Nervous System: Neurons, Action Potentials, and System Organization (Vocabulary)

Vocabulary flashcards covering neurons, action potentials, CNS vs PNS organization, autonomic vs somatic divisions, myelination and related structures, and autoimmune demyelination.

Neuron

Nerve cell; the basic unit of the nervous system that transmits electrical signals (action potentials) and communicates with other neurons and effectors.

Action potential

Electrical impulse that travels along a neuron to convey information.

Central nervous system (CNS)

Brain and spinal cord; the part of the nervous system where processing occurs.

Peripheral nervous system (PNS)

All nerves outside the CNS; detects sensory information and carries motor commands to muscles, glands, and other tissues.

Cranial nerves

Peripheral nerves that originate from the brain; not part of the CNS.

Somatic nervous system

Subdivision of the PNS that controls voluntary movements and conveys sensory information under conscious control.

Autonomic nervous system

Subdivision of the PNS that regulates involuntary functions; subdivides into sympathetic and parasympathetic divisions.

Sympathetic division

Autonomic division responsible for fight-or-flight responses (e.g., increased heart rate); prepares body for action.

Parasympathetic division

Autonomic division that promotes rest-and-digest activities (e.g., digestion, energy storage).

Myelination

Process of wrapping axons with myelin sheaths to speed up electrical conduction.

Oligodendrocytes

CNS glial cells that form myelin around axons.

Internodes

Myelinated segments of an axon between two nodes of Ranvier.

White matter

Brain and spinal cord tissue dominated by myelinated axons; appears white.

Gray matter

Regions containing neuronal cell bodies and dendrites; less myelinated.

Corpus callosum

Major white-matter tract connecting the two cerebral hemispheres to enable interhemispheric communication.

Dendrites

Neuron processes that receive signals from other neurons.

Axon

Long neuronal process that transmits outgoing signals to other neurons or targets.

Synapse

Junction where one neuron communicates with another, typically at dendrite or cell body regions.

Demyelination

Loss or damage of myelin around axons, slowing or disrupting electrical conduction.

Autoimmune

Condition in which the body's immune system attacks its own tissues.

Nodes of Ranvier

Gaps between myelin segments where ion exchange occurs, enabling saltatory conduction.