The Nervous System Exam Flashcards

Comprehensive vocabulary flashcards reviewing the structure, function, divisions, neuroglia, cranial nerves, and pathways of the human nervous system based on exam study material.

Central Nervous System (CNS)

The major division of the nervous system consisting of the brain and spinal cord, functioning as the main control center of the body.

Peripheral Nervous System (PNS)

The division of the nervous system consisting of all nervous structures outside the brain and spinal cord, acting as a communication network.

Afferent Pathway

The nerve pathway that carries sensory information from sensory receptors toward the central nervous system.

Efferent Pathway

The nerve pathway that carries motor commands away from the central nervous system toward effectors.

Homeostasis

The process of maintaining a stable internal environment within the body.

Neuron

A specialized nerve cell that receives, processes, and transmits information using electrical and chemical signals.

Dendrites

Branching structures of a neuron that receive incoming signals from other neurons or sensory receptors.

Cell Body (Soma)

The core processing and maintenance region of a neuron that contains the nucleus and cellular organelles.

Axon

A long nerve fiber that conducts electrical impulses away from the cell body toward other cells.

Myelin Sheath

A fatty insulating layer surrounding many axons that prevents signal degradation and increases impulse conduction speed.

Node of Ranvier

A periodic gap in the myelin sheath along an axon that enables rapid saltatory conduction.

Saltatory Conduction

The rapid propagation of a nerve impulse along a myelinated axon where the signal jumps between Nodes of Ranvier.

Axon Terminals

Distal endings of an axon that store and release chemical neurotransmitters into the synaptic cleft.

Neuroglia (Glial Cells)

Non-neuronal cells that support, nourish, insulate, and protect neurons within the nervous system.

Astrocytes

Star-shaped glial cells in the CNS that provide structural support, regulate the chemical environment, assist in tissue repair, and maintain the blood-brain barrier.

Oligodendrocytes

Glial cells responsible for forming and maintaining the myelin sheath around axons within the central nervous system.

Microglia

Specialized immune cells of the central nervous system that clear cellular debris, pathogens, and dead cells via phagocytosis.

Unipolar Neurons

Neurons possessing a single main process that divides into two branches, typical of sensory neurons in the peripheral nervous system.

Bipolar Neurons

Neurons with two distinct processes—one axon and one dendrite—found in special sense organs such as the retina, olfactory system, and inner ear.

Multipolar Neurons

Neurons featuring one axon and multiple dendrites, representing the most abundant structural neuron type in the central nervous system.

Sensory Neurons

Afferent neurons that transmit sensory information from receptors toward the central nervous system.

Interneurons

Association neurons residing entirely within the CNS that integrate incoming sensory data and connect sensory pathways to motor pathways.

Motor Neurons

Efferent neurons that transmit motor commands from the central nervous system to effectors.

Synapse

The specialized junction where a neuron communicates with another neuron, muscle cell, or gland.

Synaptic Cleft

The microscopic fluid-filled space separating the presynaptic neuron terminal from the postsynaptic cell membrane.

Neurotransmitter

A chemical messenger released by presynaptic axon terminals that diffuses across the synaptic cleft to bind to postsynaptic receptors.

Brain

The primary control organ located in the cranial cavity responsible for processing sensory input, higher mental functions, decision making, and motor control.

Cerebrum

The largest brain division, divided into two hemispheres, responsible for conscious thought, memory, reasoning, voluntary movement, and sensory perception.

Cerebellum

The brain region located posteriorly that coordinates motor activities, balance, posture, and motor learning.

Brain Stem

The brain region connecting the cerebrum to the spinal cord that governs vital autonomic functions such as heart rate, respiration, blood pressure, and swallowing.

Gray Matter

The inner H-shaped core of the spinal cord cross-section containing neuronal cell bodies, dendrites, and unmyelinated synapses for information processing.

White Matter

The outer region of the spinal cord composed primarily of myelinated axon tracts that transport nerve impulses up and down the spinal cord.

