Term
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Definition
Palpebrae.
Upper and lower.
Shades eyes during sleep.
Protects from light and foreign objects.
Spreads lubricating sections over eyes. |
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Definition
Secretes material that lubricates the eye.
Is on the underside of the eyelid. |
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Definition
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Definition
Protect eyes
Move and prevent substances from entering the eye.
Protect against foreign objects, perspiration. |
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Term
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Definition
| Infection of gland of follicle of eyelash. |
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Term
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Definition
| System containing the structures for tear production and drainage. |
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Term
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Definition
Located in the superior lateral region of the orbital
Secretes tears.
Tears carried to conjunctiva and passed to eyeball. |
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Term
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Definition
Located in the maxilla bone.
Collects tears.
Drains into the nasal cavity.
Tears drained via duct system to nasal cavity. |
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Term
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Definition
Parasympathetic stimulation.
Over secretion of tears. |
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Term
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Definition
Protect
clean
Lubricate/moisten
surface of the eye |
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Term
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Definition
6 muscles.
Move the eyeball.
Motor units are small. |
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Term
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Definition
Three layers:
Fibrous tunic
Vascular tunic
Retina |
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Term
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Definition
Outermost/superficial layer.
Two regions:
Sclera: white portion, majority, thick, gives shape/structure to eyeball.
Cornea: Clear layer, involved in focusing light, covers iris. |
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Term
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Definition
Presence of a lot of blood vessels.
Three components:
Choroid: lines the sclera, helps with structure, contains blood vessels.
Ciliary body: secretes aqueous humor, contains smooth muscle tissue, changes lens shape, consists of ciliary processes.
Iris: Smooth muscle tissue,pigmented, consists of circular and radial smooth muscle that regulate the amount of light entering through the pupil. |
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Term
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Definition
Called the neural tunic.
Location of photoreceptors.
Inner lining.
Beginning of visual pathway.
Consists of pigment epithelium and neural portion.
Has optic disk and fovea centralis. |
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Term
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Definition
Landmark where optic nerves exit the eyeball.
Where optic nerves and bloodvessels are in contact with the eyeball.
Blind spot. |
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Term
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Definition
Area of highest visual activity.
Has a lot of photoreceptors.
Contains only cones.
Light is perceived best when projected on this region. |
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Term
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Definition
In the retina.
Absorbs stray light and maintains sharp image. |
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Term
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Definition
In the retina.
Consists of three layers:
Photoreceptor cells.
Bipolar Neurons.
Ganglion neurons.
These three form the optic nerve.
Light passes through all three layers of the neural portion to reach the photoreceptors. |
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Term
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Definition
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Term
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Definition
| Exact center of the poterior of the retina. |
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Term
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Definition
Flexible protein structure.
Avascular.
Transparent normally.
Composed of protein called crystallin.
Enclosed in a capsule.
Held in place by suspensory ligaments.
Function: fine tune focusing of light rays onto retina. |
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Term
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Definition
We change the shape of the lens.
Gets fatter or thinner depending on the distance away from the object.
Visual activity depends on flexibility of the lens.
Closer the light the longer the focal distance.
The rounder the lens the shorter the focal distance. |
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Term
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Definition
Area in front of the lens.
Contains aqueous humor:
watery fluid which contributes to intraocular pressure, nourishes the lens and cornea, constantly replaced. |
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Term
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Definition
Area behind the lens.
Contains vitreous humor:
contributes to intraorbital pressure, holds retina against choroid, formed during embryonic development, phagocytes remove debris. |
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Term
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Definition
Sensitive to wavelengths of light.
Stimulated when light waves hit the cell.
Visual pigments inside the cell determine sensitivity.
Inner segment: nucleus and organelles.
Outer segment: in contact with pigment epithelium, named for shape of the cell, contain visual pigment. |
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Term
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Definition
Contain rhodospin.
Sensitive to wide rage of wavelengths.
Most active in dim light.
When stimulated we see light. |
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Term
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Definition
Contain various pigments.
Color vision
Require more intense light to be stimulated.
When stimulated we see color.
Color blind people do not have functional cones. |
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Definition
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Term
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Definition
| Region of electromagnetic spectrum to which our eyes are sensitive. |
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Definition
| Particle measurement of light energy. |
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Term
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Definition
Light sensitive pigments.
Breakdown when exposed to light. |
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Term
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Definition
Visual pigment of rods.
Breaks down to opsin and retinal when exposed to light.
Cones have modified versions of rhodopsin. |
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Term
| PHOTORECEPTORS IN THE DARK |
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Definition
Na+ channels are open.
Allows for a constant flow of calcium into the cell.
Neurotransmitter is released to inhibit bipolar cells.
No AP through the pathway. |
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Term
| PHOTORECEPTORS IN THE LIGHT |
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Definition
Breakdown of rhodopsin causes Na+ channels to close.
Closing of Na+ channels stops release of neurotransmitter.
Bipolar cells not inhibited so AP is propogated to the ganglion cells and along visual pathway. |
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Term
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Definition
Changing the shape of the lens to focus.
As we age degree of acommodation decreases. |
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Term
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Definition
Ciliary muscles contracted lens rounded for close vision.
Ciliary muscles relaxed lens is flattened for distant vision. |
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Term
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Definition
Near sightedness.
Can focus close up but cant see things far away.
Can be due to flexibility of the lens or shape of the eyeball. |
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Term
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Definition
Less common.
Far sightedness.
Can't see up close
Due to concave nature of lens.
Eye must change shape to view things at close proximity or increase curvature of lens. |
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Term
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Definition
| Farsightedness due to aging. |
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Term
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Definition
Medial movement of the two eyeballs so that they are both directed at the same object.
Binocular vision. |
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Term
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Definition
Optic nerve carries AP from the retina.
At optic chiasma some neurons decussate.
Each hemisphere receives AP from the medial half of view from same side and later half of field of view from opposite side |
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Term
| VISUAL AP CONDUCTED TO BRAIN |
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Definition
Neurons conducted to thalamus's later geniculate nucleus.
Some to superior colliculate of midbrain (reflex activity)
Some synapse with neurons that extend to cerebrum (perceive light) |
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