BIOL 213 Nervous System Test

Comprehensive vocabulary flashcards covering the structural divisions, neuroglial cells, neuronal anatomy, electrophysiology, neurotransmitters, neural circuits, and fiber classifications of the nervous system.

Sensory Input

The nervous system function of monitoring internal and external stimuli occurring inside and outside the body.

Integration

The processing and interpretation of sensory input by the nervous system to determine the appropriate response.

Motor Output

The nervous system response that activates effector organs, such as muscles and glands, in reaction to stimuli.

Central Nervous System (CNS)

The division of the nervous system consisting of the brain and spinal cord that acts as the integrative and control center.

Peripheral Nervous System (PNS)

The division of the nervous system composed of paired cranial and spinal nerves that serves as communication lines between the CNS and the rest of the body.

Sensory (Afferent) Division

The subdivision of the PNS consisting of somatic and visceral sensory nerve fibers that conducts impulses from sensory receptors toward the CNS.

Motor (Efferent) Division

The subdivision of the PNS consisting of motor nerve fibers that conducts impulses from the CNS to effector organs, including muscles and glands.

Somatic Nervous System

The voluntary motor component of the peripheral nervous system that conducts impulses from the CNS to control skeletal muscles.

Autonomic Nervous System (ANS)

The involuntary visceral motor division of the PNS that regulates and conducts impulses from the CNS to cardiac muscle, smooth muscle, and glands.

Sympathetic Division

The subdivision of the autonomic nervous system responsible for 'Fight, Fright and Flight,' mobilizing body systems during emergency situations.

Parasympathetic Division

The subdivision of the autonomic nervous system that conserves energy and promotes nonemergency 'Resting and Digesting' maintenance functions.

Neuroglia (Glial Cells)

Non-excitable supporting cells that provide scaffolding, insulation, guidance, and metabolic support for neurons.

Astrocytes

The largest and most abundant glial cells in the CNS, responsible for maintaining the blood-brain barrier, providing nutrients to neurons, and forming scar tissue after damage.

Microglia

Specialized phagocytic neuroglia in the CNS that act as immune defenses ('the brain's garbage truck') by removing pathogens, cell debris, and metabolic waste.

Ependymal Cells

Atypical simple cuboidal or columnar epithelial glial cells possessing cilia that line the brain ventricles and the central canal of the spinal cord to produce, monitor, and circulate cerebrospinal fluid (CSF).

Oligodendrocytes

Branching neuroglial cells of the CNS that produce myelin sheaths around CNS axons and provide structural support.

Satellite Cells

PNS neuroglial cells analogous to CNS astrocytes that surround and metabolically support neuron cell bodies within ganglia.

Schwann Cells

PNS neuroglial cells that repeatedly wrap their plasma membrane $20$ to $40$ layers thick around peripheral axons to form the insulating myelin sheath and neurilemma.

Neurilemma

The outer nucleated cytoplasmic layer of a Schwann cell that remains on the exterior of the myelin sheath in the peripheral nervous system (absent in the CNS).

Nodes of Ranvier

Gaps between adjacent myelin-forming cells along an axon where axon collaterals can emerge and nerve impulse conduction velocity is increased.

Dendrites

Short, tapering, and diffusely branched extensions from the neuronal soma that function as the receptive or sensory input regions.

Axon

The single, long neuronal extension that generates and conducts action potentials away from the soma toward axonal terminals to secrete neurotransmitters.

Axon Hillock

The cone-shaped transition zone of the neuron cell body from which the axon originates and action potentials are generated.

Nissl Bodies

Well-developed rough endoplasmic reticulum located within the neuron cell body (soma) active in protein synthesis.

Anterograde Transport

Cellular movement of materials along an axon traveling away from the cell body toward the axonal terminal.

Retrograde Transport

Cellular movement of materials along an axon traveling away from the axonal terminal back toward the soma.

White Matter

Regions of the brain and spinal cord consisting of dense collections of myelinated nerve fibers.

Gray Matter

Regions of the central nervous system composed primarily of neuronal cell bodies (soma), dendrites, and unmyelinated fibers.

Multiple Sclerosis (MS)

An autoimmune disease primarily affecting young adults where antibodies destroy CNS myelin sheaths, converting them into nonfunctional hardened scleroses and disrupting nerve impulse conduction.

Neuromyelitis Optica (Devic's Disease)

An important differential diagnosis for multiple sclerosis characterized particularly by bilateral optic neuritis.

Oligoclonal Bands

Abnormal immunoglobulin protein bands detected in cerebrospinal fluid analysis used to assist in the diagnosis of multiple sclerosis.

Copazone

An immune system-modifying medication used in the management of multiple sclerosis to hold symptoms at bay and reduce complications and disability.

Multipolar Neurons

The structural class of neurons having three or more processes (one axon and multiple dendrites); they are the most abundant neurons in the body and CNS.

Bipolar Neurons

A rare structural neuron class possessing exactly two processes (one axon and one dendrite), typically found in special sensory organs such as the olfactory mucosa and retina.

