C15 1-2

Question 1

Accessory structures of the eye?

Answer 1

Eyebrows, eyelids, conjunctiva, lacrimal apparatus

Question 2

Eyebrows?

Answer 2

shade eyes, keep sweat out

Question 3

Eyelids?

Answer 3

(Palpebrae) + eyelashes and associated glands. Protection and to keep eyes from drying out.

Tarsal glands - modified sebaceous glands contained in eyelid - secrete oily substance to keep eyelids lubricated. Chalazion = infection of tarsal gland.

Question 4

Conjunctiva?

Answer 4

Transparent mucous membrane that lines the whites of the eyes and eyelids.

Produces a mucus to moisten the eye.

Conjunctivitis

Question 5

Lacrimal apparatus?

Answer 5

Cleanses and protects the eye as it moistens it.

Consists of lacrimal gland and the ducts that drain lacrimal secretions into the nasal cavity.

Tears are dilute saline (cleanse/protect) that contains lysozyme which breaks down bacterial cell walls.

Lacrimal gland –>tears across surface of eye –> Tears drain: from medial commisure –> l. canaliculi –> into l. puncta –> l. sac –> nasolacrimal duct –> nasal cavity.

Question 6

Muscles?

Answer 6

Lateral/medial/superior/inferior rectus, inferior/superior oblique

Question 7

lateral rectus

Answer 7

moves eye laterally

Question 8

medial rectus

Answer 8

moves eye medially

Question 9

superior rectus

Answer 9

elevates eye and turns it medially

Question 10

inferior rectus

Answer 10

depresses eye and turns it medially

Question 11

inferior oblique

Answer 11

elevates eye and turns it laterally

Question 12

superior oblique

Answer 12

depresses eye and turns it laterally

Question 13

Layers of the eye?

Answer 13

Fibrous, Vascular, Inner

Question 14

What structures are included in the Fibrous layer?

Answer 14

Sclera, Cornea.

Question 15

What structures are included in the Vascular layer?

Answer 15

Choroid, Ciliary body, Iris

Question 16

What structures are included in the Inner layer? (Aka internal tunic, neural tunic)

Answer 16

Retina (Outer pigmented layer and Inner neural layer)

Question 17

Sclera function?

Answer 17

Function: protection, gives eye shape, and attachment for extrinsic eye muscle. Continuous with dura mater surrounding optic nerve.

Structure: Dense Irr CT, collagen/elastin, avascular

Question 18

Cornea?

Answer 18

Function: Let light in, Refraction, 70%.

Structure: Transparent, convex, anterior 1/6 of fibrous layer. 3 layers: inner - simp squam, mid - collagen, outer - strat squam. Cont. nerve endings. Avascular.

Gets nutrients from lacrimal glands and aqueous humor.

Question 19

Choroid?

Answer 19

Function: Blood supply , nourishment. Absorb extraneous light (allowing retina to absorb the remaining)

Structure: Posterior 5/6 of vascular layer, blood vessels, melanocytes/melanin

Question 20

Ciliary Body?

Answer 20

Function: control lens shape/anchor lens, secrete aqueous humor

Structure: ciliary muscles (smooth muscle) that encircles the lens, ciliary processes, ciliary zonule (suspensory ligaments)

Question 21

Iris?

Answer 21

Function: Control size of pupil, amount of light let in. Center is pupil.

Structure: 2 groups of smooth muscle, 2 layers of pigment forming cells, , vascular, nervous structures.

(oculomotor consticts pupil, sympathetic dilates)

Question 22

Ora serrata?

Answer 22

jagged margin between retina and ciliary body

Question 23

Retina - pigmented layer?

Answer 23

Function: absorb light - prevent it from scattering, MAIN, store vitamin A

Structure: Outer pigmented layer of retina. One cell thick, abuts choroid, covers ciliary body and posterior face of iris.

Question 24

Retina - neural layer?

Answer 24

Function: transduce light energy

Structure: inner layer, composed of neurons - photoreceptors (rods and cones) , bipolar cells, ganglion cells.

Question 25

Optic disc?

Answer 25

Where the optic nerve exits the eye. Not reinforced by sclera, weak spot.

Question 26

Fundus?

Answer 26

Posterior wall of retina

Question 27

Blind spot?

Answer 27

optic disc - lacks photoreceptors

Question 28

Rods? **know**

Answer 28

``` 100 mil per retina, rhodopsin (photosensitive pigment), vision in shades of gray, high sensitivity, low acuity, night (scotopic) vision, much convergence in retinal pathways, more numerous in periphery ```

Question 29

Cones? **know**

Answer 29

``` 3-10 mil per retina, photopsin (photosensitive pigment), color vision, low sensitivity, high acuity, day (photopic) vision, little convergence in retinal pathways, concentrated in fovea ```

Question 30

macula lutea

Answer 30

Oval region, lateral to blind spot, precisely at the eye's posterior pole. "yellow spot" 90% cones focus light rays here for best visual acuity 2mm

Question 31

fovea centralis

Answer 31

Pit in the center of macula lutea. 100% cones , best/sharpest vision

Question 32

wall of retina, what is special?

Answer 32

only place in the body where small blood vessels are visible in a living person.

Question 33

Aqueous humor

Answer 33

Made by ciliary processes, Brings nutrients and O2 to cornea and lens, removes wastes drains out of scleral venous sinus returns to blood supply

Question 34

Why are cornea transplants successful?

Answer 34

cornea is avascular - no rejection, immune system can't reach it.

Question 35

Posterior segment?

Answer 35

posterior to lens, cont. vitreous humor

Question 36

Vitreous humor?

Answer 36

Transmits light, supports post. surface of lens, holds retina against pigmented layer, contributes to intraocular pressure. Contains collagen fibers - clumping = floaters.

Question 37

Anterior segment?

Answer 37

Divided into two chambers: anterior/posterior. Anterior is between iris and cornea, posterior is between lens and iris. Filled with aqeous humor.

Question 38

lens?

Answer 38

Function: 30% of refraction. Changes shape to allow precise focusing of light on the retina Structure: Is avascular, biconcave, transparent, flexible - bounded by a dense fibrous elastic capsule. 1000 layers of cells without organelles - filled with crystallins (protein)