The part of a neuron that houses the nucleus and most other organelles

Cell Body

Numerous short, highly branched extensions of a neuron that receive signals from other neurons

Dendrites

Typically long extension, or process, of a neuron that carries nerve impulses away from the cell body toward target cells

Axon

Junction where a neuron communicates with another cell across a narrow gap via a neurotransmitter or an electrical coupling

Synapse

A molecule that is released from the synaptic terminal of a neuron at a chemical synapse, diffuses across the synaptic cleft, and binds to the postsynaptic cell, triggering a response

Neurotransmitter

Cells of the nervous system that support, regulate, and augment the functions of neurons

Glia

A nerve cell that receives information from the internal or external environment and transmits signals to the central nervous system

Sensory Neuron

An association neuron; a nerve cell within the central nervous system that forms synapses with sensory and/or motor neurons and integrates sensory input and motor output

Interneuron

A nerve cell that transmits signals from the brain or spinal cord to muscles or glands

Motor neuron

The portion of the nervous system where signal integration occurs; in vertebrate animals, the brain and spinal cord

Central Nervous System

The sensory and motor neurons that connect to the central nervous system

Peripheral Nervous System

A fiber composed primarily of the bundled axons of neurons

Nerve

The difference in electrical charge (voltage) across a cell's plasma membrane due to the differential distribution of ions.

Membrane potential

Characteristic of a nonconducting excitable cell, with the inside of the cell more negative than the outside

Resting potential

Transport protein in the plasma membrane of animal cells that actively transports sodium out of the cell and potassium into the cell

Sodium-potassium pump

Transmembrane protein channel that allows a specific ion to diffuse across the membrane down its concentration or electrochemical gradient

Ion Channel

The magnitude of a cell's membrane voltage at equilibrium, calculated using the Nernst equation

Equilibrium Potential

The opening or closing of a channel for a specific ion

Gated ion channel

A change in a cell's membrane potential such that the inside of the membrane becomes more negative relative to the outside. (Reduces the chance that a neuron will transmit a nerve impulse)

Hyperpolarization

A change in a cell's membrane potential such that the inside of the membrane is made less negative relative to the outside.

Depolarization

In a neuron, a shift in the membrane potential that has an amplitude proportional to signal strength and the decays as it spreads

Graded potential

An electrical signal that travels along the membrane of a neuron or other excitable cell as a nongraded (all-or-none) depolarization

Action Potential

A specialized ion channel that opens and closes in a response to changes in a membrane potential

Voltage-gated ion channel

The potential that an excitable cell membrane must reach for an action potential to be initiated

Threshold

The short time immediately after an action potential in which the neuron cannot respond to another stimulus, owing to the inactivation of voltage-gated sodium channels

Refractory period

Wrapped around the axon of a neuron, an insulating coat of cell membranes from Schwann cells or oligodendrocytes. It is interrupted by nodes of Ranvier, where action potentials are generated

Myelin Sheath

A type of glial cell that forms insulating myelin sheaths around the axons of neurons in the central nervous system

Oligodendrocyte

A type of glial cell that forms insulating myelin sheaths around the axons of neurons in the peripheral nervous system

Schwann Cell

Gap in the myelin sheath of certain axons where an action potential may be generated

Node of Ranvier

Rapid transmission of a nerve impulse along an axon, resulting from the action potential jumping from one node of Ranvier to another, skipping the myelin sheathed regions of membranes

Salatory Conduction

A transmembrane protein containing a pore that opens or closes as it changes shape in response to a signaling molecule, allowing or blocking the flow of specific ions

Ligand gated ion channel

An electrical change (depolarization) in the membrane of a postsynaptic cell caused by the binding of an excitatory neurotransmitter from a presynaptic cell to a postsynaptic receptor, makes it more likely for a postsynaptic cell to generate an action pot

Excitatory postsynaptic potential

An electrical change (usually hyperpolarization) in the membrane of a postsynaptic neuron caused by the binding of an inhibitory neurotransmitter from a presynaptic cell to a postsynaptic receptor; makes it more difficult for a postsynaptic neuron to gene

Inhibitory postsynaptic potential

A phenomenon of neural integration in which the membrane potential of the postsynaptic cell in a chemical synapse is determined by the combined effect of EPSPs or IPSPs produced in rapid succession

Temporal Summation

A phenomenon of neural integration in which the membrane potential of the postsynaptic cell is determined by the combined effect of EPSPs or IPSPs produced nearly simultaneously by different synapses

Spatial Summation

One of the most common neurotransmitters; functions by binding to receptors and altering the permeability of the postsynaptic membrane to specific ions, either depolorizing or hyperpolorizing the membrane

Acetylcholine

An amino acid that functions as a neurotransmitter in the central nervous system

Glutamate

An amino acid that functions as a neurotransmitter in the central nervous system of vertebrates

Gamma-aminobutyric acid

A neurotransmitter derived from an amino acid

Biogenic Amine

Catecholamine that is chemically and functionally similar to epinephrine and that acts as a hormone or neurotransmitter

Norepinephrine

A neurotransmitter that is a catecholamine, like epinephrine and norepinephrine

Dopamine

A neurotransmitter, synthesized from the amino acid tryptophan, that functions in the central nervous system

Serotonin

Any of several hormones produced in the brane and anterior pituitary that inhibit pain perception

Endorphins