Anatomy - The Eye

Light is radiated in waves called _________

"photons"

describe the two cavities of the eye...

1. Anterior- filled with aqueous humor that is produced by the choroid plexuses and drained by the Canal ofSclemm: in front of lens. 2. Posterior- filled with a jelly-like vitreous humor that is formed in the embryonic stage; behind lens.

Before light can reach the rods and cones of the retina, four things must occur:

1. Cornea and lens must refract light to retina 2. Accomodation of the lens- to adjust for near and far focus ( ciliary muscles & suspensory ligaments) Near- thick lens ( muscle contracts) Far- thin lens ( muscle relaxes) 3. Constriction of Pupil- light control 4. Convergence of two eyeballs to focus on an object by extrinsic muscles

describe the eye muscles

1. Extrisinsic- outside, voluntary, move the eyeball 2. Intrinsic-inside,involuntary . Iris=opens and closes pupil regulating size Ciliary muscles= controls shape of lens to accommodate for near/far focusing

Our receptors are stimulated by light wavelengths in the visible spectrum...what area of the wavelength

400- 700nm

Loss of lens transparency is referred to as A) a cataract. B) glaucoma. C) myopia. D) accommodation. E) corneal scarring.

A) a cataract.

The space between the iris and the cornea is the A) anterior chamber. B) posterior chamber. C) pupil. D) aqueous humor. E) vitreous body.

A) anterior chamber.

A sudden flash of bright light would A) cause contraction of the pupillary constrictor muscles. B) cause contraction of the pupillary dilator muscles. C) cause relaxation of the ciliary body. D) cause relaxation of the ciliary ligaments. E) increase the size of the iris.

A) cause contraction of the pupillary constrictor muscles

Rhodopsin is found in A) rods. B) cones. C) visual pigments. D) sodium pumps. E) neurotransmitters.

A) rods.

When viewing an object close to you, your lens should be more A) rounded. B) flattened. C) convex. D) lateral. E) medial.

A) rounded.

Night blindness can be treated by administering A) vitamin A. B) vitamin D. C) vitamin E. D) vitamin K. E) vitamin C.

A) vitamin A.

The lens of the eye thickens when the A) conjunctiva contracts. B) ciliary muscles relax. C) ciliary muscles contract. D) ciliary processes contract. E) suspensory ligaments pull on the lens.

B) ciliary muscles relax.

The ciliary muscle helps to A) control the amount of light reaching the retina. B) control the shape of the lens. C) control the production of aqueous humor. D) move the eyeball. E) both A and B

B) control the shape of the lens.

The transparent portion of the eye is the A) conjunctiva. B) cornea. C) iris. D) pupil. E) canthus.

B) cornea.

The anterior cavity is A) hollow. B) filled with aqueous humor. C) filled by the vitreous body. D) filled with perilymph. E) filled with endolymph.

B) filled with aqueous humor.

There are three different types of cones, each one sensitive to a different color wavelength of light. These cones are designated A) red, yellow, and blue. B) red, blue, and green. C) red, green, and yellow. D) yellow, green, and blue. E) red, yellow, and indigo.

B) red, blue, and green.

The lens focuses light on the photoreceptor cells by A) moving up and down. B) moving in and out. C) changing shape. D) opening and closing. E) dilating and constricting.

C) changing shape.

The shape of the lens is controlled by the A) pupillary constrictor muscles. B) pupillary dilator muscles. C) ciliary muscles. D) suspensory ligaments. E) aqueous body.

C) ciliary muscles.

The pigmented portion of the eye is the A) conjunctiva. B) cornea. C) iris. D) pupil. E) canthus.

C) iris.

Which of the following extrinsic eye muscles is responsible for rotating the eye laterally? A) inferior rectus B) inferior oblique C) lateral rectus D) medial rectus E) superior rectus

C) lateral rectus

Treatment of a cataract usually involves removal of the A) cornea. B) iris. C) lens. D) sclera. E) vitreous humor.

C) lens.

Which of the following is part of the inner tunic of the eye? A) lateral rectus muscle B) iris C) retina D) sclera E) conjunctiva

C) retina

A blind spot in the retina occurs where A) the fovea is located. B) ganglion cells synapse with bipolar cells. C) the optic nerve attaches to the retina. D) rod cells are clustered to form the macula. E) amacrine cells are located.

C) the optic nerve attaches to the retina.

found in the Vascular or Middle Tunic

Choroid- brown pigment Ciliary body- muscle that controls lens shape; aqueous humor Iris Pupil

found in the outer fibrous tunic layer of the eye

Comea- transparent (fibrous tissue) Sclera- White portion ( dense fibrous tissue) Canal ofSchlemm- drainage of humor

give more detail about cones

Concentrated in small depression called the "fovea" in macula \utea at center of retina . Bright light vision . Color vision . Sharpness of image

The lacrimal glands A) are located in pockets in the frontal bones. B) produce most of the volume of tears. C) produce a slightly acidic secretion that contains lysozyme. D) A and B only E) all of the above

D) A and B only

Normal eye focusing is termed A) hyperopia. B) myopia. C) presbyopia. D) emmetropia. E) refraction.

D) emmetropia.

When all three cone populations are stimulated, one sees A) red. B) blue. C) green. D) white. E) black.

D) white.

What do the rods and cones do?

