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Nervous System and Spinal Cord


action potential

rapid change in membrane potential due to changes in the flux of potassium and sodium ions inside and outside the cell

afferent neuron

neuron that carries sensory information from sensory organs (e.g., eyes, ears, and skin) to the central nervous system

anaxonic neuron

neuron that has multiple projections, none of which are easily identifiable as the axon


star-shaped glial cell in the CNS that supports neurons by connecting them to nutrient supplies and by repairing nervous tissue after injury


extension from the neuronal cell body that transmits the signal to receiving cells

axon terminal

end of an axon where nerve impulses are transmitted to the next cell

bipolar neuron

neuron with a cell body with one dendrite and one axon extending off of it in opposite directions from each end

central nervous system (CNS)

division of the nervous system that consists of the brain and spinal cord


extension from the neuronal cell body that receives input from other cells

efferent neuron

neuron that carries motor information from the CNS to effector organs, including muscles and glands

enteric nervous system

part of the autonomic nervous system, a division of the PNS, that controls local blood flow, movement, and mucus secretions

ependymal cell

type of glial cell, in the CNS, that lines the spinal cord and ventricles of the brain as well as produces cerebrospinal fluid


bundle of neurons in a nerve fiber that belongs to the peripheral nervous system


mass of tissue that contains several cell bodies

gray matter

area of the spinal cord consisting of cell bodies that have no myelin covering, appears gray, and is surrounded by white matter


neuron that relays information between an afferent (sensory) neuron and efferent (motor) neuron


a glial cell that mediates immune responses in the CNS

multipolar neuron

neuron that contains a single axon and many dendrites that extend from the cell body

myelin sheath

lipid-rich material that wraps around the axon and helps impulses travel through neurons


cells that support and protect neurons


cell in the nervous tissue that transmits electrical and chemical signals throughout the body


chemical that binds to receptors and excites or inhibits postsynaptic cells

node of Ranvier

gap between myelin sheaths where the axon is uncovered


glial cell that generates myelin, which wraps around axons in the CNS

peripheral nervous system (PNS)

division of the nervous system that includes all nerves extending from the brain and spinal cord

satellite cell

glial cell in the PNS that surrounds the cell bodies of neurons in sensory, sympathetic, and parasympathetic ganglia

Schwann cell

glial cell that provides myelination to axons in the PNS


bundle of neurons in a nerve fiber that belongs to the central nervous system

unipolar neuron

sensory neuron that has a single, long axon extending from the cell body

white matter

area of the spinal cord made up of axons covered with myelin and surrounding and connecting areas of gray matter