Central Nervous System – Key Vocabulary

A comprehensive set of vocabulary flashcards covering structural elements, functional divisions, protective features, and key physiological concepts of the central nervous system.

Central Nervous System (CNS)

The brain and spinal cord; integrates and processes information.

Peripheral Nervous System (PNS)

All neural tissue outside the CNS; includes cranial and spinal nerves.

Afferent Division

Sensory pathways bringing information from the body to the CNS.

Efferent Division

Motor pathways carrying commands from the CNS to effector organs.

Somatic Nervous System

Efferent fibers that innervate skeletal muscles for voluntary movement.

Autonomic Nervous System (ANS)

Efferent fibers that regulate smooth muscle, cardiac muscle, and glands.

Sympathetic Nervous System

ANS subdivision that mediates "fight-or-flight" responses.

Parasympathetic Nervous System

ANS subdivision that promotes "rest-and-digest" functions.

Enteric Nervous System (ENS)

Intrinsic nerve network of the digestive tract that can function independently.

Neuron

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

Afferent Neuron

Sensory neuron that conveys impulses to the CNS.

Efferent Neuron

Motor neuron that transmits impulses from the CNS to effectors.

Interneuron

Neuron located entirely within the CNS; integrates afferent input and coordinates efferent output.

Glial Cells

Support cells of the CNS; include astrocytes, oligodendrocytes, microglia, and ependymal cells.

Astrocyte

Star-shaped glial cell that supports neurons, forms scar tissue, and helps create the blood–brain barrier.

Oligodendrocyte

Glial cell that forms myelin sheaths around CNS axons.

Microglia

Immune-like glial cells that act as phagocytes within the CNS.

Ependymal Cell

CNS glial cell lining ventricles; produces and circulates cerebrospinal fluid.

Meninges

Three protective membranes—dura mater, arachnoid mater, pia mater—around the brain and spinal cord.

Dura Mater

Tough, outermost meningeal layer.

Arachnoid Mater

Middle, web-like meningeal layer; houses cerebrospinal fluid in its space.

Pia Mater

Delicate, innermost meningeal layer that adheres to brain surface.

Cerebrospinal Fluid (CSF)

Shock-absorbing liquid that cushions and nourishes the CNS.

Blood–Brain Barrier (BBB)

Selective capillary barrier that limits substance exchange between blood and brain tissue.

Plasticity

Ability of the brain to remodel synaptic connections in response to experience or injury.

Broca’s Area

Left frontal cortical region responsible for speech production.

Wernicke’s Area

Cortical region at parietal-temporal-occipital junction responsible for language comprehension.

Primary Motor Cortex

Frontal lobe region that controls voluntary skeletal muscle movements.

Somatosensory Cortex

Parietal lobe region that processes touch, pressure, pain, and temperature.

Homunculus

Body map illustrating cortical representation of sensory or motor functions.

Prefrontal Association Cortex

Frontal area involved in planning, decision-making, and personality.

Default Mode Network

Set of cortical regions more active during rest and mind-wandering than during focused tasks.

Basal Nuclei (Basal Ganglia)

Deep gray matter masses that inhibit muscle tone and refine purposeful movements.

Thalamus

Major sensory relay station that preliminarily processes all ascending input to the cortex.

Hypothalamus

Homeostatic control center linking nervous and endocrine systems; regulates temperature, hunger, etc.

Limbic System

Functional ring of structures mediating emotion, behavior, motivation, and memory.

Hippocampus

Limbic structure critical for forming declarative long-term memories.

Amygdala

Limbic nucleus involved in fear, aggression, and emotional memory.

Cerebellum

Highly folded structure under occipital lobe; coordinates balance and skilled movements.

Vestibulocerebellum

Cerebellar region regulating balance and eye movements.

Spinocerebellum

Cerebellar region enhancing muscle tone and coordinating skilled movement.

Cerebrocerebellum

Cerebellar region involved in planning and initiating voluntary activity.

Brain Stem

Midbrain, pons, and medulla; controls vital functions and houses cranial nerve nuclei.

Reticular Activating System (RAS)

Brain-stem network that influences overall cortical alertness.

Electroencephalogram (EEG)

Recording of cortical postsynaptic activity showing alpha, beta, theta, delta, and gamma waves.

Slow-Wave Sleep

Deep, restorative sleep stage characterized by delta EEG waves.

Paradoxical (REM) Sleep

Dreaming sleep stage with rapid eye movements and EEG patterns similar to wakefulness.

Short-Term Memory

Transient storage lasting seconds to hours; relies on temporary synaptic changes.

Long-Term Memory

Stable storage lasting days to years; involves structural synaptic changes and new protein synthesis.

Working Memory

Temporary holding and manipulation of information needed for cognitive tasks.

Retrograde Amnesia

Loss of previously formed memories, often from brain injury.

Anterograde Amnesia

Inability to form new long-term memories after brain damage.

Norepinephrine

Brain neurotransmitter involved in arousal, mood, and the limbic "reward" pathways.

Dopamine

Neurotransmitter essential for motivation, movement control, and reward signaling.

Serotonin

Neurotransmitter influencing mood, appetite, and sleep.

Selective Serotonin Reuptake Inhibitor (SSRI)

Antidepressant class that prolongs serotonin action by blocking reuptake.

Serotonin–Norepinephrine Reuptake Inhibitor (SNRI)

Drug that blocks reuptake of both serotonin and norepinephrine.

Tricyclic Antidepressant (TCA)

Older antidepressant that blocks reuptake of serotonin, norepinephrine, and sometimes dopamine.

Monoamine Oxidase Inhibitor (MAOI)

Antidepressant that prevents enzymatic breakdown of monoamine neurotransmitters.

Spinal Cord

Long CNS cylinder that relays information and mediates spinal reflexes.

Ascending Tract

Bundle of spinal white-matter fibers carrying sensory information to the brain.

Descending Tract

Bundle of spinal fibers conveying motor commands from the brain.

Dorsal Root

Spinal nerve branch containing afferent sensory fibers and a dorsal root ganglion.

Ventral Root

Spinal nerve branch containing efferent motor fibers.

Dorsal Horn

Gray-matter region housing interneurons that receive sensory input.

Ventral Horn

Gray-matter region containing somatic motor neuron cell bodies.

Lateral Horn

Spinal gray-matter region with autonomic efferent neuron cell bodies.

Reflex Arc

Neural pathway mediating an involuntary response; includes receptor, afferent neuron, integration center, efferent neuron, and effector.

Monosynaptic Reflex

Reflex arc with a single synapse between afferent and efferent neurons (e.g., knee-jerk).

Polysynaptic Reflex

Reflex involving one or more interneurons and multiple synapses.