• A nerve cell that is the fundamental functional unit of the nervous system.
• excitable cells that contribute to the highly specialized cell function of transmission of nerve impulses throughout the body.

Filled with cytoplasm and contains processes, including the nucleus, that support the metabolic demands of the cell.

Multiple, branched extensions of the cell body that transmit impulses to the cell body.

Carries impulses away from the cell body.

Enhances transmission speed of nerve impulses from the dendrites to the synaptic terminals and is interrupted by the nodes of ranvier.

Carry signals away from the spinal cord and brain to targets in the body that regulate activity.

• Most abundant neuron type
• Provide connections between neurons, transmitting signals between afferent and efferent neurons

• Greek meaning "glue"
• Neural support cells that provide support and nutrition, maintain homeostasis, and form the myelin that covers the neurons of the brain.

Responsible for the formation pf multilayered myelin segments around multiple axons in the brain, promoting the speed of nerve impulse conduction in the CNS

Produce myelin on long, single axons of the peripheral nervous system

Nodes that are rich in sodium channels and are necessary to promote the movement of the nerve impulse over long distances

A process in which impulses traveling down the axon jump from node to node in a stepwise fashion

• Neurons communicate with other neurons and cells in the body through the generation of electrical signals
• Electrical events that travel along the entire neuron by allowing charged ions to flood through channels in the semipermeable membrane around the nerve cell

The difference in electrical charge between the inside and outside of the cell

The point at which the cell is committed to an action potential.

The point at which the axon is joined to the cell body

1. Resting membrane potential:
• The membrane potential of a cell at rest
• The membrane potential (or state of tension) inside a cell membrane, measured relative to the fluid outside in the absence of significant electrical activity
2. Depolarization phase:
• The result of rapid movement of sodium into the cell through sodium channels in the cell membrane
• This inflow generates an electrical impulse which is transmitted along the axon to trigger the release of neurotransmitters
3. Repolarization phase:
• Is initiated by the flow of potassium ions out of the cell
• The efflux of potassium ions promotes return of the cell to RMP

A small gap or junction separating neurons

• Transmit impulses by passage of current-carrying ions through small openings known as gap junctions
• Is fast, direct and multidirectional
• Gap junctions are commonly involved in the transmission of electrical impulses that lead to cardiac contractions

Involve specific structures important for impulses stimulated by neurotransmitters, chemical agents affecting the funtion of other nearby cell or cells.

Changes membrane potential toward the point of threshold potential (less negative), promoting the excitatory effect of propagation of the impulse or neuron firing.

Has the opposite effect of moving the membrane potential away from threshold (more negative), promoting an inhibitory effect

1. Amino acids (e.g., glutamic acid and gammaaminobutyric acid [GABA])
2. Peptides (e.g., endorphins, enkephalins, substance P)
3. Monoamines (e.g., serotonin, dopamine, norepinephrine)

• Released from axon terminals
• Can alter the effect of neurotransmitters
• May inhibit, potentiate, or prolong the effects of neurotransmitters

Chromatolysis

The swelling of a neuron because of injury

Phagocytosis and inflammatory responses caused by a dead neuron damaging neighboring cells

Distinctive structures formed in the nucleus or cytoplasm

1. Frontal: reasoning, planning, speech, and movement
2. Parietal: perception of touch, pressure, temperature, and pain
3. Temporal: perception, memory, and recognition of auditory stimuli
4. Occipital: Vision

• Left:
• Speech and language
• Calculations
• Math
• Logical abilities
• Right:
• Visual imagery
• Face recognition
• Music
• Special abilities

The extension of nerves branching from the spinal cord below the lumbar and sacral levels before exiting the vertebral column.

• Dorsal horns: posterior extensions which contain sensory neurons that receive afferent impulses via the doral roots
• Ventral horns: The anterior extensions which contain efferent motor neurons that leave the cord through the ventral roots
• Upper motor neurons (UMNs): include cell bodies in the motor cortex and the axons extending to the brainstem and spinal cord.
• Lower motor neurons (LMNs): located in the ventral horns of the spinal cord,

• Comprised of the axons in the descending coricospinal and corticobulbar tracts
• Provides control of voluntary movement

• Separate from the pyramidal motor system
• Modulates motor function
• Attenuating erratic motions and maintaining muscle tone and stability of the trunk

• A cerebral arterial structure that connects the vertebral and carotid circulations
• Is important as a route of collateral circulation in case perfusion is impaired in another arterial system

