Neuronal Physiology Prepared by: Dr A. Riasi Isfahan University of Technology
Every cell in animal body displays a membrane potential. Introduction
Neurons and muscles are excitable cells and can change their membrane potential. Introduction
Terminology and methodology: Polarization Depolarization Repolarization Hyperpolarization Introduction
How these information are prepared? There are two techniques for this kind of studies: Introduction Using microelectrodes Patch clamping
Introduction
A patch pipette on a cultured neuron
Introduction The water-soluble ion have to penetrate the plasma membrane using the specific channels.
Introduction Leak channels (non-gated channels) Gated channels Voltage-gated channels Chemically gated channels (ligand channels) Mechanically channels
Two basic forms of electrical signals
We can describe the passive movement of electrical depolarizing by Ohm’s Law: ∆V m = ∆ I × R or ∆ I = ∆Vm × g Two basic forms of electrical signals
Postsynaptic potentials Receptor potentials End-plate potentials Pacemaker potentials Slow-wave potential The graded potentials are critically important to neurnal function for example: Two basic forms of electrical signals
Propagation of an action potential Once initiated, action potentials are conducted over the surface of an axon by: Contiguous conduction Saltatory conduction
Propagation of an action potential
Absolute and relative refractory periods The refractory period ensures unidirectional propagation of the action potential and limits the frequency of action potentials.
Absolute and relative refractory periods
Action potentials occur in all-or- none fashion
Myelination fiber
Myelin as insulator layer
Saltatory conduction
Pre and post synaptic neuron
Synapse structure
Excitatory Synapse from the Central Nervous System (TEM x27,360). This image is copyright Dennis Kunkel at used without permissionwww.DennisKunkel.com Synapse structure
Post synaptic potentials
Grand post-synaptic potential
Pre-synaptic inhibition
Convergence and divergence