1.1 Neurophysiology

Graded potentials

Short-distance electrical signals that vary in amplitude depending on stimulus strength.

Action potentials

Long-distance electrical signals that maintain constant strength and are triggered at the axon hillock.

Resting membrane potential

The electrical voltage across a cell membrane when the neuron is not firing, typically around -70 mV.

Ion channels

Proteins in a cell membrane that allow ions to move across, playing a crucial role in establishing resting membrane potential.

Leak channels

Ion channels that are always open and permit the passive movement of ions across the membrane.

Ligand-gated channels

Ion channels that open in response to the binding of a chemical molecule.

Mechanically gated channels

Ion channels that open in response to mechanical stimulus.

Voltage gated channels

Ion channels that open or close in response to changes in membrane potential.

Depolarization

The process of reducing membrane potential, making the inside of the cell more positive.

Hyperpolarization

The process of increasing membrane potential, making the inside of the cell more negative.

Excitatory post synaptic potential (EPSP)

A graded potential that makes the postsynaptic neuron more likely to fire an action potential.

Inhibitory post synaptic potential (IPSP)

A graded potential that makes the postsynaptic neuron less likely to fire an action potential.

Absolute refractory period

The period following an action potential during which no new action potential can be initiated.

Relative refractory period

The period following an action potential during which only a strong stimulus can initiate another action potential.

Synapse

The site of communication between two neurons or between a neuron and an effector cell.

Neurotransmitters

Chemical messengers released by neurons to communicate with other neurons, muscle fibers, and gland cells.

Saltatory conduction

The rapid propagation of action potentials along myelinated axons, jumping between nodes of Ranvier.

Continuous conduction

The slow, uninterrupted propagation of action potentials along unmyelinated axons.

Spatial summation

The accumulation of neurotransmitter effects on a postsynaptic membrane from different presynaptic inputs.

Temporal summation

The accumulation of neurotransmitter effects on a postsynaptic membrane from a single presynaptic input in rapid succession.

Na+/K+ ATPase pump

A pump that uses ATP to move sodium out of and potassium into the cell, maintaining resting membrane potential.