Nervous System Vocabulary Flashcards

Vocabulary flashcards covering the divisions of the nervous system, glial cells, neuron structures, channel types, receptor mechanisms, and neurodegenerative disorders based on lecture material.

Neurons

Masses of nerve cells that serve as the functional unit of the nervous system and transmit information.

Cell Body

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

Dendrites

Shorter, numerous processes of a neuron that receive incoming information.

Axons

Single long nerve fibers that conduct information away from the neuron cell body.

Central Nervous System (CNS)

The major division of the nervous system consisting of the brain and spinal cord.

Peripheral Nervous System (PNS)

The major division of the nervous system consisting of all neural tissue outside the CNS, including 31 pairs of spinal nerves and 12 pairs of cranial nerves.

Somatic Nervous System

The division of the PNS that controls the voluntary actions of skeletal muscles.

Autonomic Nervous System

The visceral motor division of the PNS that controls involuntary actions of smooth muscle, cardiac muscle, and glands.

Enteric Nervous System

A division of the PNS located in the walls of the digestive tract that controls smooth muscle and glandular tissue independently of the CNS.

Parasympathetic Division

The branch of the autonomic nervous system that promotes 'rest and digest' housekeeping functions and reduces overall energy usage.

Sympathetic Division

The branch of the autonomic nervous system that mobilizes body systems during activity, driving the 'fight or flight' response.

Astrocytes

Star-shaped CNS glial cells that connect blood vessels to neurons, regulate extracellular chemical concentrations, and contribute to the blood-brain barrier.

Oligodendrocytes

CNS glial cells with processes that wrap around axons to create myelin sheaths for insulation.

Microglia

Small CNS glial cells that perform immune surveillance and phagocytosis to digest cellular debris and pathogens.

Ependymal Cells

Ciliated CNS glial cells lining the ventricular system that filter blood to create and circulate cerebrospinal fluid (CSF).

Satellite Cells

PNS glial cells found in sensory and autonomic ganglia that surround and support neuron cell bodies.

Schwann Cells

PNS glial cells that insulate nerve fibers by wrapping around a portion of a single axon segment to form myelin.

Gray Matter

Nervous tissue composed of unmyelinated structures and neuron cell bodies (termed nuclei in the CNS and ganglia in the PNS).

White Matter

Nervous tissue composed of bundles of myelinated axons (termed tracts in the CNS and nerves in the PNS).

Afferent Neurons

Sensory neurons that gather information from receptors and transmit impulses into the central nervous system.

Interneurons

Neurons located entirely within the CNS that process, interpret, and connect sensory inputs to appropriate motor outputs.

Efferent Neurons

Motor neurons that convey impulses out of the CNS to effectors such as muscles or glands to produce a response.

Unipolar Neurons

Exclusively sensory neurons featuring a single axon emerging from the cell body that splits to span long distances, with cell bodies located in ganglia.

Bipolar Neurons

Neurons with two distinct processes (one axon and one dendrite) extending from opposite ends of the cell body, found in the olfactory epithelium and retina.

Multipolar Neurons

Neurons that possess one axon and two or more dendrites, representing the vast majority of neurons in the body.

Voltage-gated Channels

Transmembrane ion channels that open or close in response to alterations in membrane potential.

Stretch-gated Channels

Ion channels that open or close in response to mechanical tension applied directly to the cell membrane.

Ligand-gated Channels

Transmembrane ion channels that open or close when a specific chemical ligand binds to the channel protein site.

Ionotropic Receptors

Ligand-gated ion channel receptors that induce fast, short-lived changes in ion movement across the postsynaptic membrane.

Metabotropic Receptors

G protein-linked receptors that trigger intracellular second messenger cascades, leading to slower and longer-lived postsynaptic responses.

Agonist

A molecule that binds to a receptor and activates it, producing the same functional effect on the postsynaptic neuron as the endogenous neurotransmitter.

Antagonist

A molecule that occupies a receptor without activating it, thereby blocking receptor activation by agonists or neurotransmitters.

Amyotrophic Lateral Sclerosis (ALS)

A progressive neurodegenerative disorder marked by the degeneration of motor neurons in the spinal cord and brain.

Myasthenia Gravis

An autoimmune disorder in which circulating antibodies destroy neuromuscular connections, impairing muscle stimulation.

Multiple Sclerosis (MS)

An autoimmune inflammatory demyelinating disease of the CNS in which myelin sheaths are degraded and replaced by scar tissue (sclerosis).