Overview of the Nervous System and Related Disorders

Brain

Central organ of the nervous system, controlling most bodily functions and processing sensory information.

Cerebrum

Largest part of the brain; responsible for thinking, memory, and voluntary movement.

Nerve

A bundle of axons in the peripheral nervous system that transmits signals.

Neuron

A nerve cell that transmits signals; the basic structural and functional unit of the nervous system.

Cell body (soma)

Central part of a neuron containing the nucleus and organelles.

Neuroglia

Supporting cells of the nervous system that protect and nourish neurons.

Synapse

The gap between neurons where messages are passed chemically or electrically.

Axon

A long fiber that carries impulses away from the neuron's cell body to other neurons or muscles.

Axon Terminal

End of an axon that releases neurotransmitters to send signals across a synapse to other neurons or effectors.

Dendrite

Branchlike extensions of a neuron that receive impulses and carry them to the cell body.

Neurotransmitter

Chemical messenger released by neurons to transmit signals across a synapse.

Myelin sheath

A fatty covering around some axons that increases the speed of impulse transmission.

Schwann Cells

PNS cells that form the myelin sheath around axons.

Node of Ranvier

Gaps between sections of the myelin sheath that speed up nerve impulse conduction.

Stimulus

Any change in the environment that elicits a response in the nervous system.

Blood-Brain Barrier (BBB)

A protective barrier that restricts the passage of substances from the blood into the brain tissue.

Central nervous system (CNS)

Includes the brain and spinal cord; processes information and issues instructions.

Peripheral Nervous System (PNS)

All nerves outside the CNS connect the brain/spinal cord to the body.

Motor/Efferent Nerve

A motor neuron that carries impulses away from the CNS to muscles or glands.

Afferent neuron

Sensory neuron that carries impulses toward the central nervous system (CNS).

Somatic Nervous System (SNS)

Part of the nervous system controlling voluntary muscles/movements of skeletal muscles.

Autonomic nervous system (ANS)

Controls involuntary bodily functions like heart rate and digestion.

Parasympathetic Nervous System

Part of the autonomic system that controls rest and digestion.

Sympathetic division

Part of the autonomic nervous system that triggers the "fight or flight" response.

Spinal Cord

Long bundle of neurons running down the back, transmitting signals between the brain and body.

Cerebrospinal Fluid (CSF)

Clear fluid surrounding the brain and spinal cord, providing cushioning and nutrients.

Meninges

Three protective membranes (dura mater, arachnoid mater, pia mater) that cover the brain and spinal cord.

Seizure (Sz)

Sudden, uncontrolled electrical brain disturbance.

Stroke

Sudden loss of brain function due to blood flow disruption.

Coma

State of deep unconsciousness where a person is unaware of surroundings.

Symptoms (Sx)

Patient-experienced signs of a disease or condition.

Electroencephalography (EEG)

Test measuring brain's electrical activity.

Positron Emission Tomography (PET)

A scan showing organ function using a radioactive tracer.

Computed Tomography (CT)

Imaging scan using X-rays for detailed body images.

Lumbar Puncture (LP)

Procedure to collect cerebrospinal fluid from the spinal canal.

Electromyography (EMG)

A test that records electrical activity in muscles.

Magnetic Resonance Imaging (MRI)

Imaging scan using magnets and radio waves.

Magnetoencephalography (MEG)

Brain activity mapping using magnetic fields.

Intracranial Pressure (IP)

Pressure within the skull that can affect brain function.

Spinal Cord Injury (SCI)

Damage to the spinal cord resulting in loss of function (mobility/sensation).

Myasthenia Gravis (MG)

Chronic autoimmune disorder causing weakness in skeletal muscles.

Huntington's Disease (HD)

A genetic disorder causing movement, cognitive, and psychiatric symptoms.

Chronic Traumatic Encephalopathy (CTE)

Brain degeneration linked to repeated head trauma.

Guillain-Barré Syndrome (GBS)

An autoimmune disorder where the immune system attacks peripheral nerves.

Alzheimer's Disease (AD)

A progressive disorder causing memory loss and cognitive decline.

Multiple Sclerosis (MS)

An Autoimmune disease where the immune system damages nerve coverings.

Parkinson's Disease (PD)

Disorder causing tremors, stiffness, and balance issues.

Traumatic Brain Injury (TBI)

Brain dysfunction caused by external force.

Transient Ischemic Attack (TIA)

Temporary blood flow blockage in the brain ("mini-stroke").

Cerebral Palsy (CP)

Group of disorders affecting movement and posture due to brain damage.

Subarachnoid Hemorrhage (SAH)

Bleeding between the brain and its covering tissues.

Amyotrophic Lateral Sclerosis (ALS)

Disease causing loss of voluntary muscle control.