Ch. 17, The Eye

Front 1

Three types of cones are:

Back 1

sensitive to red, blue and green

All colors due to differential stimulation of these 3 cones

Front 2

The shape of the lens (accomodation):

Back 2

far vision- flatter

close vision- more spherical

Front 3

Dark adaptation:

Back 3

increased sensitivity to light as we go into a low-light situation

in dim light we use only rods for vision

Front 4

Light adaptation:

Back 4

decreased sensitivity as we go into bright-light situations

in bright light we use only cones for vision

Front 5

The sympathetic division innervates:

Back 5

the radial M, which dilates the pupil

Front 6

The Parasympathetic division (N. 3) innervates:

Back 6

the circular Ms, which constrict pupil

Front 7

The lens;

Back 7

reverses images on the retina

Front 8

Tears:

Back 8

keep cornea moist

wash away dirt

help prevent infection (they contain lyzosome, an antibacterial protein)

Front 9

Aqueous humor:

Back 9

fills the anterior cavity

It is produced by the ciliary body and exits the anterior chamber at the angle between the cornea and the iris.

Front 10

Vitrious humor:

Back 10

fills the posterior cavity

keeps the retina pressed against the choroid

is permanent, not replenished

Front 11

Pupils:

Back 11

dilate in dim light

constrict in bright light

Front 12

Direct reflex of pupil:

Back 12

if light is shined in one eye, its pupil constricts

Front 13

Consensual reflex of pupil:

Back 13

both pupils constrict (react) if light is shined into one

Front 14

Rods:

Back 14

for dim light vision

give B&W and grey only

vastly more of them than cones

Front 15

Cones:

Back 15

for bright light vision

high acuity and color vision

less than amount than rods

Front 16

Palpebral fissure:

Back 16

area of the globe exposed between the upper and lower eye lids.

Front 17

eyelids:

Back 17

keep light out

during blinking, spread tear film over cornea

Front 18

Vision is absent at:

Back 18

the optic disc (the optic nerve head, where the optic nerve attaches to the globe)

Front 19

Ciliary body contains:

Back 19

the ciliary muscle

secretes aqueous humor

supports the lens and iris

Front 20

Binocular vision allows:

Back 20

a wide field of view

increased sensitivity to light

depth perception

Front 21

Visual acuity is greatest at the:

Back 21

fovea
(a depression in the macula, which is at the visual axis of the eye)

only cones present at fovea

foveal vision used for reading, observing

50% of the visual cortex receives foveal images

Front 22

Iris:

Back 22

pigmented structure in anterior cavity

forms the pupil

contains two muscles that can either dilate the pupil (radial M) or constrict the pupil (the sphincter)

Front 23

Choroid:

Back 23

Middle layer of the eye's wall

vascular and pigmented

Front 24

Retina:

Back 24

innermost layer of eye's wall

contains:

photoreceptor cells (rods and cones)

bipolar and ganglion cells

Front 25

Sclera:

Back 25

white of the eye

outermost layer of eye wall

protects and supports the inner structure

continuous with cornea (the transparent tissue that allows light to enter the eye)

Front 26

Conjunctiva

Back 26

non-keratinizing stratified squamous epithelium-lined membrane

lines the inner surfaces of the lids

continues onto the globe, covering the sclera (not the cornea) in the palpebral fissure

seals off the globe in the bony orbit from the outside

Front 27

Wavelengths

Back 27

color of something is due to wavelength of light reflected (not absorbed)

an object that reflects all wavelengths is white

an object that absorbs all wavelengths is black

Front 28

Refraction

Back 28

light rays bend as they go from one medium to another

Front 29

accomodation

Back 29

change in shape of lens that permits near vision

Front 30

convergance

Back 30

both eyes rotate medially to look at close objects

Front 31

Conjugate gaze

Back 31

both eyes look at the same object

Front 32

cornea and lens

Back 32

both refract light

75% of refraction by cornea

25% of refraction by lens

Front 33

Extrinsic and intrinsic muscles

Back 33

Extrinsic Ms= EOMs

Intrinsic Ms= the pupil constrictor, pupil dilator and ciliary M.

Front 34

Tears

Back 34

flow from lacrimal gland medially to the drainage apparatus and then to the nasal cavity

Front 35

Eye's adnexal (accessory) structures include:

Back 35

EOMs
eye-lids
lacrimal glands
tear drainage apparatus