Nervous System Overview

The nervous system detects changes (stimuli), processes information, and initiates responses.

The brain and spinal cord; the control center of the body.

Nerves outside the CNS; carries information to and from the CNS.

Nerves that carry impulses to the CNS.

Nerves that carry impulses away from the CNS.

Part of the motor division that controls voluntary movement of skeletal muscles.

Part of the motor division that controls involuntary functions (smooth muscle, cardiac muscle, and glands).

A specialized cell that transmits neural impulses.

Nerves that carry signals away from the central nervous system (CNS) to the muscles and glands.

12 pairs of nerves that mostly serve the head and neck; most are mixed, but three are sensory only

31 pairs of nerves, all mixed, serving the rest of the body.

Inflammation of the nerves, caused by infection, compression, or trauma.

A type of neuritis affecting the sciatic nerve, causing pain in the thigh and leg.

Progressive brain neuron deterioration, causing memory loss, disorientation, and mood swings.

Partial paralysis and sometimes mental retardation caused by brain damage during prenatal development.

Disorder of brain blood vessels, often caused by blood clots, aneurysms, or hemorrhages.

Degeneration of the myelin sheath surrounding neuron processes in the CNS, leading to hardened sheaths.

Permanent loss of motor control, caused by damage to the CNS.

The ear is divided into three areas, the Outer Ear, the Middle Ear, and the Inner Ear.

The auricle, or pinna, is the visible part of the ear that helps collect and focus sound waves into the ear canal.

The tympanic membrane, or eardrum, is a thin membrane that vibrates when sound waves hit it, transferring the vibrations to the middle ear.

The three ossicles, the malleus, incus, and stapes, are the smallest bones in the body and are responsible for transferring and amplifying sound vibrations from the eardrum to the inner ear.

Perilymph is a fluid that fills the space between the bony labyrinth and the membranous labyrinth of the inner ear. Endolymph is a thicker fluid found inside the membranous labyrinth.

A group of sensory receptors that detect stimuli related to touch, pressure, temperature, and pain. These senses are found throughout the body, primarily in the skin.

A specialized group of senses that include vision, hearing, taste, smell, and balance. These senses are concentrated in specific organs and provide detailed information about the environment.

Sensory receptors that detect changes in temperature, allowing us to sense heat and cold.

Sensory receptors that respond to mechanical pressure or movement. They are responsible for senses like touch, pressure, and vibration.

Mechanoreceptors located deep in the skin, tendons, and ligaments. They are sensitive to deep pressure and vibrations.

Mechanoreceptors located near the surface of the skin. They are sensitive to light touch and vibrations.

Sensory receptors that detect chemical stimuli. They are responsible for taste and smell.

Groups of taste cells located on the tongue that detect different tastes like sweet, sour, salty, and bitter.

The organ inside the cochlea responsible for hearing, containing hair cells that convert sound vibrations into nerve impulses.

A flexible membrane lining the bottom of the organ of Corti, receiving vibrations from the oval window and transferring them to the tectorial membrane.

A gel-like membrane inside the organ of Corti that vibrates due to the basilar membrane's movements, bending the hair cells.

Sensory receptors inside the organ of Corti, located below the tectorial membrane. Their bending by the tectorial membrane generates nerve impulses.

The sense of balance when the head is stationary, maintained by the utricle and saccule within the vestibule.

The sense of balance during movement, maintained by the semicircular canals, keeping you oriented during turns and rotations.

The organ of static equilibrium located within the utricle and saccule, containing hair cells embedded in an otolithic membrane.

Tiny calcium carbonate stones within the otolithic membrane of the macula, moving with head movements to bend hair cells.

The process by which the lens changes shape to focus light on the retina for close and distant objects.

Bending of light as it passes through different mediums, like the cornea and lens in the eye.

The transparent, outermost layer of the eye. It helps focus light rays.

The colored part of the eye that controls the amount of light entering the pupil.

The black opening in the center of the iris that allows light to pass through.

The transparent structure behind the pupil that helps focus light on the retina.

Muscle attached to the lens that controls its shape for accommodation.

The light-sensitive layer at the back of the eye that converts light into nerve impulses.

Light-sensitive cells in the retina that detect different types of light, responsible for dim light and color vision.

Nerve that carries nerve impulses from the eye to the brain for interpretation.

Loss of hearing, either partial or complete.

Deafness due to damage to the cochlea or auditory nerve.

Deafness due to damage to the eardrum or ossicles.

Disorder of the inner ear causing dizziness, nausea, tinnitus, and hearing loss.

Nausea caused by repetitive stimulation of the equilibrium receptors in the inner ear.