Medical Terminology Nervous

Neuron

A specialized nerve cell that receives, processes, and transmits electrical signals.

Neurotransmitter

A chemical messenger released by neurons to communicate with other cells.

Synapse

The junction where communication occurs between a neuron and another cell.

Axon

The part of a neuron that carries impulses away from the cell body.

Dendrite

A branch-like part of a neuron that receives signals.

Myelin sheath

A fatty insulating covering around some axons that speeds nerve impulse transmission.

Schwann cell

A cell in the peripheral nervous system that produces myelin around axons.

Action potential

A rapid electrical change that travels along a neuron.

Depolarization

The phase of an action potential when the inside of a neuron becomes less negative, mainly due to sodium entering.

Repolarization

The phase when the neuron returns toward its resting electrical state, largely involving potassium leaving.

Sodium-potassium pump

A membrane protein that actively transports sodium out of cells and potassium into cells.

Central nervous system (CNS)

The brain and spinal cord.

Peripheral nervous system (PNS)

All nerves outside the brain and spinal cord.

Somatic nervous system

The part of the PNS involved in voluntary movement and sensory information.

Autonomic nervous system

The part of the nervous system controlling involuntary functions.

Sympathetic nervous system

The autonomic division responsible for the "fight-or-flight" response.

Parasympathetic nervous system

The autonomic division responsible for "rest-and-digest" functions.

Cerebrum

The largest part of the brain; responsible for conscious thought, sensation, memory, and voluntary movement.

Cerebellum

The brain region responsible for coordination, balance, posture, and fine motor control.

Brainstem

The part of the brain connecting the brain to the spinal cord; controls many vital functions.

Medulla oblongata

A brainstem region controlling vital functions such as breathing, heart rate, and blood pressure.

Pons

A brainstem structure involved in breathing, sleep, and communication between brain regions.

Hypothalamus

A brain region regulating temperature, hunger, thirst, hormones, and homeostasis.

Thalamus

A brain structure that relays most sensory information to the cerebral cortex.

Corpus callosum

A bundle of nerve fibers connecting the left and right cerebral hemispheres.

Frontal lobe

The brain lobe involved in reasoning, planning, speech production, personality, and voluntary movement.

Parietal lobe

The brain lobe involved in touch, pressure, temperature, pain, and spatial awareness.

Temporal lobe

The brain lobe involved in hearing, memory, language comprehension, and emotion.

Occipital lobe

The brain lobe primarily responsible for vision.

Meninges

Three protective membranes surrounding the brain and spinal cord.

Cerebrospinal fluid (CSF)

Fluid that cushions and protects the brain and spinal cord.

Blood-brain barrier

A protective barrier that limits which substances can enter brain tissue from the blood.

Stroke

A disruption of blood flow to the brain caused by a clot or bleeding.

Ischemic stroke

A stroke caused by blockage of blood flow to part of the brain.

Hemorrhagic stroke

A stroke caused by bleeding in or around the brain.

Transient ischemic attack (TIA)

A temporary interruption of blood flow to the brain that causes stroke-like symptoms without permanent brain injury.

Seizure

Abnormal, uncontrolled electrical activity in the brain.

Epilepsy

A neurological disorder characterized by recurrent unprovoked seizures.

Meningitis

Inflammation of the meninges, commonly caused by infection.

Encephalitis

Inflammation of brain tissue, often caused by infection.

Concussion

A mild traumatic brain injury caused by a blow or jolt that disrupts normal brain function.

Alzheimer disease

A progressive neurodegenerative disorder causing memory loss and cognitive decline.

Parkinson disease

A progressive neurological disorder involving loss of dopamine-producing neurons and causing movement problems.

Multiple sclerosis (MS)

An autoimmune disease in which the immune system damages myelin in the CNS.

Amyotrophic lateral sclerosis (ALS)

A progressive disease that damages motor neurons, causing muscle weakness and loss of movement.

Huntington disease

An inherited neurodegenerative disorder causing involuntary movements and cognitive/psychiatric changes.

Bell palsy

Sudden weakness or paralysis of one side of the face, usually involving the facial nerve.

Neuralgia

Nerve pain.

Neuropathy

Damage or dysfunction of nerves, often causing pain, numbness, or weakness.

Aphasia

Impaired ability to understand or produce language, usually due to brain injury.

Ataxia

Loss of coordination or balance.

Paralysis

Loss of muscle function in part or all of the body.

Hemiplegia

Paralysis affecting one side of the body.

Syncope

Temporary loss of consciousness caused by reduced blood flow to the brain; fainting.

Dementia

A general term for significant decline in memory and cognitive abilities that interferes with daily life.