Practice Flashcards: Nervous System Organization

A collection of vocabulary flashcards covering the structural organization, cellular components, and functional divisions of the human nervous system based on the provided neuroanatomy lecture notes.

Ischemia

Deficient blood flow to the brain due to functional constriction of a blood vessel by a clot.

Hemorrhagic stroke

A type of stroke resulting from a burst vessel bleeding into the brain.

Tissue plasminogen activator (t-PA)

A drug that breaks up clots to restore normal blood flow; it must be administered within $3$ hours of an ischemic stroke to be effective.

Nuclei

Clusters of neurons that have specific functions in mediating behavior; derived from the Latin word "nux" meaning "nut."

Tracts

Large collections of axons projecting toward or away from a nucleus or layer in the CNS or distinctive fiber pathways.

Neuroplasticity

The capacity of the brain to undergo changes, such as neurons changing their connections or the brain gaining and losing neurons and glia.

Phenotypic plasticity

The capacity to express widely differing phenotypes due to epigenetic influences and experiences during a life span.

Rostral

An anatomical location oriented toward the "beak" (rostrum) or front of the brain.

Caudal

An anatomical location oriented toward the "tail" (caudum) or back of the brain.

Dorsal

An anatomical location oriented toward the "back" (dorsum) or top of the brain.

Ventral

An anatomical location oriented toward the "stomach" (ventrum) or bottom of the brain.

Anterior

A term describing brain structures located in the front, also referred to as frontal.

Posterior

A term describing brain structures located behind other structures.

Lateral

A term describing structures located at the side of the brain.

Medial

A term describing structures located at the center or in between other structures.

Coronal section

A brain section cut in a vertical plane from the crown of the head down, providing a frontal view.

Horizontal section

A brain section cut along the horizon, providing a dorsal view from above.

Sagittal section

A brain section cut lengthways from front to back, providing a medial view from the side.

Ipsilateral

A term for structures that lie on the same side of the body.

Contralateral

A term for structures that lie on opposite sides of the body relative to each other.

Bilateral

A term referring to corresponding structures that lie in each of the brain's two hemispheres.

Proximal

A term for structures that are located close to one another.

Distal

A term for structures that are located far from one another.

Afferent

A term for any movement or pathway directed toward a brain structure, typically associated with sensory information.

Efferent

A term for any movement or pathway directed away from a brain structure, typically associated with motor output.

Central nervous system (CNS)

The division of the nervous system consisting of the brain and spinal cord, both encased in bone.

Peripheral nervous system (PNS)

The division of the nervous system consisting of all structures outside the CNS, including the somatic and autonomic nervous systems.

Somatic nervous system (SNS)

A division of the PNS that transmits sensory information to the CNS and produces movements via spinal and cranial nerves.

Autonomic nervous system (ANS)

A division of the PNS that controls internal organs through sympathetic (arousing) and parasympathetic (calming) nerves.

Meninges

A triple-layered set of membranes (dura mater, arachnoid membrane, and pia mater) that encases the brain and spinal cord.

Cerebrospinal fluid (CSF)

A fluid that cushions the brain and spinal cord from shock; it circulates through the ventricles and subarachnoid space.

Blood-brain barrier

A protective barrier formed by tight junctions between capillary cells, stimulated by astroglia, that limits chemical movement into the CNS.

Neural stem cell

A self-renewing, multipotential germinal cell that gives rise to all types of neurons and glia in the nervous system.

Blasts

Nondividing primitive nervous system cell types; neuroblasts differentiate into neurons, and glioblasts differentiate into glia.

Bipolar neuron

A simple sensory receptor consisting of a cell body with a dendrite on one side and an axon on the other, found in the retina.

Somatosensory neuron

A sensory neuron that projects from body receptors into the spinal cord with connected dendrites and axons for speed.

Interneurons

Neurons within the brain and spinal cord that link sensory and motor activity; examples include stellate, pyramidal, and Purkinje cells.

