The Nervous System

Neuron

A cell that carries electrical impulses throughout the body.

Meylin Sheath

The layer of lipid tissue that surrounds the axon.

Sensory Neurons (afferent)

Neurons that conduct impulses to the brain and spinal cord.

Motor Neurons (efferent)

Neurons that carry impulses from the central nervous system to muscles and glands.

Interneurons

Neurons that relay information between afferent and efferent neurons within the CNS.

Brain and Spinal cord

The two organs included in the central nervous system.

Frontal Lobe

The lobe of the cerebrum responsible for thinking, logic, and reasoning.

Parietal Lobe

The lobe of the cerebrum responsible for connecting impulses.

Temporal Lobe

The lobe of the cerebrum responsible for hearing and language.

Occipital Lobe

The lobe of the cerebrum responsible for vision.

Insula

The lobe of the cerebrum responsible for fight-or-flight and sensory processing.

Cerebellum

The part of the brain that coordinates voluntary movement, maintains balance, and maintains muscle tone.

Midbrain

The part of the brainstem that conducts impulses between higher and lower order functioning.

Pons

The part of the brainstem that connects the two halves of the cerebellum (bridge).

Medulla Oblongata

The part of the brainstem that controls breathing, heartbeat, and blood vessel walls.

Autonomic Nervous System

The nervous system that controls automatic activity, smooth and cardiac muscle, and glands in the soft body organs. Contains the parasympathetic and sympathetic nervous systems.

Parasympathetic Nervous System

The division of the autonomic nervous system that calms the body and returns it to normal functioning.

Sympathetic Nervous System

The division of the autonomic nervous system arouses the body, mobilizing it for a crisis (fight-or-flight).

Spinal Cord

The structure that extends from the foramen magnum in the skull all the way to the second lumbar vertebrae.

Stroke

A blood clot or hemorrhage to the brain causing brain damage.

Hydrocephalus

An abnormal production of cerebrospinal fluid that can cause limited brain growth.

Amyotrophic Lateral Sclerosis (Lou Gehrig's disease)

A neuron system disorder in which motor neurons are destroyed.

Paralysis

A condition caused by severing or cutting a nerve in the spinal cord.

Hemiplegia

Paralysis in half the body.

Paraplegia

Paralysis of both lower limbs.

Quadriplegia

Paralysis of all four limbs.

Eye

The organ responsible for sight.

Lens

The structure that focuses light on the retina.

Optic Nerve

The nerve that carries visual impulses from the eye to the brain.

Rods

Retinal receptors that detect black, white, and gray; necessary for peripheral and twilight vision.

Cones

Retinal receptors that are concentrated near the center of the retina and detect color.

Ear

The organ responsible for hearing and balance.

Cochlea

The structure in the ear that contains fluid and cilia that move with vibrations.

Ossicles

The bones in the inner ear (hammer, anvil, stirrup).

Semicircular Tubes

Structures in the cochlea that are responsible for our sense of balance.

Chemoreceptors

The receptors that detect chemicals used for both our sense of taste and smell.

Synapse

The space between the axon terminal of one cell and the dendrites of another.

Neurotransmitter

Special chemical messengers that transport signals across the synapse.