Definition Flashcards
peripheral nervous system PNS
Communication between the central nervous system, and the rest of the body is accomplished by the PNS
Forms the communication networks between the central nervous system CNS and the rest of the body.
consists of the nerves that branch out from the brain and spinal cord, which communicate with the rest of the receptors, muscles, and glands.
receptors
Are sensory nerve endings that respond to stimuli
Are sensory nerve endings that respond to various kinds of stimulation. The awareness that results in what we know as sensation.
sense organs
The eyes, ears, skin, mouth, and nose—have receptors that detect sensations. Then sensory neurons transmit the signals to the CNS, where they are interpreted as a sight, hearing, touch, taste, or smell.
five special sense organs
eyes, ears, skin, mouth, and nose
sense organs (like the eye for example)
contain receptors that are activated by specific stimuli. This initiates nerve impulses that lead to the brain (the optic nerve). The brain interprets the signal.
How light is transmitted to the brain
Light———— receptor cells in the eye
(Stimulus) (sense organ)
—-optic nerve ———brain translate
stimuli into visual images
Eyes
-are paired organs of sight (right eye, OD; left eye, OS; each eye, OU). Several accessory structures (muscles, eyelids, and eyebrows, for example) are associated with the eyes.
Pupil
Small, round dark circle structure, located in the center of the eye
light first enters the eye through the pupil.
Light rays enter the pupil, the small, dark circle structure located in the center of the eye that is surrounded by the colored portion of the eye that we regularly see, the iris.
Iris
The colored portion of the eye that surrounds the pupil. muscles of the iris constrict the pupil in bright light and dilate the pupil in dim light, therefore regulating the amount of light entering the eye.
Selera
The tough outer layer of the eye, the light or peak membrane covering most of the eyeball.
scleritis
means inflammation of the sclera; however, sclerose means to harden or to cause hardening.
Associate with your certain accessory organs
muscle, fascia, eyebrow, eyelid, conjunctiva, and the lacrimal glands.
conjunctiva
Lines the inner surface of the eyelid
is the mucous membrane lining the inner surface of the eyelid an acts as a protective covering for the exposed surface of the eye.
lacrimal gland
Produce and store tears (lacrimal fluid)
lacrimal fluid
tears that keep the eyelids moist
tears produced by the lacrimal gland wash over the eyeball and are drained through small openings in the inner corner of the eye. Tears pass through these openings into small lacrimal ducts that drain into the nasolacrimal sac. From here the tears pass into the large nasolacrimal duct that ends in the nasal cavity. If more tears are produced than can be removed, we say the person is crying. This is also called tearing.
Eyeball
Is composed of three layers:
1) sclera: The tough outer layer that covers most of the eye.
2) cornea: the transparent structure at the front of the eyeball that bends or refracts light rays so that they are focus properly on the sensitive receptor cells in the posterior of the eye.
3) choroid: dark brown membrane inside the sclera; it is continuous with the iris and the ciliary body it is continuous with the iris and the ciliary body
Sclera
The tough outer layer that covers most of the eye.
White opaque membrane covering most of the eyeball
Cornea
Transparent structure at the front of the eye that refracts light rays
The transparent structure at the front of the eyeball that bends are refracts light rays so that they are focused properly on the sensitive receptor cells in the posterior of the eye.
Choriod
A dark brown membrane inside of the sclera.
Is a vascular layer of tissue that supplies blood to the outer retina
ciliary body
surrounds the outside of the lens and causing flattening or thickening of it
Is on the anterior surface of the eye
surrounds the outside of the lens in a circular fashion, allowing change in shape and thickness of the lens.
Also secretes a fluid called aqueous humor
Refraction of light rays
The changes in the shape and thickness of the lenses bring about refraction of light rays
Changes in the posterior region of the eye, causing flattening of the lens (for distant vision) or thickening and rounding of the lens ( for close vision).
accommodation
Refractory adjustment for close vision
Ability of the eye to adjust to variations in distance
aqueous humor
A fluid that is secreted from the ciliary body, which is found in the anterior chamber
Vitreous chamber
Cavity of the eye, which is filled with a soft jelly-like material, the vitreous humor.
Vitreous humor
Soft jelly-like material that fills the vitreous chamber
Escape of this fluid, due to trauma, may result in significant damage to the eye