Motor neurons

Neurons located in the brainstem and spinal cord that project to muscles; they are known as the "final common path."

Astroglia

Star-shaped glial cells that provide structural support and nutrition to neurons and help form the blood-brain barrier.

Microglia

Small glial cells that serve a defensive function by fighting infection and removing debris.

Oligodendroglia

Asymmetrical glial cells that form insulating myelin around axons within the brain and spinal cord (CNS).

Schwann cells

Asymmetrical glial cells that wrap around peripheral nerves in the PNS to form insulating myelin.

Gray matter

Brain tissue predominantly composed of neuronal cell bodies and capillaries, giving it a gray-brown appearance.

White matter

Brain tissue composed largely of myelinated nerve fibers (axons) that connect gray matter regions.

Prosencephalon

The "front brain" in the primitive three-part brain model, responsible for olfaction.

Mesencephalon

The "middle brain" in the primitive three-part brain model, serving as the seat of vision and hearing.

Rhombencephalon

The "hindbrain" in the primitive three-part brain model, responsible for controlling movement and balance.

Diencephalon

The "between brain" structure that includes the thalamus, hypothalamus, and epithalamus.

Telencephalon

The "endbrain" structure which includes the cerebral hemispheres (neocortex, basal ganglia, and limbic system).

Dermatome

A body region or "skin cut" that corresponds to a recurring unit of the spinal cord and its spinal nerve fibers.

Bell-Magendie law

The principle stating that the dorsal (posterior) roots of the spinal cord are sensory and the ventral (anterior) roots are motor.

Reflexes

Specific movements produced by spinal cord neural circuits that are elicited by specific forms of sensory stimulation.

Vagus nerve

The $10^{th}$ cranial nerve, which innervates most internal organs including the heart, blood vessels, and viscera.

Cerebellum

A major hindbrain structure with a folded surface (folia) that coordinates motor functions, motor learning, and equilibrium.

Reticular formation

A network of nuclei in the hindbrain core that controls sleeping, waking, and general arousal/consciousness.

Tectum

The "roof" of the midbrain; includes the superior colliculi (visual) and inferior colliculi (auditory) for orienting behaviors.

Tegmentum

The "floor" of the midbrain; contains motor-related nuclei such as the red nucleus, substantia nigra, and periacqueductal gray matter.

Hypothalamus

A diencephalon structure containing $22$ nuclei that regulate motivated behaviors such as feeding, sleeping, and sexual activity.

Thalamus

The largest diencephalon structure, composed of $20$ nuclei, which acts as a relay hub for sensory information heading to the cortex.

Basal ganglia

A collection of forebrain nuclei (caudate, putamen, and globus pallidus) involved in motor regulation and associative learning.

Limbic system

A functional circuit (including the amygdala, hippocampus, and cingulate cortex) involved in emotion, memory, and spatial navigation.

Hippocampus

A limbic structure in the temporal lobe that participates in personal memory and spatial navigation.

Neocortex

The "new bark" or outer layer of the forebrain, consisting of six layers of gray matter, responsible for higher functions.

Gyrus

A ridge on the heavily wrinkled surface of the neocortex.

Sulcus

A shallow cleft or groove on the surface of the neocortex.

Fissure

A deep cleft in the neocortex that extends far enough to indent the brain's ventricles.

Primary areas

Cortical regions that receive direct projections from sensory systems or send motor projections to the muscles.

Secondary areas

Cortical regions adjacent to primary areas that elaborate sensory information or organize motor commands.

Tertiary areas

Also called association areas, these cortical regions mediate complex activities such as language, planning, and memory.

Brodmann’s map

A cytoarchitectonic map that parcels the neocortex into subregions (originally $52$) based on cellular arrangement.

Connectome

A three-dimensional visualization of all the axon pathways and connections within the human brain.

Decussations

The crossings of sensory and motor fibers along the midline of the nervous system, resulting in contralateral control.