Histo - Eye

Question 1

Explain the Anatomy of the Eye

Answer 1

Question 2

What is this?

Answer 2

Eye

Question 3

What is this?

Answer 3

Eye with Optic Nerve

Question 4

What are the 3 chambers of the eye?

Answer 4

1. Anterior
   
   • btw corneal epithelium + anterior surface of iris
   • contains AQUEOUS HUMOR
     
     • pupillary part of lens
     • base of ciliary body
2. Posterior
   
   • posterior surface of iris + lens
   • contains AQUEOUS HUMOR
     
     • lens
     • zonular fibers
     • ciliary processes
3. Vitreous
   
   • Posterior to lens –> retina (lines it)
   • contains VITREOUS HUMOR

Question 5

What are the 3 tunics of the eye?

Answer 5

1. Outer tunic
   
   • sclera (opaque)
   • cornea (transparent)
     
     • limbus = jxn (canal of schlem & trabecular meshwork)
2. Middle tunic (Uvea)
   
   • vascular layer
   • ciliary body + choroid & iris
3. Inner tunic
   
   • retina & pigment epithelium

Question 6

What are the 4 things in this image?

Answer 6

Question 7

What are the 5 layers of the cornea?

Answer 7

1. Corneal epithelium
   
   • SSNK
2. Bowman’s layer (membrane)
   
   • ​modified basement membrane (collagen 1 & 5)
3. Corneal stroma
   
   • dense regular CT
   • keratocytes
   • ECM
     
     • Collagen 1, 5, 6
     • Proteoglycans
4. Decemet’s membrane
   
   • ​Collagen 8
5. Corneal endotheloum
   
   • ​not related to vascular endothelium

Question 8

What are the 4 key facts about the cornea?

Answer 8

1. Transparent
   
   • 2/3 of light refraction!
2. Avascular
   
   • NO BLOOD or lymphatic
3. Immune privileged
   
   • can be transplanted w/ little risk
     
     • keratoplasty
   • little MHC expression
4. Kept moist w/ tears
   
   • dry eye

Question 9

What are components of the Anterior Surface of the Cornea?

Answer 9

1. Corneal epithelium
2. Bowman’s membrane
3. Stroma

Curvature affects vision

• can reshape the STROMA w/ a laser!

Question 10

What are the components of the Posterior Surface of the Cornea?

Answer 10

1. Decemet’s membrane
   
   1. Type 8 collagen
   2. hexagonal meshwork
2. Corneal endothelium
   
   1. responsible for corneal DEHYDRATION
      
      1. ​Na+/K - ATPase

***MUTATIONS in Collagen 8 = FUCH’s Dystrophy***

• corneal stromal dystrophy
  
  • ​thickened Decemet’s
  • Guttae (outpocketing)
    
    • ​both cause corneal edema

Question 11

What produces aqueous humor?

Answer 11

Aqueous humor = secreted by ciliary processes

• Secreted into posterior chamber
• moves thru pupil –> anterior chamber
• Excess aqueous humor –>
  
  • resorbed by the SCLERAL VENOUS SINUS
  • aka CANAL of SCHLEM

Question 12

What is this?

Answer 12

Corneal-Scleral Junction

(and Canal of Schlem w/ Trabecular Meshwork)

• Glaucoma = rise in intraocular pressure
  
  • caused by blockage of aqueous humor!
  • (normal intraocular pressure = ~23mmHg)

Question 13

What are the 2 Regions of the Ciliary Body?

Answer 13

1. Uveal portion
   
   • continuous of choroid
   • ciliary muscle attached to lens by ZONULES of ZINN
   • fenestrated capillaries supplying blood to ciliary muscles
2. Neuroepithelial portion
   
   • outer pigmented epithelial layer
   • inner non-pigmented epithelial layer
     
     • continuous w/ RETINA
     • secretes AQUEOUS HUMOR

Question 14

What is this?

Answer 14

Question 15

What is this?

Answer 15

Question 16

What is this?

Answer 16

Ciliary Body

• SM
• Pigment!

Question 17

What is this? What are the 4 important parts?

Answer 17

Lens (Middle of Eye) - Epithelium!

1. Accomodation
   
   • ciliary muscles
2. Lens capsule
   
   • basement membrane
3. Lens epithelium
   
   • simple cuboidal epithelium or anterior
4. Lens fibers
   
   • elongated lens epithelium remnants
   • lose nuclei & organelles
   • fill w/ CRYSTALLINGS & FILENSIN
     
     • transparency & conformation of lens

Question 18

What is this?

Answer 18

Lens Fibers

• Fibers cells
  
  • ​filled w/ FILENSIN & CRYSTALLINS

Question 19

What is this?

Answer 19

Lens & Iris

1. Iris = forms pupil
   
   • contains 2 muscles:
     
     1. Sphincter pupillae
     2. Dilator pupillae

• Abundant melanocytes!

Question 20

What is Accomodation?

Answer 20

Accomodation

• Cilliary muscles allow focus:
  
  • FLAT = see FAR
    
    • relaxed
  • ROUND = see CLOSE
    
    • tense

Question 21

What is shown in this image?

Answer 21

1. Optic disc
   
   • whe​re ganglion layer axons LEAVE the eye as optic nerve
2. Fovea
   
   • Thinning due to fewer bodies & axons
   • NO RODS
   • INCREASED cones
   • Greatest visual acuity
3. Macula Lutea
   
   • Axon of CONE cells
   • Yellowish region AROUND fovea

Question 22

10 Layers of the Retina

Answer 22

[CHOROID]

1. Pigment epithelium
   •
   2. Layer of rods and cones

(Processing of light starts here)
•
3. Outer limiting layer
•
4. Outer nuclear layer

(nuclei of RODS & CONES)
•
5. Outer plexiform layer
•
6. Inner nuclear layer
•
7. Inner plexiform layer
•
8. Ganglion cell layer

(Closest to LIGHT)
•
9. Nerve fiber layer

(Leave retina via OPTIC NERVE)
•
10. Inner limiting layer

[VITREOUS

Question 23

What are the 10 layers?

Answer 23

Question 24

What is this?

Answer 24

Pigment Epithelium of Retina vs. Choroid

• Pigment epithelium = THIN
• Choroid = THICK & BLACK

Question 25

What is this?

Answer 25

Lacrimal Gland

• Produce tear film
  
  • continuous secretion
  • small, lightly stained granules
  • O2, metabolities, proteins,
  • lysozymes!

Question 26

What is this?

Answer 26

Eyelid

• Covered by CONJUCTIVA & SKIN
• Hair follicles
  
  • eyelashes
• Skeletal muscle
  
  • ORBICULARIS OCULI
  • innv = facial n.
• Tarsal Glands
  
  • secrete sebum
  • adds to tear film