Lecture 16 - The Eye Flashcards
What are the different tunics of the eye and what structure do they compose?
(Slide 9-10)
Fibrous tunic:
- sclera (tunica fibrosa)
- cornea
Vascular tunic:
- choroid
- ciliary body
- iris
Inner tunic:
-retina
What are the different layers off the sclera and what are their characteristics?
(Slide 12)
Episcleral layer:
- outer layer
- loose collagen and elastic fibers
- highly vascular
- attaches conjunctiva to sclera
Sclera proper:
- collagen fibers parallel to surface of sclera
- attachment of tendons for eye muscles
Lamina cribrosa:
-perforated disc for optic nerve fibers
Anteriorly, the sclera is continuous with __________ and this junction is called __________. Posteriorly, the sclera continuous with __________.
(Slide 13)
Cornea; limbus; dura of optic nerve
What are the different layers of the cornea and what are their characteristics?
(Slide 14)
Corneal epithelium:
- stratified, nonkeratinized epithelium
- highly mitosis
Bowman’s membrane:
- acellular layer between epithelium and stroma
- randomly arranged collagen
Corneal stroma:
-thin, ordered arrays of collagen
Descemet’s membrane:
- acellular layer of collagen bundles
- separates stroma from endothelium
Corneal endothelium:
-simple squamous
What are the characteristic of the choroid?
Slide 17
-extends anteriorly from the ora serrata of retina
-highly vascularized with loose connective tissue
—supplies nutrients to retina
—contains melanocytes
-Bruch’s membrane
—acellular fused basal lamina
What are the characteristics of the ciliary body?
L16 S20+26
-expansion of choroid peripheral to the lens
-produces aqueous humor
-suspensions ligaments
anchor the lens
-ciliary muscles change the shape of the lens
-nonpigmentd layer of cells producing aqueous humor
What is accommodation?
L16 S27
- changing of the thickness of the lens for close or distant vision
- achieved by contracting or relaxing the ciliary muscles
What are the characteristics of the iris?
L16 S28
- separates anterior and posterior chambers
- surrounds pupil
- double layer of epithelium; one pigmented, the other radially oriented myofilaments
- contains melanocytes
What are the characteristics of the retina?
L16 S29
Photosensitive region:
- posterior to ora serrata
- optic disc; where optic nerve exits
- foeva centralis; area of highest vision acuity; only contains cones
Non-photosensitive region:
- anterior to ora serrata
- double cell layer covering iris, ciliary body, and ciliary process
What are the different chambers of the eye and what differentiates them?
(L16 S31)
Anterior chamber:
-posterior to cornea; anterior to iris
Posterior chamber:
-posterior to iris; anterior to lens
Vitreal chamber:
- posterior to lens
- contains vitreous body
What are the layers of the retina from outer to inner?
L33 S36
- pigmented epithelium
- inner and out segment of rods and cones
- external limiting membrane
- outer nuclear layer
- outer plexiform layer
- inner nuclear layer
- inner plexiform layer
- ganglion cell layer
- optic nerve
- interval limiting membrane
What are the different types of neurons found in the retina and where are their cell bodies found?
(L16 S34-36)
Rods and cones:
- first order neurons
- located in outer nuclear layer
Bipolar cells:
- second order neurons
- located in inner nuclear layer
Ganglion cells:
- third order neurons
- ganglion cell layer
What cell types are present in the retina and what do they do?
(L16 S37-38)
Pigmented epithelial cells:
- synthesize melanin and photosensitive pigments
- form blood-retina barrier
Bipolar cells:
-conducting neurons which synapse with rods and cones
Horizontal cells:
-interconnect rods, cones, and bipolar cells
Amacrine cells:
-connected ganglion cells and bipolar neurons
Muller cells:
-neuroglial cells
Ganglion cells:
-axons form optic nerve
Differentiate between rods and cones.
L16 S49
Rods:
- use rhodopsin
- sensitive to low-intensity light
- black-and-white vision
- outer segments not continuous with plasmalemma
- many rods synapse with one bipolar cell
Cones:
- use 3 different iodopsins
- sensitive to high-intensity light
- responsible for color vision
- outer segment continuous with plasmalemma
- synapse with single bipolar cell
What is the general structure of a photoreceptor cell?
L16 S46-47
Spehrule (rod) or pedicle (cone)
Inner segment:
-mitochondria and other organelles
Cell body:
-nucleus and short axon
Outer segment:
-contains stacks of photoreceptor disks
