The Nervous System: Neurons, Glial Cells, and Synapses

Comprehensive vocabulary flashcards covering the structural organization of the nervous system, cellular components, glial cell classes, synaptic anatomy, and physiological mechanisms.

Sensory components

The functional parts of the nervous system that detect environmental changes.

Integrative components

The parts of the nervous system that process incoming sensory data coupled with information stored in memory.

Motor components

The parts of the nervous system that provide a response to processed information.

Neuron

A nerve cell that transmits nerve impulses and joins with other cells via synapses.

Glial cells (neuroglia)

Non-neuronal cells that provide service to neurons and their environment, outnumbering neurons roughly 10-fold in the human brain.

Dendrites

Highly branched neuronal processes that conduct impulses toward the cell body and provide large surface area for receiving information from other neurons.

Axon

A single neuronal process that conducts impulses away from the cell body.

Nerve fiber

An axon together with its myelin covering, if present.

Neurilemma (sheath of Schwann)

The outermost myelin layer, consistent with the Schwann cell, that surrounds the axolemma in a myelinated peripheral nerve fiber.

Axolemma

The plasma membrane that covers the axon.

Telodendritic zone

The terminal branching zone of an axon.

Bipolar neuron

A neuron with one axon and one dendrite extending from the cell body, found in the retina of the eye and the olfactory region of the nose.

Multipolar neuron

A neuron with many branching dendrites and one axon extending from the cell body; the most common neuron type in the central nervous system.

Nucleus (neuroanatomy)

A group of nerve cell bodies located within the brain or spinal cord (CNS).

Ganglion

A group of nerve cell bodies located outside the brain or spinal cord (PNS).

Tract (fasciculus)

A bundle of parallel neuron fibers located within the brain or spinal cord (CNS).

Nerve

A bundle of neuron fibers located outside the brain or spinal cord (PNS).

Synapse

The site of communication providing continuity between neurons, transmitting impulses via chemical means across an unjoined space.

Synaptic gap (synaptic cleft)

The fluid-filled physical space between presynaptic and postsynaptic membranes through which neurotransmitters travel.

Terminal bulb

A swelling at the end of an axon that fits into an indentation of the postsynaptic cell membrane.

Synaptic vesicles

Structures contained within the terminal bulb of an axon that store neurotransmitters.

Facilitation

A synaptic characteristic in which repeated impulses allow for easier subsequent transmission across the synapse.

Fatigability (synaptic)

A synaptic property characterized by greater susceptibility to exhaustion than the neuron itself, allowing repetitive impulses to fade.

Oligodendrocytes

Glial cells in the central nervous system that possess several cytoplasmic extensions, each forming a myelin sheath around different axon locations.

Schwann cells

Glial cells responsible for myelin sheath formation in the peripheral nervous system, with one cell wrapping around one axon.

Astrocytes

The most numerous star-shaped glial cells that provide structural support, supply nourishment from blood vessels, and release glutamate in response to stimulation.

Ependymal cells

Glial cells that line the brain ventricles and the central canal of the spinal cord, joining with capillaries to form the choroid plexus for cerebrospinal fluid production.

Microglia

Phagocytic glial cells that enter the CNS from blood vessels and multiply during inflammatory processes or neuronal injury.

Myelin

A white lipid substance (sphingomyelin) forming an insulating sheath around nerve fibers that increases impulse conduction speed.

Nodes of Ranvier

Regularly spaced myelin-free gaps along a nerve fiber where the axolemma is exposed to extracellular fluid, allowing electrolyte exchange and depolarization.

Saltatory conduction

The rapid transmission of a nerve impulse where the depolarizing action potential jumps from one Node of Ranvier to the next along myelinated segments.

Central nervous system (CNS)

The major division of the nervous system consisting exclusively of the brain and spinal cord.

Peripheral nervous system (PNS)

The division of the nervous system comprising cranial nerves and spinal nerves located outside the brain and spinal cord.

Autonomic nervous system (ANS)

An involuntary division of the nervous system possessing central and peripheral components, subdivided into sympathetic, parasympathetic, and enteric systems.

Sympathetic nervous system

A subdivision of the autonomic nervous system responsible for initiating fight-or-flight responses.

Parasympathetic nervous system

A subdivision of the autonomic nervous system responsible for regulating rest-and-digest functions.

Enteric nervous system

A subdivision of the autonomic nervous system dedicated to governing gut activity.