Coordination and Control: The Nervous System

Vocabulary flashcards covering the structural and functional divisions of the nervous system, neuron anatomy, nerve impulse physiology, spinal cord structures, and various neurological disorders.

Central Nervous System (CNS)

Structural division consisting of the brain and the spinal cord.

Peripheral Nervous System (PNS)

All nerves located outside of the CNS, including the Cranial Nerves.

Somatic Nervous System

A functional division controlled voluntarily; its effectors are skeletal muscles.

Autonomic Nervous System (ANS)

An involuntary functional division, also called the Visceral Nervous System, whose effectors are smooth muscle, cardiac muscle, and glands.

Cell body

The part of a neuron that contains the nucleus and organelles.

Dendrites

Neuron fibers that function as receptors and conduct impulses toward the cell body.

Axons

Neuron fibers that conduct impulses away from the cell body.

Myelin

Fatty material covering some axons for insulation, protection, and to help speed impulses.

Schwann cells

Specialized cells in the PNS that wrap around the axon and produce myelin.

Nodes

Spaces or gaps between individual Schwann cells along an axon.

Neurilemma

The outermost layer of a Schwann cell that helps some peripheral nerves in repair.

White Matter

Nervous tissue composed of myelinated fibers.

Grey Matter

Nervous tissue composed of unmyelinated fibers.

Sensory (afferent) neurons

Neurons that carry impulses toward the brain or CNS.

Motor (efferent) neurons

Neurons that carry impulses away from the brain to the body.

Mixed Nerves

Nerves containing a combination of both sensory and motor fibers.

Interneuron

Neurons that relay information specifically within the CNS.

Nerve

A fiber bundle located within the Peripheral Nervous System (PNS).

Tract

A fiber bundle located in the Central Nervous System (CNS), found in both the brain and spinal cord.

Endoneurium

The membrane that covers an individual nerve fiber.

Perineurium

The membrane that covers nerve fascicles.

Epineurium

The membrane that covers the whole nerve.

Neuroglia

Also known as Glial Cells or "Nerve Glue," these non-conducting cells protect, nourish, and support neurons.

Astrocytes

A type of neuroglia attached to capillaries in the brain involved in fluid regulation and repair.

Action Potential

A sudden electrical change at the membrane caused by a local reversal in membrane potential.

Depolarization

The stage of an action potential where $Na^+$ flows into the cell, raising the internal charge.

Repolarization

The stage where $K^+$ leaves the cell and the $Na^+$ and $K^+$ return to a resting state via active transport.

Sodium-potassium Pump

An active transport mechanism that uses ATP to move ions against their gradient to restore the resting state.

Saltatory conduction

The process in which an impulse sparks or jumps across nodes in myelinated fibers, speeding up conduction.

Synapse

The point of junction for transmitting a nerve impulse between cells.

Reuptake

The process where neurotransmitters are taken back into the pre-synaptic cell after diffusion.

Gray Commissure

The structure that connects the right and left sides of the H-shaped internal gray matter in the spinal cord.

Dorsal root ganglion

A swelling of grey matter that contains the cell bodies of sensory neurons.

Plexuses

Large anterior networks of nerves, such as the Cervical, Brachial, and Lumbosacral networks.

Dermatomes

Distinct regions of the body surface supplied by a specific spinal nerve, used to map spinal injury levels.

Reflex Arc

The complete pathway through the nervous system from a stimulus to a response.

Effector

A muscle or gland outside the CNS that carries out a nervous system command.

Sympathetic Nervous System

The thoracolumbar division ($T_1$ to $L_2$) of the ANS that triggest the "Fight or Flight" response.

Parasympathetic Nervous System

The craniosacral division of the ANS that handles "Rest and Digest" functions and maintains homeostasis.

Adrenergic

Refers to the sympathetic neurotransmitters related to adrenaline/epinephrine.

Cholinergic

Refers to the parasympathetic neurotransmitter acetylcholine ($ACh$).

Lumbar puncture

A procedure to remove cerebrospinal fluid ($CSF$) from the space between the $3rd$ and $4th$ lumbar vertebra.

Multiple Sclerosis (MS)

An autoimmune disease characterized by a damaged myelin sheath and degenerating nerve fibers.

Amyotrophic Lateral Sclerosis (ALS)

A disorder where motor neurons are destroyed, causing progressive muscle atrophy and weakness.

Hemiplegia

Paralysis affecting only one side of the body.

Paraplegia

Paralysis affecting both lower limbs.

Quadriplegia

Also known as tetraplegia, this is the paralysis of all $4$ extremities.

Neuropathy

A general term used for any disease or disorder of the nerves.

Herpes Zoster

Commonly known as shingles, this condition follows a dermatome and causes painful, draining lesions.

Guillain-Barre Syndrome

A polyneuropathy characterized by progressive weakness and paralysis that often follows a viral infection.