Unipolar Neurons (Pseudounipolar Neurons)

A structural class of neurons with a single short process emerging from the soma that branches into central and peripheral axons, found mainly in dorsal root and cranial sensory ganglia.

Interneurons (Association Neurons)

Functional class of neurons located entirely within the CNS between sensory and motor neurons that process information and coordinate neural pathways.

Electrical Synapse

A rapid, less common synapse featuring gap junctions that allow direct ionic current between cells, involved in sleep arousal, mental attention, and water/ion homeostasis.

Chemical Synapse

A junction specialized for the unidirectional transfer of information via neurotransmitter release from presynaptic vesicles across a fluid gap to postsynaptic membrane receptors.

Synaptic Cleft

The fluid-filled space separating the presynaptic axonal terminal from the postsynaptic neuron membrane, ensuring unidirectional chemical communication.

Axosomatic Synapse

A structural type of synapse formed between the axonal terminal of a presynaptic neuron and the cell body (soma) of a postsynaptic neuron.

Axodendritic Synapse

A synaptic connection formed between the axon terminal of one presynaptic neuron and a dendrite of a postsynaptic neuron.

Axoaxonic Synapse

A synaptic connection formed directly between the axon of one neuron and the axon of another neuron.

Dopamine

A feel-good amino acid neurotransmitter whose release is stimulated by L-Dopa and amphetamines and blocked by cocaine; a deficiency is implicated in Parkinson's disease.

Norepinephrine (NE)

A feel-good neurotransmitter whose release is enhanced by amphetamines and reuptake inhibited by tricyclic antidepressants and cocaine; deficiency results in depression.

Serotonin

An amino acid-derived neurotransmitter that regulates sleep, mood, appetite, nausea, and migraines; reuptake is blocked by Prozac and LSD, and deficiency can lead to anxiety and depression.

Endorphins

Natural opiate peptide neurotransmitters released during strenuous exercise ('runner's high' or second wind) that inhibit pain transmission and promote well-being.

Enkephalins

Peptide neurotransmitters that inhibit pain reception, increase substantially during pregnancy, and are suppressed by opioids such as morphine and heroin.

Excitatory Neurotransmitters

Neurochemicals (such as glutamate) that induce depolarization of the postsynaptic membrane, bringing it closer to firing threshold.

Inhibitory Neurotransmitters

Neurochemicals (such as GABA and glycine) that induce hyperpolarization of the postsynaptic membrane, driving it away from firing threshold.

Voltage

The measure of potential energy generated by separated electrical charge, expressed as potential difference.

Current (I)

The flow of electrical charge in the form of ions moving between two points across a biological barrier.

Resistance ($R$)

The hindrance to the flow of electrical charge, primarily provided in neural tissue by the plasma membrane.

Chemically Gated (Ligand-Gated) Channels

Membrane ion channels that open or close in direct response to the binding of a specific chemical neurotransmitter.

Voltage-Gated Channels

Membrane ion channels that open and close in response to changes in the transmembrane electrical potential.

Mechanically Gated Channels

Membrane ion channels that open or close in response to physical deformation, pressure, or stretch applied to the receptor.

Resting Membrane Potential

The electrical potential difference across a resting neuronal membrane of approximately $-70\text{ mV}$, characterized by a negative intracellular charge relative to the extracellular fluid.

Sodium-Potassium Pump

An ATP-dependent active transport protein complex that maintains resting ionic concentration gradients by pumping $3\,Na^+$ out of the cell for every $2\,K^+$ pumped in.

Depolarization

A reduction in membrane potential toward zero where the intracellular surface becomes less negative than the resting value, increasing the likelihood of nerve impulse production.

Action Potential (AP)

A brief reversal of membrane potential with a total amplitude of approximately $100\text{ mV}$ that propagates along an axon without decreasing in magnitude.

Repolarization

The phase of an action potential in which slow inactivation gates close $Na^+$ channels and voltage-sensitive $K^+$ channels open, allowing $K^+$ efflux to restore internal resting negativity.

Hyperpolarization

An increase in membrane potential away from zero where the intracellular environment becomes more negative than the resting potential due to prolonged $K^+$ efflux, decreasing impulse probability.

Divergence

A neuronal circuit configuration where a single incoming neuron branches to distribute signals to multiple postsynaptic neurons or pathways.

Convergence

A neuronal circuit configuration where multiple presynaptic inputs synapse onto a single postsynaptic neuron or pool to control one shared output.

Parallel Processing

An integration circuit pattern dependent on divergence that enables simultaneous analysis of the same sensory event by multiple separate neural pathways.

Reverberating Circuit

A positive feedback neural pathway where collateral axon branches loop back to restimulate upstream neurons, maintaining continuous activity until synaptic fatigue or inhibition occurs.

Group A Fibers

Large-diameter, heavily myelinated somatic sensory and motor nerve fibers possessing the fastest electrical conduction velocities.

Group B Fibers

Intermediate-diameter, lightly myelinated autonomic nerve fibers characterized by moderate conduction speeds.

