Neurophysiology: Neural Structure, Membrane Potentials, and Gated Channels

Comprehensive vocabulary flashcards covering neural connective tissue layers, electrical gradients, membrane resting potential mechanisms, gated ion channels, and graded potentials.

Afferent

Carries nerve signals towards the central nervous system (CNS).

Efferent

Carries nerve signals away from the central nervous system (CNS).

Nerves

Bundles of axons surrounded by different types of connective tissue.

Endoneurium

Connective tissue layer that surrounds individual axons.

Perineurium

Connective tissue that bundles axons into fascicles.

Epineurium

Connective tissue that provides a tough, outer protective layer around a nerve.

Voltage

The separation of charged particles, acting as a driving force.

Current

The flow or movement of charged particles.

Resistance

The electrical property that opposes the flow or movement of charged particles.

Chemical Concentration Gradient

An uneven distribution of molecules across the plasma membrane.

Electrical Gradient

An uneven distribution of charge across the plasma membrane.

Electrochemical Gradient

The combined chemical and electrical gradient that determines the direction in which ions will flow.

Resting Membrane Potential (RMP)

The electrical potential across the plasma membrane of a cell at rest, typically around $-70\,\text{mV}$, where the inside of the cell is more negative than the outside.

$Na^+/K^+$ Pump

An active transport pump that uses ATP to establish chemical gradients by moving $3\,Na^+$ out of the cell and $2\,K^+$ into the cell.

Potassium ($K^+$) Leak vs. Sodium ($Na^+$) Leak

The passive diffusion of ions across resting channels, where $Na^+$ leak is smaller than $K^+$ leak.

Mechanically Gated Channels

Ion channels that open due to a physical force that deforms the cell membrane.

Ligand (Chemically) Gated Channels

Ion channels that open when a neurotransmitter or another specific chemical binds to them.

Voltage-Gated Channels

Ion channels that open when the membrane voltage changes to a critical level.

Depolarization

A change in membrane potential where the inside of the cell becomes more positive, moving membrane voltage closer to threshold (excitatory).

Hyperpolarization

A change in membrane potential where the inside of the cell becomes more negative, moving membrane voltage away from threshold (inhibitory).

Graded Potentials

Short-lived changes in membrane potential that can occur anywhere in a cell (especially dendrites and soma), vary in size, can depolarize or hyperpolarize the membrane, and weaken as ions diffuse away from the origin.