Nervous System and Action Potential Vocabulary

A comprehensive vocabulary flashcard set covering the human nervous system, neuroanatomy, action potential dynamics, synaptic transmission, and meningeal layers based on lecture notes.

Central Nervous System (CNS)

The primary processing center of the body composed of the brain and spinal cord.

Peripheral Nervous System (PNS)

The division of the nervous system consisting of cranial nerves (12 pairs) and spinal nerves (31 pairs) that connect the CNS to the rest of the body.

Somatic Nervous System

The voluntary division of the peripheral nervous system responsible for controlling movement and relaying sensory input to the brain.

Autonomic Nervous System

The involuntary division of the peripheral nervous system that controls internal organ functions, divided into sympathetic and parasympathetic systems.

Sympathetic Nervous System

The branch of the autonomic nervous system responsible for fight or flight responses, mobilizing energy reserves under stress.

Parasympathetic Nervous System

The branch of the autonomic nervous system responsible for resting functions and maintaining homeostasis.

Cell Body (Soma)

The portion of a neuron containing the nucleus and neuroplasma that generates neural impulses.

Neurites

Projections extending from the neuronal cell body that carry impulses, categorized as axons or dendrites.

Axon

A neurite that conducts nerve impulses away from the neuronal cell body.

Dendrites

Neurites that receive incoming signals and conduct impulses toward the neuronal cell body.

Neuron Structure

The functional unit of the nervous system consisting of a cell body, dendrites, axon, myelin sheath, Nodes of Ranvier, and axon terminals.

Nerve Plexus

A network of intersecting nerve fibers formed from the anterior rami of spinal nerves.

Cervical Plexus

A nerve plexus formed by spinal nerves $C1-C4$ that supplies the neck, back, and chest.

Brachial Plexus

A nerve plexus formed by spinal nerves $C5-T1$ that supplies the upper limb, giving rise to nerves such as the ulnar nerve.

Cerebral Cortex

The thin outer layer of neural tissue surrounding the brain responsible for higher-level cognitive and motor processes.

Gyrus

A prominent raised ridge or peak on the surface of the cerebral cortex.

Sulcus

A shallow groove or dip on the surface of the cerebral cortex.

Thalamus

A major subcortical structure acting as a post-office sensory relay station to route information to appropriate cortical areas.

Basal Ganglia

A group of subcortical nuclei involved in the initiation and regulation of movement.

Cerebrum Lobes

The four main structural divisions of each cerebral hemisphere: frontal, parietal, temporal, and occipital lobes.

Frontal Lobe

The anterior lobe of the cerebrum involved in movement control, emotions, thinking, memory, and speech.

Parietal Lobe

The cerebral lobe responsible for processing sensory inputs from the body.

Cerebellum

The posterior region of the brain that coordinates motor movement and maintains posture and balance.

Brainstem

The lower structure connecting the brain to the spinal cord, comprising the midbrain, pons, and medulla oblongata; regulates autonomic functions and breathing.

Spinal Cord Anatomy

The main delivery system connecting the brain and PNS, surrounded by 7 cervical, 12 thoracic, and 5 lumbar vertebrae, as well as the sacrum and coccyx.

Anterior Root

The ventral nerve root exiting the spinal cord that carries motor fibers for motor innervation.

Posterior Root

The dorsal nerve root entering the spinal cord that carries sensory fibers for sensory innervation.

Ganglion

A cluster of neuronal cell bodies in the PNS acting as a message relay system, categorized into sensory (spinal) and autonomic ganglia.

Action Potential Sequence

The sequential voltage changes across a neuronal membrane during nerve impulse propagation, progressing from resting potential through threshold, depolarization, repolarization, and hyperpolarization.

Resting Potential

The baseline membrane potential of a polarized neuron (typically $-70\,mV$) maintained by the Sodium-Potassium Pump pumping $Na^+$ out and $K^+$ in.

Threshold Potential

The critical voltage level (approximately $-55\,mV$) required to open voltage-gated sodium channels and initiate an action potential.

Depolarization

The rapid electrical rise from $-55\,mV$ to $+30\,mV$ caused by an influx of $Na^+$ ions into the neuron.

Repolarization

The phase following peak voltage where sodium channels close and potassium channels open, allowing $K^+$ efflux to drop voltage back toward baseline.

Hyperpolarization

The temporary voltage dip below $-70\,mV$ (around $-85\,mV$) caused by slow-closing $K^+$ channels, entering a temporary lockout state.

Refractory Period

A lockout period after an action potential during which no impulse is possible (absolute) or a stronger stimulus is required (relative).

Saltatory Conduction

The fast mode of electrical impulse propagation along a myelinated axon, where depolarization leaps and receives boosts at the Nodes of Ranvier.

Synaptic Transmission

The chemical process where an incoming action potential opens voltage-gated $Ca^{2+}$ channels, causing vesicles to release neurotransmitters into the synaptic cleft to bind to postsynaptic receptors.

Meninges

The three protective membranes (dura mater, arachnoid mater, and pia mater) that cover and provide structural support for the brain and spinal cord.

Dura Mater

The outermost, tough meningeal layer situated between the skull and the arachnoid mater.

Arachnoid Mater

The web-like middle meningeal layer containing trabeculae that suspend the brain in place.

Pia Mater

The thin, delicate innermost meningeal layer that closely contours the brain surface and contains/secretes spinal fluid.