Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
30 Cards in this Set
- Front
- Back
Crying
|
Parasympathetic stimulation of lacrimal glands over-secreation of tears and tears spill over edge of eyelids.
|
|
Optic disc. AKA blind spot
|
Site where optic nerve exits the eyeball
|
|
Six Extrinsic Eye Muscles
|
1.) Lateral & medial rectus
2.) Superior & inferior rectus 3.) Superior & inferior obliques |
|
Sty
|
infection of the ciliary gland
|
|
Posterior segment
|
Larger; between lens and retina and filled with jelly-like substance; vitreous body - formed during embryonic life and does not undergo replacement. Contributes to intraocular pressure and prevents eyeball from collaplsing and keeps retina smoothly pressed against choroid.
|
|
Lacrimal fluid
|
Just superior and lateral to eyeball; almond size/shape; secrets: lacrimal fluid - serous sol. of salts/mucous/lysozyme; lubricates/cleans/moistens eyeball
|
|
Fovea centralis
|
Small depression in center of macula lutea contians cones only that are not covered by bipolar and ganglion cells; area of highest visual acuity or resolution.
|
|
Lacrimal apparatus
|
Group of structures that produce/drain tears, AKA lacrimal fluid.
|
|
Macula lutea
|
Exact center of postior portion of retina
|
|
Macular degeneration
|
New blood vessels grow over macula lutea and distorted vision and blindness results.
|
|
Anerior Segment
|
Anterior to lens; further divided into: anterior chamber - behind cornea/in front of iris filled with serous fluid; aquous humor- formed from blood capillaries in ciliary process; undergoes contant replacement and helps noursih cornea and lens. Forms intraocular pressure, approx. 16 mm Hg, that, along with vitreous body; maintains eyeball shape; keeps retina smoothly pressed against choroid for an even surface for reception of clear images
|
|
Wall of the Eyeball
|
Fibrous tunic: superficial, avascular wall
Cornea: anterior; avascular; transparent membrane covering colored iris; is curved to help focus.refract (bend) light. Sclera, AKA "white of the eye": dense CT covering all of th eyeball rigid, fiving it shape; protects inner parts |
|
Opthalmoscope
|
medical instrument to look through pupil to see a magnified image of the posterior wall (fundus of the retina and its anterior blood vessels) (to view pathological changes, as wth HTN or DM)
|
|
Vascular Tunic AKA Uvea
|
Middle wall
a.) Choroid: posterior portion; highly vascular - provides nutrients to posterior retina b.) Ciliary Body: anterior extension of choroid c.) Ciliary process: internal folds that secrete serous aqueous humor d.) ciliary muscle: band of smooth muscle that alters shape of lens |
|
Vascular Tunic - Iris
|
Flat, donut-shaped, colored portion of eyeball; suspended between cornea & lens; attached at outer margin to ciliary process; regulates the amount of light entering eyeball through the pupil
|
|
Lens
|
Just posterior to the pupil and iris, avascular; transparent; consists of onion-layered proteins.
Function: focus/refract light rays for clear vision. |
|
Vascular Tunic - Pupil
|
Opening/hole in center of iris. Bright light of parasympathetic stimulation, pupil constriction dim light of sympathetic stimulation, pupil dilation
|
|
Conjunctiva
|
Thin, proctective mucous membrane; lines from inner aspect of eyelids onto anterior eyeball
a.) palpebral - lines the inner eyelid b.) bulbar/ocular- lines the outer eyeball c.) bloodshot eyes - dilated blood vess. of conjunctiva on eyeball. d.) conjunctivitis, AKA pinkeye - inflammation of conjunctive usually caused by bacteria; sometimes caused by an irritant (dust, smoke, pollution) |
|
Accommodation of the lens
|
Increase in convex curvature of the lens (ant. and post. surface) for near vision.
Presbyopia - with aging, lens loses elasticity and its ability to accommodate. |
|
Physiology of Vision
|
Visual transduction of light into an electrical signal.
1. Absorption of light by photopigments in rods and cone (photoreceptor). a.) Photpigment = colored proteins in rods/cones that undergo structural changes when they absorb light. i.) Rhodopsin - the single photopigment in rods. ii.) Three different photopigment for three different types of cones (color blindness: due to absence of the cone photopigment sensitive to red or green light). b.) All photopigment contain: i.) Opsin - a glycoprotein; 4 diffe. types - 1 for each photopigment and each type (due to variations of a.a. sequences) abosrbs different wavelengths of incoming light. ii.) retinal a vitamin A derivative; the light- absorbing portion (night blindness - inability to see will at low light levels; caused by a long- term deficiency of vitamin A and decreases amounts of retinal. c.) When light is absorbed, retinal changes shape (isomerization) and seperates for opsin (AKA bleaching); (in darkness, it is converted back to its original shape). d.) decreased release of an inhibitory neurotransmitter, blutamic acid, thereby exciting the bipolar cells that synapse with rods. Bipolar cells that synapse with cones may be excited or inhibited by light. e.) Excited bipolar cells synapse with, and, excite ganglion cells, which become depolarized and initiate nerve impulses f.) ganglion cells leave retina as optic (II) nerve fibers, optic chiasm, optic tract, thalamus, primary visual area of occipital lobe of cerebral cortex. |
|
Detached retina
|
Trauma, eye disorders, detachment between neural layer and pigment layer, fluid accumulates and distorted vision and or blindness results.
|
|
Constriciton of the pupil
|
Autonomic reflex prevents light rays from entering the eye through the periphery of the lens.
|
|
Refraction of light rays
|
75% bu cornea and 25% by lens (for fine-tuning)
Normal - can refract light rays from an object 6 m/20 ft away. Myopia, AKA nearsightedness - image focused in front of retina. Hyperopia, AKA farsightedness - image focused behind retina. Astigmatism - irregularities on surface of cornea of lens prevent image from being focused on retina. |
|
Eyelashes
|
Project from antierior border of each eyelid & Eyebrows- runtransversely above upper eyelids.
Function: protect eyeballs from foreign objects, sweat, direct sunlight Ciliary (sebaceous) glands - at base of eyelashes' hair follicles; secrete lubricating fluid into follicles. |
|
Sensory Tunic AKA Retina
|
Innermost wall; has tow layers:
1.) Pigmented Layer (nonvisual); contains melanin; absorbs stray light. 2.) Neural Layer (visual); multilayered outgrowth of th ebrain; 3 layers of retinal neurons to process visual input from external to internal: I.) Photoreceptor layer - two types a.) rods b.) cones II.) Bipolar cell layer III.) Ganglion cell layer |
|
Glaucoma
|
Increased intraocular pressue and degeneration of the retina usually resulting in blindness.
|
|
Excretory lacrimal ducts
|
6 - 12 ducts that drain tears from glands onto conjunctiva of upper eyelid; tears pass medially over anterior eyeball.
|
|
Eyelids
|
Upper and lowe- consist of Epith. tissue/CT/Muscle tissue.
Functions: a.) protects eyes from excessive light & foreign objects b.) lubricate eyeballs c.) shade eyes during sleep |
|
Cataract
|
Loss of transparnecy of lens due to aging, injury, UV light exposure, drugs (steriods), other ds.'s (DM) and leading cause of blindness
|
|
Superior & Inferior lacrimal puncta
|
2 small openings at medial eye; tears pass into: Superior & inferior lacrimal canals - drains tears into a lacrimal sac which stores and drains tears into the nasolacrimal duct - carries tears into nasal mucosa (cold) which could cause a blockage and cause watery eyes.
|