ACTION POTENTIAL

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Presentation Description

The mechanism of action potential through a neuron is discussed in this presentation.

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Presentation Transcript

ACTION POTENTIAL IN A NEURON : 

ACTION POTENTIAL IN A NEURON Presented To: MISS ZUNAIRA NAWAZ Presented By: MUHAMMAD ARSLAN ABDULLAH MUHAMMAD REHAN AZMAT MUHAMMAD USMAN SHAFIQ-UR-REHMAN SAADULLAH Department Of Pharmacy The University Of Lahore

Outline : 

Outline Definition Action potential through a Neuron Stages of Action potential Propagation of Action potential Myelinated Neurons Un-myelinated neurons Conduction Velocity Refractory period ABSOLUTE - Refractory period RELATIVE - Refractory period All or None Principle Summation ACTION POTENTIAL

Definition : 

Definition “An action potential (also known as a nerve impulse or a spike potential) is a self-regenerating wave of electrochemical activity (in response to stimuli) that allows excitable cells (such as muscle and nerve cells) to carry a signal over a distance.” ACTION POTENTIAL

Action potential through a Neuron : 

Action potential through a Neuron

Stages of Action potential : 

Stages of Action potential 3- Stages

Stages of Action potential : 

Stages of Action potential Resting stage inside –ve membrane. Outside +ve membrane. Na+ and K+ Channels are close. Membrane is at rest. This is resting membrane potential. ACTION POTENTIAL

Stages of Action potential : 

Stages of Action potential Depolarization Threshold stimulus (about -60 to -55mV) excite the Na-channels. Na+ Channels Open. Influx of Na+ Stats. Na+ ions Rush in. Inside +ve membrane. Outside -ve membrane. Membrane potential rises from -70mV to +40mV Action Potential or nerve impulse is then generated. ACTION POTENTIAL

Stages of Action potential : 

Stages of Action potential Repolarization Then Na+ Channels Close. At the same time K+ Channels Open Efflux of K+ Stats. Inside again -ve membrane. And Outside +ve membrane. Membrane potential fall to -80mV (called Undershoot) Then Na-K-Pumps Work actively using ATP, to retain the Equilibrium. Sending 3 Na+ out and 2 K+ in to the cell. And restore the mebrane potential of -70mV ACTION POTENTIAL

Stages of Action potential Graphical View : 

Stages of Action potential Graphical View

Summary : 

Summary A Short Video clip Mechanism.

Slide 12: 

ACTION POTENTIAL

NOW!How Action potential Propagate? Thruogh : 

NOW!How Action potential Propagate? Thruogh Myelinated Neurons Un-myelinated neurons

Propagation of Action potential Through Myelinated Neurons : 

Propagation of Action potential Through Myelinated Neurons Through Nodes of ren vier. It is a jumping movement called Saltatory movement. ACTION POTENTIAL

Propagation of Action potential Through Un-Myelinated Neurons : 

Propagation of Action potential Through Un-Myelinated Neurons through each and every part of the membrane. That’s why it is called Contineuous conduction. ACTION POTENTIAL

Summary : 

Summary A Short Video clip Mechanism.

Slide 17: 

ACTION POTENTIAL

Refractory period : 

Refractory period ABSOLUTE - Refractory period RELATIVE - Refractory period

ABSOLUTE - Refractory period : 

ABSOLUTE - Refractory period During an action potential, a second stimulus will not produce a second action potential (no matter how strong that stimulus is) ACTION POTENTIAL

ABSOLUTE - Refractory period : 

ABSOLUTE - Refractory period During an action potential, a second stimulus will not produce a second action potential (no matter how strong that stimulus is) ACTION POTENTIAL

RELATIVE - Refractory period : 

RELATIVE - Refractory period Another action potential can be produced, but only if the stimulus is greater than the threshold stimulus ACTION POTENTIAL

All or None Principle : 

All or None Principle A law stating that - action potentials occur maximally or not at all ACTION POTENTIAL

Thank You! : 

Thank You! THE END ACTION POTENTIAL