Nervous System Module 6

Vocabulary terms and definitions covering the functions, anatomy, and signal transmission processes of the human nervous system based on module study notes.

Neurons

Nerve cells that serve as the basic unit of function in the nervous system.

Glia

Cells that nourishment and support neurons.

Integration

The process where the CNS processes incoming sensory information, compares it with past experiences, and determines an appropriate response.

Axon Hillock

The region where the cell body transitions into the axon; the site where the action potential is initiated.

Sensory Neuron (Afferent Path)

Neurons that take information from sensory receptors to the CNS along the afferent pathway.

Interneuron

Neurons located completely within the CNS (brain or spinal cord) that connect sensory and motor neurons.

Motor Neuron (Efferent Path)

Neurons that take information away from the CNS to an effector (muscle or gland) along the efferent pathway.

Myelin Sheath

A white lipid coating made by Schwann cells that electrically insulates axons and facilitates signal transmission.

Nodes of Ranvier

Gaps in the myelin sheath that allow nerve conduction to occur faster.

Synapse

A specialized area where information transfer happens between neurons; they are separated by the synaptic cleft and do not physically touch.

Neurotransmitters

Signal chemicals stored in synaptic vesicles in axon terminals that transfer information across the synaptic cleft.

Synaptic Integration

The process where the sum of excitatory and inhibitory signals received by a neuron determines whether it will fire an action potential.

GABA

The main inhibitory neurotransmitter in the CNS.

Glutamate

The main excitatory neurotransmitter in the CNS.

Norepinephrine

A neurotransmitter involved in alertness, arousal, and the stress response.

Action Potential

A nerve impulse within a neuron occurring as a result of changes in electrical charge across the axon's plasma membrane.

Depolarization

A stage of the action potential where sodium ions rush into the neurons, making the inside more positive.

Repolarization

A stage of the action potential where potassium ions exit the neurons, restoring the negative charge.

Refractory Period

A brief period after an action potential when the neuron cannot fire again.

Somatic Afferent

Sensory signals from the skin, muscles, joints, and special senses.

Visceral Afferent

Sensory signals from body organs.

Somatic Efferent

Motor signals to skeletal muscles; voluntary movement and reflexes.

Autonomic Efferent

Motor signals to glands, smooth muscle, and cardiac muscle; involuntary movement.

Sympathetic Division

The "fight or flight" division of the autonomic nervous system that coordinates stress responses.

Parasympathetic Division

The "rest and digest" division of the autonomic nervous system that counters the sympathetic system and returns housekeeping functions to normal.

Enteric Nervous System

A subdivision of the autonomic nervous system that controls digestion independently of the CNS.

Cranial Nerves

Nerves that extend from the brain, consisting of 12 pairs.

Spinal Nerves

Nerves that arise from the spinal cord, consisting of 31 pairs.

Spinal Reflex Arc

An automatic path involving the spinal cord and spinal nerves that responds quickly to a stimulus without conscious thought.

Gray Matter

Nervous tissue made of cell bodies and non-myelinated axons.

White Matter

Nervous tissue made of myelinated axons.

Cerebrospinal Fluid (CSF)

Fluid that cushions and protects the CNS and circulates between meninges and brain ventricles.

Ventricles

Four interconnected chambers in the brain that produce and circulate cerebrospinal fluid.

Meninges

Three layers of protective membrane around both the brain and the spinal cord.

Dura Mater

The outermost, thick, and tough layer of the meninges.

Arachnoid Mater

The spider-like middle layer of the meninges where CSF circulates in the subarachnoid space.

Pia Mater

The innermost, delicate, and translucent layer of the meninges attached to the surface of the brain and spinal cord.

Blood-Brain Barrier

A highly selective semipermeable border made of epithelial cells linked by tight junctions that separates circulating blood from the brain.

Cerebrum

The largest region of the brain, consisting of 4 lobes, controlling voluntary movement and higher functions like speech and thought.

Arbor Vitae

The tree-like pattern of white matter found within the cerebellum.

Cerebellum

Brain region lying under the occipital lobe that maintains posture, balance, and coordination.

Ascending Tracts

Pathways in the spinal cord that carry sensory information from the body to the brain.

Descending Tracts

Pathways in the spinal cord that carry motor commands from the brain to the body.