Neurons and Glial Cells – NS1 Introduction Extra Slides

Vocabulary flashcards covering neuron anatomy, glial cell functions, and the stages of the action potential from the lecture notes.

Neuron

A specialized cell that transmits nerve impulses through electrochemical signals.

Cell Body (Soma)

The metabolic center of a neuron that houses the nucleus and most organelles.

Dendrite

Branched neuronal process that receives incoming signals and generates graded potentials.

Axon

A long neuronal projection that conducts action potentials away from the cell body.

Axon Hillock

Cone-shaped region of the cell body where action potentials are initiated.

Synaptic Terminals (Axon Terminals)

Distal endings of an axon where neurotransmitters are released to communicate with other cells.

Schwann Cell

Peripheral nervous system (PNS) glial cell that myelinates or insulates PNS axons.

Myelin Sheath

Multilayered lipid-rich covering formed by glia that increases the speed of action potential conduction.

Unmyelinated Axon

Nerve fiber lacking a myelin sheath; still supported or enveloped by Schwann cells in the PNS.

Oligodendrocyte

Central nervous system (CNS) glial cell that extends multiple processes to myelinate several axons.

Myelination

The process by which Schwann cells or oligodendrocytes wrap axons with myelin, boosting conduction velocity.

Graded Potential

A small, localized change in membrane potential on dendrites or the soma that can summate to reach threshold.

Action Potential

A rapid, all-or-none electrical impulse that propagates along an axon once threshold is reached.

Depolarization

Phase of the action potential where voltage-gated Na⁺ channels open, causing Na⁺ influx and membrane voltage to rise toward +30 mV.

Repolarization

Phase of the action potential where Na⁺ channels close and voltage-gated K⁺ channels open, leading to K⁺ efflux and return toward resting potential.

Hyperpolarization (Undershoot)

After-potential phase in which continued K⁺ efflux makes the membrane more negative than the resting level before channels reset.

Voltage-Gated Na⁺ Channel

Membrane protein that opens with threshold depolarization, allowing sodium ions to rush into the neuron.

Voltage-Gated K⁺ Channel

Membrane protein that opens during repolarization, allowing potassium ions to exit the neuron.