Nervous System Overview

Central Nervous System (CNS)

The part of the nervous system that includes the brain and spinal cord.

Peripheral Nervous System (PNS)

The part of the nervous system outside the CNS; includes sensory and motor neurons.

Afferent Neurons

Neurons that carry sensory information to the brain.

Efferent Neurons

Neurons that carry motor commands away from the brain to the muscles.

Somatic Nervous System

Part of the PNS responsible for voluntary movements.

Autonomic Nervous System

Part of the PNS that controls involuntary bodily functions.

Sympathetic Nervous System

The part of the autonomic nervous system that prepares the body for 'fight or flight' responses.

Parasympathetic Nervous System

The part of the autonomic nervous system that promotes rest and digestion.

Neuroglial Cells

Supportive cells that assist neurons in transmitting signals and maintaining homeostasis.

Astrocytes

A type of neuroglial cell that supports neurons and connects them to blood supply.

Oligodendrocytes

Neuroglial cells that produce myelin in the CNS.

Schwann Cells

Cells that produce myelin in the PNS.

Myelin Sheath

The protective covering around axons that facilitates faster signal transmission.

Action Potential

The electrical impulse that travels down an axon when a neuron is activated.

Resting Membrane Potential

The electrical charge of a neuron at rest, approximately -70 millivolts.

Depolarization

The process during action potential when the inside of the neuron becomes more positive.

Repolarization

The process of returning the membrane potential to its resting state after depolarization.

Reflex Arc

A neural pathway that mediates a reflex action.

Gray Matter

Regions of the CNS that contain neuronal cell bodies and unmyelinated axons.

White Matter

Regions of the CNS that contain myelinated axons.

Meninges

Protective membranes that surround the brain and spinal cord.

Cerebrospinal Fluid

The fluid that cushions and protects the brain and spinal cord.

Medulla Oblongata

The part of the brainstem