Introduction to the Nervous System

Vocabulary practice flashcards covering structural and functional divisions, neuron anatomy, glial cells, synapses, neurotransmitters, and nerve connective tissue coverings based on Chapter 14 lecture notes.

Amyotrophic Lateral Sclerosis (ALS)

A neurodegenerative disease impacting motor neurons that govern voluntary movement via skeletal muscle, progressively causing patients to lose the ability to move, eat, talk, and breathe.

Sensory Function

The nervous system function where sensory receptors detect internal changes (such as blood pressure) or external changes (such as outside temperature).

Integrative Function

The nervous system function that analyzes incoming sensory stimuli and makes decisions for appropriate bodily responses.

Motor Function

The nervous system function in which effectors (such as muscles or glands) create a response directed by the nervous system.

Central Nervous System (CNS)

The structural division of the nervous system consisting of the brain and spinal cord, acting as the primary control center of the body.

Peripheral Nervous System (PNS)

The structural division comprising all nervous tissue outside the CNS, including cranial nerves, spinal nerves, and ganglia, serving as the communication link between the body and the CNS.

Ganglia

Clusters or groups of neuron cell bodies located outside of the central nervous system.

Nerve

A bundle of neuron axons located within the peripheral nervous system.

Afferent

Carrying incoming sensory information arriving at the CNS from the PNS.

Efferent

Carrying outgoing motor (action) information exiting the CNS to the PNS.

Somatic Sensory

The functional sensory branch collecting conscious input from the outer body, skin, joints, skeletal muscles, and special sense organs (touch, pain, pressure, vibration, taste, sight, and proprioception).

Visceral Sensory

The functional sensory branch monitoring internal organs and blood vessels, receiving stimuli such as blood pressure and visceral distension.

Somatic Motor

The functional motor branch transmitting voluntary motor output from the CNS directly to skeletal muscles.

Visceral (Autonomic) Motor

The functional motor branch transmitting involuntary motor output from the CNS to cardiac muscle, smooth muscle, and glands.

Neurons

Excitable nerve cells that transfer and process information throughout the nervous system, totaling approximately $85\text{ billion}$ in the brain alone.

Neuroglia

Supporting cells that protect and assist neurons, equal in quantity to neurons and capable of cell division (mitosis).

Soma

The cell body of a neuron that integrates information, contains the nucleus, mitochondria, Golgi, ER, and abundant ribosomes, lacks mitotic spindles (amitotic), and forms gray matter.

Dendrites

Branched extensions of a neuron that receive signals from other neurons and conduct them toward the soma.

Axon

A slender neuronal process that conducts impulses away from the soma toward another neuron or effector cell, typically wrapped in myelin.

Myelin Sheath

A fatty insulating wrap surrounding axons that speeds up nerve impulse conduction and creates white matter.

Synapse

The specialized site of chemical communication between an axon terminal and another cell, such as a neuron, muscle cell, or gland.

Synaptic Vesicles

Membrane-bound spherical packets located in the axon terminal that store neurotransmitters until an electrical action potential triggers their release via exocytosis.

Synaptic Cleft

The microscopic extracellular space between the pre-synaptic neuron terminal and the post-synaptic cell surface across which neurotransmitters diffuse.

Selective Serotonin Reuptake Inhibitors (SSRIs)

A class of pharmaceutical drugs that elevate mood by blocking the reuptake of serotonin, thereby leaving higher concentrations of serotonin in the synaptic cleft.

Acetylcholine (ACh)

A primary neurotransmitter that triggers muscle contraction and movement at neuromuscular junctions.

Dopamine

A major neurotransmitter regulating pleasure, motivation, and motor movement.

Serotonin

A neurotransmitter primarily involved in mood regulation and targeted by SSRI medications.

Norepinephrine

A major neurotransmitter that mediates the physiological fight-or-flight response.

Glutamate

A major excitatory neurotransmitter fundamentally involved in learning and memory.

Gray Matter

Nervous tissue areas composed predominantly of cell bodies, dendrites, and synapses, responsible for information integration and processing.

White Matter

Nervous tissue regions composed predominantly of myelinated axons, specialized for rapid information transport.

Interneurons

Multipolar neurons located entirely within the CNS that integrate and coordinate responses between sensory and motor neurons, making up $99\%$ of all neurons.

Astrocytes

Star-shaped neuroglial cells in the CNS whose perivascular feet interact with capillary endothelial cells to maintain the blood-brain barrier; the most abundant CNS glial cell.

Oligodendrocytes

Glial cells of the CNS that produce the myelin sheath by wrapping cytoplasmic processes around axons of several different neurons simultaneously.

Multiple Sclerosis

An autoimmune disorder where the immune system destroys oligodendrocytes, causing scarred myelin and impaired signal conduction along CNS nerves.

Microglia

Phagocytic immune cells resident in the CNS that clear cellular debris and waste, multiplying during active infections.

Ependymal Cells

Ciliated CNS glial cells that line the brain ventricles and spinal cord central canal to produce, monitor, and circulate cerebrospinal fluid (CSF).

Satellite Cells

PNS glial cells that envelop sensory neuron cell bodies in ganglia, regulating substance and nutrient exchange with their environment.

Schwann Cells

Also called neurolemmocytes, these PNS glial cells wrap around segments of peripheral axons to form the myelin sheath, with multiple cells insulating a single axon.

Glioma

A brain tumor originating from glial cells (such as astrocytomas, ependymomas, or oligodendrogliomas), made possible because glial cells retain the ability to undergo mitosis.

Epineurium

The outer sheath composed of dense irregular connective tissue enclosing an entire peripheral nerve.

Perineurium

A dense irregular connective tissue layer wrapping around individual fascicles (bundles of axons) within a nerve.

Endoneurium

A delicate layer of areolar connective tissue surrounding an individual neuron axon within a nerve.