Nervous Tissue Flashcards P2

50 vocabulary flashcards to review key terms and definitions related to nervous tissue, neuroglia, neuron anatomy, and central/peripheral nervous system organization, including cerebral and cerebellar cortex layers.

Schwann (neurolemmocyte)

Neuroglial cells that myelinate axons of the Peripheral Nervous System (PNS).

Node of Ranvier

A gap in the insulating myelin sheath of axons that facilitates the rapid conduction of nerve impulses.

Neurolemma (sheath of Schwann)

The outermost nucleated cytoplasmic layer of the Schwann cell that encloses the myelin sheath.

Satellite Cells (PNS)

Neuroglial cells that surround neuronal cell bodies in the Peripheral Nervous System, insulating, nourishing, and regulating their microenvironment.

Myelin Sheath

An insulating layer around an axon, formed by the overlapping inner layers of the neurolemmocyte (Schwann cell) plasma membrane.

Unmyelinated Axons

Axons that are enveloped by a Schwann cell but do not have multiple myelin sheath wraps around each axon.

Dendrites

Branching processes of a neuron that receive input or nerve impulses.

Axon

A long, slender projection of a neuron that conducts nerve impulses away from the cell body.

Cell Body (Neuron)

The main part of a neuron containing the nucleus, nucleolus, and Nissl bodies; also known as the soma.

Nissl bodies (Chromatophilic substances)

Rough endoplasmic reticulum and free ribosomes found in the neuron cell body, involved in protein synthesis.

Axon Collateral

A side branch extending from an axon.

Axon Hillock

A cone-shaped region of the neuron cell body from which the axon originates.

Neurofibril

Intermediate filaments found within a neuron that provide structural support.

Axoplasm

The cytoplasm found within an axon.

Axolemma

The plasma membrane that surrounds an axon.

Axon Terminal

The distal end of an axon, specialized for transmitting signals across a synapse.

Synaptic End Bulb

A swollen tip at the end of an axon terminal that contains synaptic vesicles.

Terminal Arborizations

Numerous fine branches at the very end of an axon.

Terminal Boutons

The enlarged ends of axon terminal branches, equivalent to synaptic end bulbs.

Ganglion

A cluster of neuron cell bodies located outside the Central Nervous System (CNS).

Sensory Ganglion

A ganglion containing primarily pseudounipolar neurons, involved in sensory pathways.

Autonomic Ganglion

A ganglion containing primarily multipolar neurons, involved in autonomic nervous system functions.

Pseudounipolar Neurons

Neurons with a single process that divides into two, typically found in sensory ganglia.

Multipolar Neurons

Neurons with one axon and multiple dendrites, commonly found throughout the brain, spinal cord, and autonomic ganglia.

Oligodendrocyte

A type of neuroglial cell in the CNS that myelinates CNS axons and may myelinate more than one axon.

Astrocyte (CNS)

Star-shaped neuroglial cells in the CNS that control the ionic environment, form scar tissue, and contribute to the blood-brain barrier.

Blood-Brain Barrier

A highly selective semipermeable border of endothelial cells and astrocytes that protects the brain.

Microglia

Phagocytic neuroglial cells in the CNS that act as the immune system of the brain and spinal cord.

Ependymal Cells

Neuroglial cells that line the CNS cavities (ventricles) and form the choroid plexus.

Choroid Plexus

A network of ependymal cells and capillaries that produces cerebrospinal fluid (CSF) within the ventricles of the brain.

Central Nervous System (CNS)

The part of the nervous system consisting of the brain and spinal cord.

Peripheral Nervous System (PNS)

All nervous tissue located outside the Central Nervous System.

Gray Matter

Regions of the CNS primarily containing neuron cell bodies, dendrites, unmyelinated axons, and neuroglia.

White Matter

Regions of the CNS primarily containing myelinated axons, giving it a lighter appearance.

Spinal Cord (Structure)

A component of the CNS which typically has gray matter internally and white matter externally.

Brain (Structure)

A complex organ of the CNS, characterized by an outer shell of gray matter (cortex), deep white matter, and additional deeper gray matter.

Cerebral Cortex

The outer shell of gray matter in the cerebral hemispheres, typically organized into 6 layers.

Molecular Layer (Cerebral Cortex)

The outermost layer of the cerebral cortex, consisting mainly of axons and dendrites (cell processes).

External Granular Layer (Cerebral Cortex)

A layer of the cerebral cortex containing densely packed stellate cells and small pyramidal cells.

External Pyramidal Layer (Cerebral Cortex)

A layer of the cerebral cortex containing loosely packed stellate cells and medium pyramidal cells.

Internal Granular Layer (Cerebral Cortex)

A layer of the cerebral cortex characterized by densely packed stellate cells only.

Internal Pyramidal Layer (Cerebral Cortex)

A layer of the cerebral cortex containing large pyramidal cells, including the Giant Pyramidal cells of Betz.

Multiform Layer (Cerebral Cortex)

The innermost (Layer VI) layer of the cerebral cortex, with multiple sized pyramidal cells and loosely packed stellate cells.

Pyramidal Neurons

Conical-shaped neurons found in various layers of the cerebral cortex, characterized by a triangular cell body.

Stellate Cells

Star-shaped neurons found in several layers of the cerebral cortex, particularly in granular layers.

Giant Pyramidal Cells of Betz

Very large pyramidal neurons specifically found in the internal pyramidal layer (Layer V) of the cerebral cortex.

Cerebellar Cortex

The outer gray matter of the cerebellum, organized into 3 distinct layers.

Molecular Layer (Cerebellar Cortex)

The outermost layer of the cerebellar cortex, containing dendrites of Purkinje cells and axons of granule cells.

Purkinje Cells

Large, flask-shaped neurons that form a distinct single layer within the cerebellar cortex, critical for motor coordination.

Granular Layer (Cerebellar Cortex)

The innermost layer of the cerebellar cortex, beneath the Purkinje cell layer, containing densely packed granule cells.