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special senses eye
Question | Answer |
---|---|
three layers (tunics) of the eye | 1.fibrous tunic, 2.vascular tunic 3.sensory tunic |
outermost layer of the eyeball: | fibrous tunic |
what is the purpose of the fibrous tunic? | serves as protective coat for the more sensitive structures beneath. |
fibrous tunic is comprised of: | sclera & cornea |
the sclera or "white of the eye" provides: | strength, shape, and structure to the eye |
the sclera passes in front of the eye to become: | the cornea |
the cornea allows: | light to enter the interior of the eye. |
the cornea does not contain capillaries. It relies on __________ for nourishment | eye fluids |
a thin membrane called ____________ covers the outer surface of the eye and lines the eyelids. | conjunctiva |
the middle layer of the eyeball is called the _________ or ___________ | vascular tunic or uvea |
the uvea consists of the ____________, ___________ & ___________. | choroid, iris, and ciliary body |
the _________ provides the blood supply for the entire eye. | choroid |
the choroid contains pigmented cells that: | prevent extraneous light from enetering the eye |
An opening in the choroid allows: | the optic nerve to enter the inside of the eyeball. |
The anterior portion of the choroid contains two modified structures : | iris and ciliary body |
The iris is: | colored, contractile membrane |
the perforated center of the iris is called: | pupil |
The iris regulates: | the amount of light passing through the pupil to the interior of the eye |
As environmental light increases, the pupil __________, as light decreases, the pupil ________ | constricts, dilates |
A circular muscle that produces aqueous humor: | ciliary body |
the ciliary body is attached to: | a capsular bag that holds the lens between the suspensory ligaments |
As the ________ ___________ contracts and relxes, it alters the shape of the lens making it thicker or thinner | ciliary muscle |
changes in the shape of the lens allow the eye to focus on an image | accommodation |
the innermost layer: | sensory tunic |
the sensory tunic is: | delicate, double-layered retina |
retina consists of: | thin, outer pigmented layer lying over the choroid and a thick, inner nervous layer (visual portion) |
the retina is responsible for: | reception and transmission of visual impulses to the brain |
retina has two types of visual receptors: | rods and cones |
_______ function in dim light and produce black-and-white vision | rods |
__________ function in bright light and produce colour vision | cones |
in the central portion of the reina is a highly sensitive structure called the: | macula |
in the center of the macula is the: | fovea |
when the eye focuses on an object, light rays from that object are directed to the: | fovea |
because the fovea is composed of only _______(cones/rods) that lie very close to each other, it provides the greates acuity for colour vision | cones |
rods and cones contain a chemical called: | photopigment or visual pigment |
what happes when light strikes the photopigment? | a chemical change that stimulates rods and cones |
light striking the photopigment creates a chemical change that pruduces impulses that are transmitted through the ______ _______ to the ________, where they are interpreted as vision | optic nerve / brain |
the optic nerve and blood vessels of the eye enter at the: | optic disk |
the center of the optic disc is referred to as the ________ _______ because the area has neither rods nor cones for vision. | blind spot |
this fluid (humor) is found in the posterior chamber and anterior chamber of the anterior segment and provides nourishment for the lens and the cornea. | aqueous humor |
aqueous humor is produced by the _________ ______. | ciliary body |
small opening that allows drainage of aqueous humor from the eye | canal of Schlemm |
if aqueous humor fails to drain from the eye at the rate it is produced, a condition called _________ results. | glaucoma |
a jellylike substance that fills the interior of the eye (vitreous chamber) | vitreous humor |
refractive structures of the eye, focusing light rays sharply on the reina (3): | vitreous humor, lens, & aqueous humor |
adnexa of the eye include: | all supporting structures of the eye globe |
the superior, inferior, lateral, and medial rectus as well as the superor and inferior oblique are the _________ ________ | extraocular muscles |
the 6 extraocular muscles control: | movement of the eye |
lying superior to the outer edge of each eye are the: | lacrimal glands |
produce tears that bathe and lubricate the eyes: | lacrimal glands |
tears coolect at the inner edges of the eyes called the ________, and pass through pinpoint openings the ________ _________ to the mucus membranes that line the inside of the ________ _________. | canthi (singular, canthus); lacrimal glands; nasal cavity |