Nerve Fiber an Action Potential travels by SALTATORY Conduction, which is in a jumping manner from one Node of Ranvier to the next Node of Ranvier .