79 terms

Ch. 08 - The Special Senses

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Accessory structures of the eye that are not directly related to the sense of vision.
Eyebrows, Eyelids, and Conjuctiva
Shades the eyes from sunlight and prevent perspiration from reaching the eyes.
Eyebrows
Protects the eyes from foreign objects and to prevent desiccation of the eyes by lubricating fluid.
Eyelids
A mucous membrane on the inner lining of eyelids, which produces lubricating and cleansing fluid for the surface of eye.
Conjuctiva
Exocrine glands that secretes a dilute saline solution called tears for moistening the eyes.
Lacrimal Glands
Contains mucus, antibodies and antibacterial enzymes that protect the eye from infections.
Tears
Contains enzymes that seem to help reduce stress levels.
Emotional tears
Layers of tissue of the eyeball wall.
Fibrous Tunic, Vascular Tunic, and Sensory Tunic
Outermost layer of the eyeball wall made of the fibrous connective tissue with minimal blood vessels.
Fibrous Tunic
2 regions of the Fibrous Tunic.
Sclera and Cornea
A white area in the Fibrous Tunic that extends to the back of the eye towards the front.
Sclera
A transparent tissue in the front eye for allowing light to enter the eyeball.
Cornea
Another name for Vascular Tunic.
Uvea
Middle layer of the eye made of thin fibrous connective tissue that contains numerous blood vessels (capillaries).
Vascular Tunic
Structures in the Vascular Tunic in the eye.
Choroids, Iris, Ciliary Body, Suspensory Ligaments, Lens, and Pupil.
A pigmented membrane in the back to provide nutrition and to absorb light.
Choroid
Regulates the amount of light entering the eye by constriction and dilation.
Iris
Regulates the shape of the Lens.
Ciliary Body
Attaches the Ciliary Body to the Lens.
Suspensory Ligaments
Transparent tissue that bends the light entering the eye.
Lens
Opening created by the actions of the Iris where a large pupil is caused by dilated Iris, while a small pupil is created by constricted Iris.
Pupil
Another name for the Sensory Tunic
Retina
Innermost layer of the eye made of specialized nerve tissues.
Sensory Tunic
layers of tissues in the Sensory Tunic.
Outer Pigmented Layer and Inner Neural Layer
Layer which absorbs light and stores vitamin A.
Outer Pigmented Layer
Layer that detects light using photoreceptors and sends nerve impulses to the occipital lobe of the cerebrum through the optic nerves.
Inner Neural Layer
Types of photoreceptors are found on the Neural Layer.
Rods and Cones
Photoreceptors that detect tones of visual images.
Rods
Photoreceptors that detect colors.
Cones
Functions of the Cornea.
Light transmission and Refraction
Functions of the Ciliary Body and Iris.
Accommodation and controls light intensity.
Function that changes the shape of the Lens.
Accomodation
Function of the Sclera
Protection
Function of the Choroids
Blood supply and pigments prevent reflection
Function of the Retina
Photoreception and Impulse Transmission
Convex
Thicker
Concave
Thinner
Diaphragm of the camera.
Iris of the eye.
Compound Lens of the camera.
Curved Cornea and the Biconvex Lens of the eyes
Film of the camera
Retina of the eye
Camera lens moves back and forth for sharp focusing.
Ciliary Muscles changing lens curvature
The bending of light as it passes between two transparent substances.
Refraction
Necessary to form a small-sized inverted image on the retina.
Refraction
Refractory media structures
Cornea and Lens
Lens shape for distant vision. Sympathetic input relaxes the ciliary muscle tightening the ciliary zonule flattening the lens.
Concave Lens
Lens shape for close vision. Parasympathetic input contracts the ciliary muscle loosening the ciliary zonule bulging the lens.
Convex Lens
As the distant object moeves closer, the image move behind the retinal to keep the image sharply on the retina.
Accomodation
Ciliary muscles contract, lens ligaments (suspensory) relax, lens becomes rounder (more convex).
Close Vision
Ciliary muscles relax, lens ligaments (suspensory) contract, lens becomes less convex (concave).
Distant Vision
After age 55, accommodation is no longer possible.
Presbyopia
During accommodation, the iris also constricts to narrow the pupil, permitting increased depth of focus.
Pupil Constriction
The movement of each eyeball is controlled by six eye muscles that allow the eye to follow a moving object.
Convergeance
Muscle that contract to decrease pupil size; Parasympathetic
Sphincter Pupillae
Muscle that contract to increase pupil size; Sympathetic
Dilator Pupillae
Muscles of the Iris
Sphincter Pupillae and Dilator Pupillae
Muscle that rotates the eye up and in; innervates the Occulomotor (III) nerve.
Superior Rectus
Muscle that rotates the eye down and in; innervates the Occulomotor (III) nerve.
Inferior Rectus
Muscle that rotates the eye inward; innervates the Occulomotor (III) nerve.
Medial Rectus
Muscle that rotates the eye out; innervates the Abducens (VI) nerve.
Lateral Rectus
Muscle that rotates eye down and out; innervates the Trochlear (IV) Nerve.
Superior Oblique
Muscle that rotate eye up and out; innervates the Occulomotor (III) nerve.
Inferior Oblique
Fibers that release acetylcholine to contract the ciliary muscles, which relax the lens for sharp focusing, these nerves stimulate the iris to constrict the pupil.
Parasympathetic Fibers
Fibers release norephiephrine to stimulate the iris to dilate the pupil.
Sympathetic Fibers
Layer of tissue in the eye that contain rods and cones.
Retina
Photoreceptor neurons that synapses with rods and cones.
Bipolar Cells
Photoreceptor responsible for colorless vision in relatively dim light.
Rods
Photoreceptor provides color vision and function in day light.
Cones
A light sensitive pigment in the rods; decomposes in the presence of light and triggers a complex series of reactions that initiate nerve impulses on the optic nerve.
Rhodopsin
Sets of cones that provide color vision.
Red, Blue, and Green
cells that are inhibitory in the eye.
Bipolar Cells
2 substances created from photodissociation of Rhodopsin When light strikes the rods.
Retinene and Opsin
What happens to Rhodopsin in the Rods in a dark room?
More Rhodopsin are produced
What makes the eye sensitive to when Rhodopsin is increased in the rods?
Light
Photoreceptors that provide black and white vision under low light intensity.
Rods
What happens to rods and cones when exposed to higher intensity light?
Rods are bleached out and the cones provide color vision.
In the dark, a constant movement of Na+ into the rods produces what?
Dark current
What happens to rhodopsin molecules in the dark?
Rhodopsin are stable and signals Na+ channels to stay open.
When inflow of Na+ in the dark, what happens to the rods and their synapses?
Depolarizes
What activates the inhibitory bipolar cells?
Depolarized rods