Nervous System: Neurons & Neural Pathways

Vocabulary practice flashcards covering nervous system organization, glial cell functions, axonal transport, synapse types, neurotransmitter classes, and neurotransmitter clearance mechanisms.

Central Nervous System (CNS)

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

Peripheral Nervous System (PNS)

The division of the nervous system consisting of sensory (afferent) neurons and efferent (motor) neurons.

Somatic Motor Division

The branch of the efferent peripheral nervous system that controls skeletal muscles.

Autonomic Division

The branch of the efferent peripheral nervous system controlling smooth muscle, cardiac muscle, exocrine glands, some endocrine glands, and some adipose tissue; consists of sympathetic, parasympathetic, and enteric branches.

Glial Cells

Support cells in the nervous system that provide biochemical and structural support to neurons across both the CNS and PNS.

Schwann Cells

Glial cells located in the peripheral nervous system (PNS) that form the myelin sheath around axons.

Satellite Cells

Glial cells located in the peripheral nervous system (PNS) that surround neuron cell bodies and do not form myelin.

Ganglion

A cluster or knot of neuron cell bodies situated within the peripheral nervous system (PNS).

Oligodendrocytes

Glial cells in the central nervous system (CNS) responsible for forming myelin sheaths around axons.

Astrocytes

Central nervous system glial cells that communicate via gap junctions and provide multiple structural and biochemical support functions.

Microglia

Specialized immune cells present in the central nervous system (CNS).

Ependymal Cells

Selectively permeable epithelial cells in the CNS that separate fluid compartments and act as neural stem cells.

Axonal Transport

The cellular process of moving materials along an axon, classified as either fast ($100\,\text{mm/d}$) or slow ($1\,\text{mm/d}$).

Anterograde Transport

Axonal transport that moves vesicles and organelles from the cell body toward the axon terminals.

Retrograde Transport

Axonal transport that moves cellular components from the axon terminals back toward the cell body.

Synapse

The junction where transmission of signals occurs from a presynaptic cell across a synaptic cleft to a postsynaptic cell.

Electrical Synapse

A synapse in which excitation is conducted directly between cells through gap junctions by the direct flow of ions.

Chemical Synapse

A synapse where an electrical impulse triggers synaptic vesicles to release chemical neurotransmitters across the synaptic cleft to ion channels on the receiving cell.

Amine Neurotransmitters

A class of neurotransmitters including dopamine, epinephrine, norepinephrine, serotonin, and histamine.

Amino Acid Neurotransmitters

A class of chemical neurotransmitters including glutamate, glycine, and GABA.

Purine Neurotransmitters

A group of neurotransmitter chemicals that includes adenosine.

Acetylcholinesterase

An enzyme responsible for clearing acetylcholine from the synaptic cleft through enzymatic digestion.

Neurotransmitter Clearance

The set of mechanisms used to remove neurotransmitters from the synaptic cleft, including enzymatic digestion, diffusion, reuptake by the presynaptic neuron, and uptake by nearby astrocytes.