Nervous Tissue and Organization of the Nervous System

These flashcards cover key terms and definitions related to nervous tissue and the organization of the nervous system.

Central Nervous System (CNS)

Includes the brain and spinal cord.

Peripheral Nervous System (PNS)

Includes cranial nerves, spinal nerves, and ganglia.

Sensory Nervous System

Receives sensory information from receptors in the PNS and transmits it to the CNS.

Motor Nervous System

Sends impulses from the CNS through the PNS to muscles and glands.

Neurons

Electrically excitable cells that initiate, transmit, and receive nerve impulses.

Glial Cells

Nonexcitable cells that support and protect neurons.

Myelination

The process of wrapping an axon with a myelin sheath to electrically insulate it.

Astrocytes

The most abundant glial cells in the CNS, involved in forming the blood-brain barrier and regulating tissue fluid composition.

Ependymal Cells

Ciliated cuboidal epithelial cells that line the ventricles of the brain and central canal of the spinal cord, producing cerebrospinal fluid.

Axon Hillock

The region where the axon connects to the cell body.

Synapse

A specialized junction between two neurons, or between a neuron and a muscle or gland cell.

Saltatory Conduction

Impulse conduction that occurs when a myelinated neuron propagates impulses by jumping between neurofibril nodes.

Neurolemmocyte (Schwann Cell)

A glial cell in the PNS that forms myelin around PNS axons.

Neuronal Circuit

Patterns of neurons grouped based upon function.

Converging Circuit

Impulses come together to a single postsynaptic neuron.

Diverging Circuit

Impulses spread from one presynaptic neuron to many postsynaptic neurons.

Reverberating Circuit

Cyclical stimulation of the circuit.

Parallel-after-discharge Circuit

Several neurons process the information simultaneously.

Epineurium

The connective tissue that surrounds the entire nerve.

Perineurium

The connective tissue that surrounds each fascicle of axons.

Endoneurium

The connective tissue that surrounds each individual axon.