The Nervous System

Nervous System

The ultimate control center of the body overseeing all communication among organ systems.

Neurons

Excitable nerve cells that respond to stimuli by conducting impulses to transmit signals.

Neuroglia

Supportive cells in nervous tissue that provide nutrition, insulation, and assist in signal transmission.

Multipolar Neurons

Neurons with more than 3 processes (1 axon and 2 or more dendrites); 99% of neurons are multipolar.

Afferent Neurons

Sensory neurons that transmit information from sensory receptors to the CNS.

Efferent Neurons

Motor neurons that transport information from the CNS to the rest of the body.

Cerebrum

The largest part of the brain, responsible for learning, speech, emotion, reasoning, vision, and hearing.

Cerebellum

Part of the brain that maintains posture and balance and coordinates smooth movements.

Brainstem

The base of the cerebrum that relays information between the brain and spinal cord and coordinates automatic functions.

Somatic Nervous System

Part of the PNS that controls voluntary movements by innervating skeletal muscles.

Autonomic Nervous System

Part of the PNS controlling involuntary movements of the heart, lungs, stomach, etc.

Parasympathetic Division

Part of the autonomic nervous system that conserves energy and maintains digestion, often called the 'rest and digest' division.

Sympathetic Division

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

Reflex Arc

A neural pathway that controls reflex actions, consisting of a receptor, sensory neuron, integration center, motor neuron, and effector.

Myelin Sheath

The protective covering over long axons that insulates them and increases the speed of nerve impulse transmission.

Nodes of Ranvier

Unmyelinated gaps in the myelin sheath that aid in increasing the velocity of nerve signal conduction.

Astrocytes

Glial cells that maintain the blood-brain barrier and provide structural support and regulation of ion/nutrient concentrations.

Oligodendrocytes

CNS cells that myelinate axons and provide structural framework.

Microglial Cells

CNS cells that remove debris and pathogens through phagocytosis.

Dendrites

Extensions from the neuron cell body that receive signals.

Axon Terminals

The end of an axon that releases neurotransmitters when a nerve impulse is received.