Eye ball Flashcards
What is the job of the sense organs
carry out messages about external/internal enviroment to central nervous system
What is a stimulus
A stimulus is a source of energy converted from one form to another
What are sensory receptors
They are the modified ends of sensory neurons that are activated by specific stimuli
When does sensory adaptation happen
occurs when you have adjusted to a change in the enviroment
What are the types of receptors
-Photoreceptors(vision-rods and cones)
-Chemoreceptors(taste buds, nose, internal sense(blood pH))
-Mechanoreceptors(Proprioceptors&touch(skin), hearing, balance and body position)
-Thermoreceptors(temperature- sking, heat and cold receptors)
What are the three layers of the eye structure
- Sclera- outermost layer, covered by a cornea
- Choroid- middle layer that has pigments that prevent scattering by absorbing stray light
- Retina- innermost layer, composed of three layers of cells(Bipolar cells, Light sensitive, optic nerve cells_
What are the 3 cells that make up the retina
Light sensitive- Rods and cones
Bipolar cells- pass message from rods and cones to cells of optic nerve
Optic nerve cells- ganglion cells
What is the iris
coloured muscle regulating the amount of light entering the eye; opening for light to go in
What do the lens do
focuses image on the retina by action of doral and ventral ciliary muscles
What does the vitreous humor do
cloud, jellylike material maintains eye shape and lets light through
What is the difference between rods and cones
Rods: are used in dim lighting
Cones: used for identifying colors(red, blue & green cones)
What is the fovea centralis
closely packed with cones at the center of the retina, most sensitive area of the eye
What are the blind spots
lack of rods and cones where the optic nerve comes in contact with the retina
accommodation
adjustments made to lens and pupil to view near or far objects
Focusing for distant vision and close vision
LOOK AT NOTES AND TEXTBOOKS
cataracts and its solutions
-Lens or cornea becomes clouded
Solutions
- replace cloudy lens with plastic one
-remove lens and …..
What is astigmatism
abnormal curvature of the cornea or surface of lens
what is nearsightedness
(myopia) image is focused in front of the retina
Solution- glasses with concave lens
What is farsightedness
(hyperopis) image is focused beyond the retina
Solution- glasses with a convex lens
WHat is color blindess
inherited condition where one lacks certain cones(r,b, or g)
What is the sclera
-tough outer covering
-it is protection
Cornea
Transparent portion of sclera
-allows light entry into eye, bends light(refract)
Aqueous humor
clear liquid
-fills cavity between lens and cornea; provides nutrients and produces cornea
Choroid
absorbs light rays(pigmented)
-contains blood vessels that nourish the eye
