NEUR101 Neurophysiology

Neuron

The basic building block of the nervous system responsible for transmitting information.

Ion

An atom or molecule that has acquired an electric charge by gaining or losing one or more electrons.

Cation

Positively charged ions, e.g., Na+ or K+

Anion

Negatively charged ions, e.g., Cl-

Concentration Gradient

The force that causes ions to move from areas of high concentration to areas of low concentration.

Electrostatic Pressure

A potential gradient where like charges repel and opposite charges attract.

Membrane Potential

The electrical potential difference across the cell membrane, typically ranging from -50 to -80 mV.

Equilibrium Potential

The membrane potential at which the net flow of a particular ion across the membrane is zero.

Nernst Equation

An equation used to calculate the equilibrium potential for an ion based on its concentration inside and outside the cell.

Sodium-Potassium Pump

An active transport mechanism that pumps Na+ out of the cell and K+ into the cell, crucial for maintaining resting potential.

Action Potential

A brief, large change in membrane polarity triggered at the axon hillock and propagated along the axon.

Depolarization

A decrease in resting membrane potential, making the inside of the cell less negative.

Hyperpolarization

An increase in resting membrane potential, making the inside of the cell more negative.

Refractory Period

The period during which a neuron is unable to fire another action potential.

Excitatory Postsynaptic Potential (EPSP)

A small depolarization of the postsynaptic cell that brings it closer to the action potential threshold.

Inhibitory Postsynaptic Potential (IPSP)

A small hyperpolarization of the postsynaptic cell, making it less likely to fire an action potential.

Synapse

The junction where communication occurs between two neurons, involving neurotransmitter release.

Ionotropic Receptors

Ligand-gated ion channels that change postsynaptic polarity upon ligand binding.

Metabotropic Receptors

Receptors that activate internal cell processes via G proteins but do not open ion channels directly.

Degradation

The breakdown of neurotransmitters by enzymes, which recycles their components.

Electrical Synapse

A type of synapse that allows for direct electrical communication between neurons with no delay.

Chemical Synapse

A type of synapse that uses neurotransmitters to communicate between neurons.

Calcium Ions (Ca2+)

Critical ions involved in the neurotransmitter release process at the presynaptic terminal.

Second Messengers

Molecules like cyclic AMP involved in signal transduction that can activate protein kinases.

Selectivity Filter

A structure in ion channels that determines the specific ions that can pass through.