Electrical properties of neurons
Gilad Silberberg
Different types of neurons in the different structures of the nervous system
The nervous system: Elaborate
And vulnerable…
Structural diversity in the nervous system demonstrated with markers.
Electrical Properties of Neurons
Common Features:
• Membrane potential & ion channels
• Passive membrane properties
• Voltage-dependent (active) membranes
1.2 Examples of the rich variety of nerve cell morphologies found in humans. (Part 3)
2.2 Recording passive and active electrical signals in a nerve cell. (Part 1)
2.2 Recording passive and active electrical signals in a nerve cell. (Part 2)
2.3 Ion transporters and channels are responsible for ionic movements across membranes.
The membrane as a charge separator
2.4 Electrochemical equilibrium. (Part 1)
2.4 Electrochemical equilibrium. (Part 2)
Nernst Potential
Example for Potassium:
2.5 Membrane potential influences ion fluxes. (Part 2)
2.5 Membrane potential influences ion fluxes. (Part 3)
Different ions determine the membrane potential
Circuit representation:
Different ions determine the membrane potential
Different ions determine the membrane potential
Which ion is dominant?
The Goldman equation
Another version of the same thing:
2.7 Evidence that the resting potential is determined by K+ concentration gradient. (Part 1)
2.4 Electrochemical equilibrium. (Part 2)
Next:
Properties of ion-channels
Ion Channels
• Specialized membrane proteins that
traverse the cell membrane
• Conduct ions
• Recognize and select among specific ions
• How?
Transporters vs. Channels
Control of Ions Flux through Ion
Channels
• The flux of ions is passive, i.e., does not
require energy
• The direction of ions flux is not determined by
the channel
• The direction of ions flux is determined by the
electro-chemical driving force
Two Classes of Ion ChannelsTwo Classes of Ion Channels
• Non-gated ion channels
» Always open
» Leak channels
» Maintain the resting membrane potential
• Gated ion channels
» Open and close in response to a specific stimulus
» Transition between closed and open states = Gating
» Synaptic potentials, Action potentials
Gated Ion Channels
Type of channel Stimulus Effect
Ligand-gated Transmitter substance Directly gated synaptictransmission
Phosphorylation-gated Phosphorylation 2nd
messenger-mediatedsynaptic transmission
Voltage-gated Change in membranepotential
Generation of actionpotential
Stretch or pressure-gated Mechanical deformationof the membrane
Generation of receptorpotential in mechano-receptors
Example of the Patch-Clamp technique
Summary
• Ion channels are:
• Specialized membrane proteins
• Conduct ions
• Recognize and select among specific ions
• Subdivided into two classes: non-gated and
gated channel