Group C Fibers

Smallest-diameter, unmyelinated autonomic and sensory nerve fibers that transmit slow pain and other signals at the lowest conduction velocities.

Psalm 1

A wisdom psalm outlining two opposing life paths, contrasting the ungodly route with the narrow, disciplined, and uphill path of the righteous who delight in and meditate on God's law day and night.

Psalm 51

A psalm of David expressing deep repentance and heartfelt confession of personal sin, crying out for God's mercy, spiritual cleansing, and the creation of a clean heart.

Hebrews 12:1-2

A New Testament passage comparing the life of faith to running an endurance race with perseverance, urging believers to strip away every hindrance and sin while fixing their eyes on Jesus.

1 John 1:9

A passage assuring believers that if they confess their sins, God is faithful and just to forgive and cleanse them from all unrighteousness, functioning like an ongoing spiritual shower.

Mark 1:35

A Gospel account describing Jesus rising very early in the morning while it was still dark to depart to a solitary place to pray, modeling quiet and prioritized communion with God.

John 1:1

The opening passage stating that 'in the beginning was the Word, and the Word was with God, and the Word was God,' highlighting divine truth as essential spiritual nutrition.

John 1:14

The foundational Incarnation passage declaring that 'the Word became flesh and dwelt among us,' revealing the fullness of divine glory, grace, and truth in bodily human form.

Cerebral Cortex

The superficial mantle of gray matter comprising roughly $40\%$ of total brain mass that enables conscious awareness, sensory perception, voluntary motor initiation, communication, and memory.

Gyri

Elevated ridges or convolutions of cortical tissue visible across the surface of the cerebral hemispheres.

Sulci

Shallow indentations or grooves that separate adjacent convolutions on the cerebral surface.

Longitudinal Fissure

The deep anatomical cleft that divides the cerebrum into right and left cerebral hemispheres.

Central Sulcus

The frontal plane groove separating the frontal lobe from the parietal lobe and dividing the precentral gyrus from the postcentral gyrus.

Primary Motor Cortex

A motor region located in the precentral gyrus consisting of pyramidal neurons whose axons form the corticospinal tracts to direct conscious, voluntary skeletal muscle movements.

Motor Homunculus

A distorted graphical representation along the precentral gyrus mapping the relative proportions of cortical motor tissue allocated to specific bodily muscles.

Premotor Cortex

A cortical motor planning area positioned immediately anterior to the precentral gyrus that coordinates learned, sequential, or patterned motor actions.

Broca's Area

A specialized motor speech center located anterior to the inferior premotor region in the dominant hemisphere that directs the muscular contractions necessary for articulate vocal expression.

Frontal Eye Field

A cortical area located anterior to the premotor cortex and superior to the motor speech area that directs voluntary scanning movements of the eyes.

Primary Somatosensory Cortex

A sensory area located in the postcentral gyrus that receives and localizes tactile, thermal, pain, and proprioceptive inputs from the skin and musculoskeletal system.

Somatosensory Association Cortex

An integration area located immediately posterior to the postcentral gyrus that synthesizes sensory inputs to determine the size, texture, and physical orientation of touched objects.

Primary Visual Cortex

The sensory receptive area located on the extreme posterior tip of the occipital lobe and buried along the calcarine sulcus that receives retinotopic visual signals.

Visual Association Area

An occipital cortical area surrounding the calcarine fissure that interprets visual inputs by evaluating color, shape, form, and movement.

Primary Auditory Cortex

A sensory area positioned on the superior margin of the temporal lobe that receives auditory nerve impulses and decodes pitch, rhythm, and volume.

Auditory Association Area

A temporal cortical region located posterior to the primary auditory receiver that references past acoustic memories to interpret sound significance.

Wernicke's Area

A language association region situated near the lateral sulcus that decodes unfamiliar words and formulates semantic instructions transmitted to speech motor centers.

Prefrontal Cortex

The anterior portion of the frontal lobe governing intellect, cognition, personality, abstract reasoning, future planning, and conscience.

Commissural Fibers

Myelinated white matter tracts, including the corpus callosum, that connect corresponding gray areas between the left and right cerebral hemispheres.

Association Fibers

Intrahemispheric white matter tracts that link distinct cortical areas situated within the same cerebral hemisphere.

Projection Fibers

Vertical white matter tracts forming the internal capsule and corona radiata that tie the cerebral cortex to lower brain stem regions and the spinal cord.

Basal Nuclei

Subcortical gray matter masses—including the caudate, putamen, and globus pallidus—that coordinate the onset, cessation, and intensity of skeletal movements while suppressing extraneous muscle activity.

Cerebellum

A dorsal hindbrain structure that subconsciously coordinates the timing, balance, and pattern of skeletal muscle contractions using sensory blueprints.

Arbor Vitae

The treelike branching pattern of white matter tracts visible on sagittal sections of the cerebellar hemispheres.

Cerebellar Peduncles

Three paired fiber bundles (superior, middle, and inferior) conveying ipsilateral neural communication between the hindbrain coordinator and the midbrain, pons, and medulla.