Neural Tissue - Neuron Anatomy (Chapter 12)

Vocabulary flashcards covering CNS/PNS divisions, neuron structure, neuroglia, myelination, synapses, and related diseases.

Central Nervous System (CNS)

Brain and spinal cord; integrates sensory data, processes information, coordinates motor commands, and supports higher functions such as intelligence, memory, and learning.

Peripheral Nervous System (PNS)

Nervous tissue outside the CNS that delivers sensory information to the CNS and carries motor commands to effectors.

Afferent Division

Carries incoming sensory information from receptors to the CNS.

Efferent Division

Transmits motor commands from the CNS to effectors (muscles, glands, adipose tissue).

Somatic Nervous System (SNS)

Subdivision of the PNS under conscious control; controls skeletal muscles; voluntary or reflexive responses.

Autonomic Nervous System (ANS)

Subdivision of the PNS with unconscious control; regulates smooth and cardiac muscle, glands, and adipose tissue.

Sympathetic Division

Fight or flight; prepares the body for action.

Parasympathetic Division

Rest and digest; conserves energy and promotes maintenance.

Receptors

Specialized cells or neurons that detect changes in the environment and generate nerve impulses.

Special Sensory Receptors

Receptors that monitor senses such as smell, taste, vision, balance, and hearing.

Visceral Sensory Receptors

Receptors monitoring internal organs (interoceptors).

Somatic Sensory Receptors

Receptors monitoring skeletal muscles, joints, and skin surface.

Neuron

Basic functional unit of the nervous system; a nerve cell specialized to conduct electrical impulses.

Cell Body (Soma)

Largest part of the neuron containing the nucleus; site of organelles and Nissl bodies.

Dendrites

Highly branched extensions that receive information from other neurons or sensory receptors.

Axon

Long cytoplasmic process that conducts action potentials away from the cell body; may be myelinated or unmyelinated.

Axon Hillock

Triangular region where summation of potentials occurs and action potentials are generated.

Telodendria

Fine terminal branches at the end of the axon.

Axon Terminals

Endings of telodendria containing neurotransmitters; communicate with postsynaptic cells.

Presynaptic Cell

Neuron that releases neurotransmitters at a synapse.

Postsynaptic Cell

Cell that receives neurotransmitters at a synapse.

Nissl Bodies

Clusters of ribosomes and rough endoplasmic reticulum in neurons; give gray matter its appearance.

Gray Matter

Regions rich in neuron cell bodies and dendrites; appears gray due to Nissl bodies.

White Matter

Regions rich in myelinated axons; appears white due to myelin.

Nodes of Ranvier

Gaps between myelinated segments where ion exchange occurs; increase conduction speed.

Internodes

Myelinated segments of an axon between nodes.

Myelin

White, fatty sheath around axons that insulates and speeds up action potentials; produced by oligodendrocytes (CNS) or Schwann cells (PNS).

Oligodendrocytes

CNS glial cells that create myelin and provide structural support.

Schwann Cells

PNS glial cells that form the myelin sheath around peripheral axons and aid in regeneration.

Demyelination

Degradation of the myelin sheath; slows or disrupts action potential transmission, affecting sensation and movement.

Diphtheria

Bacterial disease caused by Corynebacterium diphtheriae; damages Schwann cells and can cause paralysis; preventable by vaccine.

Corynebacterium diphtheriae

Bacterium that causes diphtheria.

DTaP Vaccine

Vaccine protecting against diphtheria, tetanus, and pertussis.

Multiple Sclerosis

Most common demyelinating autoimmune disease; demyelination of axons in optic nerve, brain, and spinal cord.

Synapse

Site where a neuron communicates with another cell (neuron, muscle, or gland).

Synaptic Cleft

Gap between the presynaptic terminal and the postsynaptic membrane where neurotransmitters travel.

Presynaptic Neuron

Neuron that releases neurotransmitters into the synapse.

Postsynaptic Neuron

Neuron that receives neurotransmitters from the synapse.

Neuromuscular Junction

Synapse between a motor neuron and a skeletal muscle fiber.

Neuroglia

Supporting cells of the nervous system; outnumber neurons; protect neurons and regulate the environment.

Astrocytes

CNS glial cells that form the blood-brain barrier and regulate interstitial fluid.

Microglia

Small CNS glia that phagocytize debris and pathogens.

Ependymal Cells

Ciliated cells lining ventricles and the central canal; help produce and circulate CSF.

Satellite Cells

PNS glial cells that regulate interstitial fluid inside ganglia; similar to CNS astrocytes.

Blood-Brain Barrier

Selective barrier formed by tightly joined capillaries and astrocytes to protect CNS.

Glioblastoma Multiforme

Aggressive brain cancer arising from immature glial cells, usually astrocytes or oligodendrocytes.

Ep​ineurium

Outermost connective tissue covering a peripheral nerve.

Perineurium

Connective tissue layer that surrounds a fascicle within a peripheral nerve.

Endoneurium

Innermost connective tissue layer surrounding individual nerve fibers.