Overview of the Nervous System and Nervous Tissue

Vocabulary flashcards covering key terms and definitions from the lecture on the nervous system and nervous tissue.

Nervous System

Master controlling and communicating system of the body that uses rapid electrical and chemical signals.

Sensory Input

Information gathered by sensory receptors about internal and external changes.

Integration

Processing and interpretation of sensory input within the CNS.

Motor Output

Activation of effector organs (muscles or glands) that produces a response.

Central Nervous System (CNS)

Brain and spinal cord; the integration and control center of the body.

Peripheral Nervous System (PNS)

Portion of the nervous system outside the CNS; includes nerves and ganglia.

Afferent (Sensory) Division

PNS subdivision that conveys impulses from receptors to the CNS.

Efferent (Motor) Division

PNS subdivision that transmits impulses from the CNS to effector organs.

Somatic Nervous System

Voluntary motor division that conducts impulses from the CNS to skeletal muscles.

Autonomic Nervous System (ANS)

Involuntary motor division that regulates cardiac muscle, smooth muscle, and glands.

Sympathetic Division

ANS subdivision that mobilizes body systems during activity (fight or flight).

Parasympathetic Division

ANS subdivision that conserves energy and promotes housekeeping during rest (rest and digest).

Neuroglia (Glial Cells)

Supporting cells of nervous tissue that aid neurons.

Astrocytes

Most abundant CNS glia; support neurons, regulate exchanges with capillaries, and participate in information processing.

Microglial Cells

Small CNS glia that monitor neurons and act as phagocytes for debris and microorganisms.

Ependymal Cells

Ciliated CNS glia lining brain ventricles and spinal canal; circulate cerebrospinal fluid.

Oligodendrocytes

CNS glia whose processes form myelin sheaths around multiple axons.

Satellite Cells

PNS glia that surround neuron cell bodies in ganglia; function like astrocytes.

Schwann Cells

PNS glia that form myelin sheaths around peripheral axons and aid regeneration.

Neuron

Excitable cell that transmits electrical signals; structural unit of the nervous system.

Soma (Perikaryon)

Neuron cell body; biosynthetic center containing nucleus and organelles.

Dendrites

Short, branched neuron processes that receive signals and convey graded potentials to the soma.

Axon

Single neuron process that generates and conducts nerve impulses away from the soma.

Axon Hillock

Cone-shaped region of the soma where the axon originates and action potentials are initiated.

Axon Terminal (Terminal Bouton)

Distal secretory region of an axon that releases neurotransmitters.

Myelin Sheath

Protein-lipid covering that insulates axons and increases impulse conduction speed.

Node of Ranvier (Myelin Sheath Gap)

Gap between adjacent myelin segments where axon collaterals may emerge.

Anterograde Transport

Axonal transport of materials from soma toward axon terminals (e.g., mitochondria, enzymes).

Retrograde Transport

Axonal transport from axon terminals toward soma; route for debris or some viruses/toxins.

White Matter

Regions of the CNS composed primarily of myelinated fibers.

Gray Matter

CNS regions containing neuron cell bodies and unmyelinated fibers.

Multipolar Neuron

Structural class with many dendrites and one axon; most common neuron type in CNS.

Bipolar Neuron

Neuron with one dendrite and one axon; found in special sense organs (eye, olfactory mucosa).

Unipolar (Pseudounipolar) Neuron

Sensory neuron with a single process that splits into peripheral and central branches.

Sensory (Afferent) Neuron

Neuron that transmits impulses from receptors toward the CNS; usually unipolar.

Motor (Efferent) Neuron

Neuron that carries impulses from the CNS to effectors; typically multipolar.

Interneuron (Association Neuron)

Neuron located entirely within the CNS that connects sensory and motor pathways; comprises 99% of neurons.