The Nervous System Vocabulary

Action Potential

Sequence of electrical changes occurring when the threshold of a stimulus is exceeded

Autonomic Nervous System

The division of the PNS that functions involuntarily; connects CNS to organs and glands


Neuron process that carries impulses away from the nerve cell body

Central Nervous System

The brain and spinal cord are the principal components


Largest part of the brain; provides higher mental functions and has left and right hemispheres


Nerve fibers that carry electrical signals toward cell bodies; receptive end of nerve cell


The membranes that cover the brain and spinal cord

Motor/Efferent Nerves

Nerves that carry impulses to muscles, organs, and glands from the CNS

Myelin Sheath

Tight coil of wrapped fatty membranes that protects and insulates the fibers and increases the transmission rate of nerve impulses in axons outside the CNS


Cordlike bundle of nerve fivers outside the CNS; held together by connective tissue

Nerve Impulse

Propagation of action potentials along a nerve fiber


Chemical secreted by an axon at a synapse. Theses may stimulate or inhibit neurons


Cells that specialized to transmit throughout the body (nerve cells)

Parasympathetic Nervous System

Part of autonomic nervous system that is active under ordinary "restful" conditions

Peripheral Nervous System

Division of nervous system that connects the outline parts of the body with the CNS

Schwann Cells

Type of neuroglia cell that forms myelin around nerve fibers/axons within PNS

Sensory/Afferent Nerves

nerve cells that carry impulses toward the CNS

Somatic Nervous System

The voluntary part of the peripheral nervous system; consist of spinal and cranial nerves that connects CNS to skeletal muscles

Sympathetic Nervous System

Division of autonomic nervous system that prepares our body for emergency situations


Junction of communication between axon of one neuron and dendrite of another neuron of another neuron or an effector

Synaptic Cleft

The fluid-filled space at a synapse between neurons