Detect photons

The fibrous tunic of the eye A) consists of the sclera and the cornea. B) provides mechanical support and some protection for the eye. C) serves as a point of attachment for extrinsic eye muscles. D) A and C only E) all of the above

E) all of the above

Visual acuity is also known as A) nearsightedness. B) farsightedness. C) myopia. D) astigmatism. E) clarity of vision.

E) clarity of vision.

what are the accessory structures of the eye?

Eyelashes. Eyebrows. Eyelids. Lacrimal Ducts

Three layers of the eye

I. Fibrous or Outer Tunic: 2. Vascular or Middle Tunic: 3. Nervous Tunic- Retina:

Physiology of sight

I. Light enters the pupil 2. Image formed on the retina 3. Rods and Cones get excited and generate action potential Rhodopsin undergoes structural change This triggers a chain of enzymatic reactions Enzymatic reactions cause changes in the permeability of the neuron membrane causing it to go from polarized to depolarized 4. Imbalance of the ions produces a "signal" in the bipolar cells 5. Excitatory signal transmits to ganglion cells 6. Ganglion cells transmit impulse through optic nerves 7. Impulses meet at optic chiasma 8. Impulse sent to occipital lobe for interpretation

Three layers of the retina

I. Photoreceptorlaver- generatesaction potential; made of rods and cones 2. Bipolar laver- transmits impulse 3. Ganglion cells- relays message to optic nerve and then to occipital lobe

Is a cone-shaped cavity in the front of the skull that contains the eyeball.

Orbit

describe the rods

RODS: . Found around periphery ( 120 million) . Light and dark discrimination. Dim light vision Shape and movement

Contains rods & cones; allows us to see color.

Retina

what is the function of the eye?

The eye converts light energy into electrical nerve impulses(photoreceptors) that is in turn interpreted by the brain ( occipital lobe) as sight.

accommodation

ability to focus for close vision (under 20 ft)

what are the Two Cavities of the eye?

anterior posterior

Fluid in the anterior segment that provides nutrients to the lens & cornea.

aqueous humor

fills anterior and posterior chambers of the anterior cavity of the eye

aqueous humor

astigmatism

blurred vision, resulting from unequal curvatures of the lens or cornea

Drains the aqueous humor of the eye.

canal of schlemm

Nutritive (vascular) layer of the eye.

choroid

posterior five-sixths of middle (vascular) tunic

choroid coat

Contains muscle that controls the shape of the lens.

ciliary body

causes lens to change shape

ciliary muscles

ligament that attaches the lens to the ciliary body.

ciliary zonule

cataract

clouding of the lens, resulting in loss of sight

glaucoma

condition of increasing pressure in the eye, resulting from blocked drainage of aqueous humor

neurons in the retina that are responsible for color vision

cones

inner lining of eyelid

conjuctiva

Most anterior part of the sclera-your "window on the world"

cornea

transparent anterior portion of outer tunic

cornea

refractory media of the eye

cornea, aqueous humor, lens, vitreous humor

list the structures and fluids through which light passes as it travels from the cornea to the retina

cornea...aqueous humor..pupil of iris...lens...vitreous humor...retina

separation of the retina from the choroid layer of the eye

detached retina

Attached to the eyes are the ____ muscles that allow us to direct our eyes toward a moving object.

extrinsic

The anterior aspect of each eye is protected by the ____, which have eyelashes projecting from their edges.

eyelids

area of acute or discriminatory vision.

fovea centralis

hyperopia

inability to focus well on close objects; farsightedness

night blindness

inability to see well in the dark; often a result of vitamin A deficiency

found in the Inner or Nervous Tunic

inner layer of the eye containing the retina functioning in image formation

the retina is the ___ ___ of the eye

inner tunic

Pigmented "diaphragm" of the eye.

iris

smooth muscle that controls light entering the eye

iris

The anterior part of the choroid forms these two structures

iris & ciliary body

secretes tears

lacrimal glands

refraction

light bending

convergence

medial movement of the eyes during focusing on close objects

myopia

nearsightedness

emmetropia

normal vision

A protein component of photopigment

opsin

Area of retina that lacks photoreceptors.

optic disk

area where optic nerve meets eye

optic disk

Name in sequence the neural elements of the visual pathway, beginning with the retina and ending with the optic cortex. Retina--________--________--__________ Synapsein thalamus --__________--Optic cortex

optic nerve optic chiasma optic tract optic radiation

A chemical in the photoreceptors that changes its form in response to light, producing an electrical change that signals to the nervous system that light is present.

photopigment

photopupillary reflex

reflex constriction of pupils when they are exposed to bright light

accommodation pupillary reflex

reflex constriction of the pupils when viewing close objects

contains visual receptors called rods and cones

retina

the light-sensitive pigment of the cells in the retina; it contains vitamin A.

rhodopsin

The "white" of the eye.

sclera

white part of outer (fibrous) tunic

sclera

visual acuity

sharpness or clearness of vision in one or both eyes

connects lens to the ciliary body

suspensory ligament

Closely associated with the lashes are oil-secreting glands called ____ that help to lubricate the eyes.

tarsal glands

oil glands along the edges of the eyelids that lubricate the eye

tarsal glands

Gel-like substance that helps to reinforce the eyeball.

vitreous humor

fills posterior cavity of eye

vitreous humor