exercise 22: vision

an opening located in the center of the eye

pupil

the pupil is surrounded by a colored __

iris

the white of the eye

sclera

the sclera is covered by a membrane called the ___, which continues under the eyelids

conjunctiva

the eyes come together at the ___ and ___ commissure

lateral and medial commissure

small piece of tissue near the medial commissure called the ___ _____

lacrimal caruncle

the sclera is a protective layer for the eye, but also is the attachment point for the muscles of the eye and helps maintain ____ ____

intraocular pressure

the appearance of your eyes being bloodshot is caused by blood vessels dilating _____

anteriorly

the sclera is continuous with the ___ of the anterior eye, and both of them together form the ___ ___ of the eye

cornea, fibrous tunic

what are lacrimal secretions

tears

what part of the lacrimal apparatus is located laterally and superiorly to the eye

lacrimal gland

what does the lacrimal gland do

secrete tears to protect the eye

where does the fluid drain to in the eye

nasolacrimal duct

the first layer covering the sclera (white part) is the

conjunctiva

the conjunctiva is composed of what tissue

epithelial tissue

in the center of the eye is the

cornea

what does the cornea do

bends light rays to allow us to focus light

what is the cornea made of

dense connective tissue

where are the posterior and anterior chambers located in the eyes

in front of and behind the iris.

what are the anterior and posterior chambers filled with

aqueous humor

where is aqueous humor made

ciliary body

a few millimeters of aqueous humor are produced each day, and all of it is absorbed by the ___ ____ ___ (canal of schlemm)

scleral venous sinus

the ___ is what gives our eyes color

iris

the __ ____ of the iris constrict in bright light, reducing the diameter of the ____

sphincter pupillae, pupil

the ___ ____ muscles constrict in dim light, increasing the diameter of the ___

dilator pupillae, pupil

behind the pupil is the ___, which is made of a crystalline protein

lens

the ___ ___ contracts to make the ______ ____ that attach to the lens loosen, which decreases the pull on the lens. this makes the lens more round, and allows for focusing on closer images

ciliary muscle, suspensory ligaments

behind the lens is the ___ ___

vitreous chamber

this compartment occupies most of the posterior portion, or FUNDUS, of the eye

vitreous chamber

what is the vitreous chamber filled with. this fluid maintains the shape of the eyeball

vitreous humor

the vitreous chamber is composed of three layers:

fibrous tunic, vascular tunic, nervous tunic

this tunic consists of the choroid, the ciliary body, and the iris

vascular tunic

this tunic contains the retina

nervous tunic

a pigmented, vascular layer in the vascular tunic

choroid

blood vessels found in this layer nourish the eye, and the pigmentation prevents light from scattering and blurring vision

vascular layer

the layer closest to the vitreous humor is the

nervous tunic

this structure has an outer pigmented layer to prevent light scattering, and also has an inner neural layer that can turn light into action potentials

retina

the sclera is also the ___ tunic

fibrous

what are the three layers of the retina

ganglionic, bipolar, and photoreceptive layers

what layer of the retina is composed of rods and cones

photoreceptive layer

___are important for determining the shape of something and for seeing in dim light

rods

___are involved in color vision and visual acuity (determining fine detail)

cones

what is at the center of the macula

fovea centralis

region where the concentration of cones is the greatest

fovea centralis

the minimum distance an object can comfortably be held in focus is called the

near point

a ten year old may be able to focus ___ - ____ cm away

8-10cm

a 65yo may not be able to even focus closer than ___ - ___cm away

80-100cm

this type of vision allows animals to perceive depth

binocular vision

a phenomenon where the cornea or lens is not perfectly smooth

astigmatism

another name for hyperopia

farsightedness

the eyeball is short and the image is focused posterior to the retina

farsightedness

another name for myopia

nearsightedness

in ____, the eyeball is long and lenses with negative diopters focus the images farther back on the retina

nearsightedness

what are the three separate cone sensitivities that color vision depends on

red, green, and blue sensitivities

changes in the genes on the _ chromosome are the most common cause of color blindness

X

after looking at a bright object or light against a dark background, then one closes their eyes, they can still see a light object in a dark background. this is called an ____ ____

after image

the ____ is due to the photoreceptors in the eye continuing to fire

afterimage

what happens after an afterimage occurs?

a negative afterimage (opposite of afterimage occurs)

what is the photosensitive pigment of the eye called

rhodopsin

what is rhodopsin made up of

retinal (vitamin A) and a protein called opsin

when light strikes the retina, the purple colored rhodopsin splits into its two components and becomes pale. this is called:

bleaching

the ____ disc is a region where the retinal nerve fibers exit from the back of the eye and from the optic nerve

optic

the optic disc is also known as the

blind spot