Special Senses - Eye

eyeball contains ______ layers of tissue

3

What are the 3 layers of tissue in the eyeball

1. Fibrous

2. Vascular

3. Inner

___________ separates internal cavity into anterior and posterior segments

lens

Is fibrous layer vascular or avascular?

avascular

What type of connective tissue makes up the fibrous layer?

dense connective tissue

two regions of the fibrous layer of the eye

sclera and cornea

opaque posterior region in fibrous layer

sclera

transparent anterior 1/6 of fibrous layer

cornea

what anchors eye muscles to the eye

sclera

what bends light as it enters the eye?

cornea

dome shape lets light in to the lens

the cornea has numerious _______ receptors

pain

what do the cornea pain receptors contribute to

blinking and tearing reflexes

middle layer of eye

vascular layer

the vascular layer of the eye is also known as the

uvea

three regions of the vascular layer

choroid, ciliary body, and iris

which region is underneath the sclera in the posterior eye

choroid region

which region supplies blood to all layers of eyeball

choroid region

purpose of brown pigments in choroid region

absorbs light to prevent light scattering and visual

confusion

Ring of tissue surrounding lens

ciliary body

ciliary muscles are made out of _____ muscle

smooth

miliary muscles control ________ shape

lens

_________ holds lens in position

Ciliary zonule (suspensory ligament)

Colored part of eye

Iris

Central opening that regulates amount of light entering eye

Pupil

________ is the opening in the center of the iris

pupil

two muscles of the iris

circular (inner)

radial (outer)

circular muscles contract = _______ pupils

constrict

radial muscles contract = _______ pupils

dilate

constriction of circular muscles

Close vision and bright light

constriction of radial muscles

Distant vision and dim light

Inner layer of the eye is called the __________

retina

what are the layers of the retina

outer pigmented layer

inner neural layer

pigmented layer has _____ cell-thick lining

single

function of the pigmented layer

absorbs light and prevents scattering

stores vitamin A

cells of the neural layer

photoreceptors, bipolar cells, ganglion cells

order of light entering the eye

cornea, lens, retina, photoreceptors

Order of information processing in vision

photoreceptors, bipolar cells, ganglion cells, optic nerve, brain

2 types of photoreceptors

rods and cones

site where optic nerve leave eye

Optic disc (blind spot) because it lacks photoreceptors

peripheral vision receptors for dim light

rods

vision receptor for bright light

cones

color vision

cones

where are cones localized

Macula lutea, an oval region exactly at posterior pole

Tiny pit in center of macula with all cones

Fovea centralis

Macular Degeneration

Loss of vision in the center of the visual field due to damage of the macular lutea/fovea centralis (age related)

are rods affected in macular degernation?

no, Peripheral vision remains

dry macular degeneration

age related caused by deposits of lipids/proteins

fuzzy/distorted vision

wet macular degeneration

blood vessels growing in vision areas = damage rods and cones

blind spot in center of field of vision

What separates the eye into two segments

lens and ciliary zonule

fluid in the anterior segment of eye

aqueous humor

fluid in the posterior segment of eye

vitreous humor

both humor function to ....

transmit light and contribute to intraocular pressure

how does vitreous humor hold neural layer of retina firmly against pigmented layer

intraocular pressure

where does aqueous humor drain

sclera-cornea junction

which humor forms in embryo and lasts lifetime

vitreous humor

forms by filtration from the

capillaries in the ciliary processes

aqueous humor

Aqueous humor flows from the posterior chamber through the _______ into the anterior chamber.

pupil

how does the lens process information

changing shape to precisely focus light on retina

changes in lens with age

more dense

covex

less elastic

disease caused by clouding of lens

cataracts (more light needed to see)

Pinkeye is an injection of the

conjunctiva

The cornea is part of the

fibrous layer (outer)