• Protects the brain from exposure to potentially hazardous substances by reduced permeability in capillaries that supply the brain
• Transports substances in a selective manner because of the tight junctions in the endothelial cells lining the capillaries of the brain
• Does not allow transport of large molecules, molecules with low lipid solubility, and molecules with high electrical charge
• Does allow transport of substances that are small, highly lipid soluble, and have a low electrical charge
• Functions include:
• Protection of the brain from foreign substances
• Protection of the brain from hormoned and neurotransmitters in the systemic circulation
• Protection against drastic environmental fluctations

Formed when astrocytes and microglia combine

Occurs when there is inadequate blood supply to meet the needs of the brain tissue

The main excitatory neurotransmitter in the body, active in the promotion of many higher-organ functions

• Decerebrate posturing: The result of increased extensor muscle excitability
• Decorticate posturing: the result of increased flexor muscle excitability

Edema of the optic disc

An interconnection of fibers formed by spinal nerves

Group of nerve cell bodies

Axon fibers extending from cell bodies in either the brain or spinal cord that project to an autonomic ganglion

Fibers projecting from the autonomic ganglion to a target organ

A basic functional pathway of the nervous system that represents the process by which stimuli are received and interpreted, and in turn stimulate a response.

Occurs when the injury affects cells in distal areas of the body, such as the hands and feet

Occurs when axonal degeneration occurs because of damage to the cell body

Occurs when degeneration of the axon is caused by a crushing injury

The clinical manifestations of damage to peripheral nerves

Occurs when nerve trauma is limited to a single area

• Peripheral nerve damage involving multiple axons
• Can occur secondary to disease processes such as multiple sclerosis, diabetes mellitus, nutrient deficiency, and toxic agents (arsenic)

trauma to the brachial nerve plexus resulting in flaccid paralysis of the affected arm

Disorders which involve brain structures with the exclusion of the motor neurons, motor cortex, and pyramidal tract (corticobulbar and corticospinal)

Inability to coordinate muscle activity

Involuntary movements of flexion and extension, pronation and supination of hands, toes and feet; slow, writhing-type movements

Jerking, swinging, sweeping motions of the proximal limbs

Decrease in spontaneity and movement

Irregular, spasmodic, involuntary movements of the limbs or facial muscles, often accompanied by hypotonia

Resistance to movement; rigidity decreasing to stiffness after movement begins

Abnormal tonicity; difficulty maintaining posture

Excessive motor activity

Repeated, habitual muscle contractions; movements that can be voluntarily suppressed for short period only

Oscillating, repetitive movements of whole muscles; irregular, involuntary contractions of the opposing muscle

Inability of muscles to relax

Inability to control muscle movement

Inability to control balance and coordination

• Are limited to the originating hemisphere and can involve either motor or sensory brain components
• Symptoms are sensory and sutonomic without promoting an altered state of consciousness
• Short lived, lasting a few seconds

• Involve both hemispheres and result in loss of consciousness and lack of memory about events during and after seizure
• Short lived, lasting a few minutes

Caused by a more generalized electrical transmission

• Characterized by a brief change in level of consciousness (LOC) and eye and mouth movements
• Can occure up to 100 times a day

Are characterized by involuntary muscle movements of the extermeties or body, and are not associated with LOC

• Convulsive and associated with tonic or clonic motions.
• Tonic: A state of continuous muscle contraction
• Clonic: Rapid successions of alternating muscle contraction and relaxation

Physical state after recovery from seizure; manifested by extreme fatigu, headach, muscle pain, and weakness

Brain disorder

1. Relapsing-remitting (RR): charcaterized by periods of acute neurologic symptoms (flare-ups, exacerbations, relapses) alternating with periods of symptom relief or return of neurologic function (remissions)
2. Primary Progressive: slow, chronic deterioration of neurologic function not associated with exacerbations or remissions
3. Secondary progressive: Initially presenting with RR characteristics of exacerbations and remissions, followed by a pattern of slow, chronic deterioration as seen in primary progressive
4. Progressive relapsing: Steady progression of a decline in neurologic function also associated with exacerbations and possible remissions

• Uncontrollable laughing or crying
• Can result from cerebral involvement, leading to altered control of emotional responsiveness

Irregular eye movements

Considered to be 15 mm Hg or 150 to 200 mm H2O

Involved in the detection of neurotransmitters to control release and flow of impulse through the neuron