Dorsal Root

The posterior nerve root of a spinal nerve that carries incoming sensory signals into the spinal cord.

Ventral Root

The anterior nerve root of a spinal nerve that transmits motor commands away from the spinal cord to effectors.

Conus Medullaris

The tapered, conical lower extremity of the spinal cord located at approximately the L1 to L2 vertebral level in adults.

Cauda Equina

A collection of spinal nerve roots extending inferiorly beyond the conus medullaris resembling a horse's tail.

Reflex

An involuntary, fast, and predictable motor response to a specific stimulus, mediated through spinal cord circuits.

Somatic Nervous System

The voluntary motor division of the PNS controlling skeletal muscle movements and carrying sensory information to the CNS.

Autonomic Nervous System (ANS)

The involuntary division of the PNS that regulates smooth muscle, cardiac muscle, and gland secretions to maintain internal homeostasis.

Sympathetic Nervous System

The thoracolumbar division of the ANS that mediates the 'fight-or-flight' response, increasing heart rate, dilating bronchioles and pupils, and inhibiting digestion.

Parasympathetic Nervous System

The craniosacral division of the ANS that mediates the 'rest-and-digest' functions, promoting energy conservation, slowing heart rate, and stimulating digestion.

Olfactory Nerve (CN I)

Cranial nerve I, responsible exclusively for transmitting sensory information for the sense of smell.

Optic Nerve (CN II)

Cranial nerve II, responsible exclusively for transmitting visual sensory input from the retina to the brain.

Oculomotor Nerve (CN III)

Cranial nerve III, controlling most ocular muscles for eye movement and mediating pupil constriction.

Trochlear Nerve (CN IV)

Cranial nerve IV, providing motor innervation to the superior oblique muscle for eye movement.

Trigeminal Nerve (CN V)

Cranial nerve V, providing sensory input for facial touch and pain, as well as motor control for muscles of mastication (chewing).

Abducens Nerve (CN VI)

Cranial nerve VI, controlling lateral eye movement via motor innervation of the lateral rectus muscle.

Facial Nerve (CN VII)

Cranial nerve VII, controlling muscles of facial expression, taste sensation on the anterior two-thirds of the tongue, and lacrimal/salivary secretions.

Vestibulocochlear Nerve (CN VIII)

Cranial nerve VIII, responsible for sensory transmission of hearing and equilibrium (balance).

Glossopharyngeal Nerve (CN IX)

Cranial nerve IX, governing swallowing, posterior tongue taste, pharyngeal sensory input, and parotid salivary gland stimulation.

Vagus Nerve (CN X)

Cranial nerve X, providing major parasympathetic regulation to thoracic and abdominal organs, along with motor control for speech and swallowing.

Accessory Nerve (CN XI)

Cranial nerve XI, supplying motor control to the sternocleidomastoid and trapezius muscles for head turning and shoulder shrugging.

Hypoglossal Nerve (CN XII)

Cranial nerve XII, supplying motor innervation exclusively to muscles controlling tongue movement.

Mechanoreceptors

Sensory receptors that respond to physical mechanical forces such as pressure, touch, vibration, stretch, sound, and balance.

Thermoreceptors

Sensory receptors that detect changes in temperature.

Nociceptors

Specialized sensory receptors that detect harmful or potentially tissue-damaging stimuli and transmit pain signals.

Chemoreceptors

Sensory receptors that respond to chemical concentration changes, including gustation, olfaction, arterial oxygen, carbon dioxide, and blood pH.

Photoreceptors

Specialized sensory receptors located in the retina of the eye that detect light stimuli for visual perception.

Receptor

A specialized sensory structure or cell that detects internal or external environmental stimuli.

Effector

A muscle or gland cell that executes a functional bodily response to motor signals from the central nervous system.

Stimulus to Response Pathway

The functional pathway wherein a stimulus is detected by a receptor, transmitted by sensory neurons to the CNS, processed, sent through motor neurons, and executed by an effector.