COM 1 Cytology week 4

Question 1

What is each eye cushioned with

Answer 1

• Adipose tissue

Question 2

What helps to focus the light in eyes

Answer 2

• Transparent tissues

Question 3

Name the 3 main eye layers

Answer 3

• External fibrous layer
  -Middle vascular layer
  -Inner sensory layer

Question 4

What does the external fibrous layer include

Answer 4

• Includes sclera and cornea

Question 5

What does the middle vascular layer contain

Answer 5

• Choroid, ciliary body and iris

Question 6

What is the inner sensory layer + function

Answer 6

• The retina, which connects to the the brain via the optic nerve

Question 7

Explain the structure of lens

Answer 7

• Transparent, biconvex structure, held by zonular fibers

Question 8

Explain the structure of the iris + function

Answer 8

• The pigmented part that surrounds the pupil
• Controls light entry

Question 9

What is the aqueous humor

Answer 9

• Fluid in anterior and posterior chambers

Question 10

What is the vitreous Body

Answer 10

• Gel like substance in the posterior vitreous chamber

Question 11

Where is the vitreous body located

Answer 11

• Behind the lens

Question 12

What week does the eye start to develop

Answer 12

4

Question 13

Explain the development of the optic vesicles- What they form from, and what they develop into

Answer 13

• Form the forebrain and develop in optic cups and stalks

Question 14

During the 4 week what does the surface ectoderm form

Answer 14

• Lens vesicle after intercting with the optic cups

Question 15

What does the optic stalk become during the 4th week of development
-What supports the development of this

Answer 15

• The optic nerve
  -hyaloid vessels

Question 16

What does the mesenchyme form during the 4 th week

Answer 16

Outer layers and vitreous body

Question 17

What does the retina develop from

Answer 17

• Optic cup and corneal epithelium from the surface ectoderm

Question 18

What is the outermost layer of the eye

Answer 18

• External Fibrous layer

Question 19

What portion does the sclera make up of the external fibrous layer

Answer 19

Posterior 5/6

Question 20

What portion does the cornea make up of the external fibrous layer

Answer 20

• Anterior 1/6

Question 21

Where do the sclera and cornea joint at

Answer 21

• Border called limbus

Question 22

Explain the structure of the sclera

Answer 22

-White opaque part of the eye

Question 23

What does the sclera provide/function

Answer 23

• Provides protection for inner structrues
  -Attchemnet sites for extraocular muscles

Question 24

What is sclera made out of

Answer 24

Dense connective tissue with type 1 collagen

Question 25

What is present near the outer surfce of the sclera

Answer 25

- Micorvasculature

Question 26

What muscles insert into the sclera anteriolry

Answer 26

- Extraocular muscles

Question 27

Posteriorly,: -Does the sclera thicken -Where does the sclera join -What does it contain

Answer 27

- Yes -The optic nerve epineurium -Contains the suprachoroid lamina

Question 28

Explain the structure of the cornea

Answer 28

- Transparent , avascular and covers the front of the eye

Question 29

How many layers does the cornea have

Answer 29

5

Question 30

Name all the 5 layers the cornea has

Answer 30

-Corneal Epithelium -Bowmans Membrane -Stroma -Descemet membrane -Corneal Endothelium

Question 31

Explain the structure of the corneal epithelium

Answer 31

- Stratified squamos, nonkeratinized

Question 32

What is the corneal epithelium rich in

Answer 32

- Sensiry nerves

Question 33

Why does the surface of the corneal epithelium habe microvili

Answer 33

For tear film stability

Question 34

Where is bowsman membrane located

Answer 34

Under the epithelium

Question 35

What does the bowsman membrane provide

Answer 35

- Strength and infection protection

Question 36

What is the stroma in the cornea composed of

Answer 36

- Orthogonally arranged collagen fibers + contains keratocytes

Question 37

What are keratocytes

Answer 37

- Modified fibroblasts

Question 38

What is the descemets Membrane

Answer 38

Basement membrane of the endothelium

Question 39

What tyoe if cells does corneal Endothelium contain

Answer 39

Simple squamous cells

Question 40

What does corneal endothelium use and whaty does it regulate

Answer 40

Uses Na+/K+ ATPase pumps to regulate hydration of the stroma for transparency and light refraction

Question 41

What is Limbus

Answer 41

Transitional zone between the transparent cornea and opaque sclera

Question 42

Where does bowman membrane end

Answer 42

- At the limbus

Question 43

What do the stem cells in the limbus generate

Answer 43

- Progenitor cells

Question 44

What is the descemet membrane and endothelium replaced by

Answer 44

- Trabecular meshwork, a system of channels for fluid drainage

Question 45

What does trabecular meshwrok lead to

Answer 45

- Scleral venous sinus

Question 46

What is the function of scleral venous sinus

Answer 46

- Drains aqueous humor into scleral veins

Question 47

What is another name for the vascular layer of the eye

Answer 47

Uvea

Question 48

How much of the eye does the choroid in the vascular layer make up

Answer 48

Posterior 2/3 of the eye

Question 49

What is the choroid rich in

Answer 49

Blood vessels

Question 50

What does choroid contain + what do they form

Answer 50

Melanocytes , which form a black layer to prevent light scattering

Question 51

Name the 2 main layers that the choroid contains

Answer 51

Choriocapillary laminate Brush membrane

Question 52

Explains the function of the choriocapillary laminate in the choroid

Answer 52

Nourishes the retina

Question 53

What’s does the bruch membrane ( in the choroid) contain and function

Answer 53

Collagen and elastic fibers Supports the pigmented retina

Question 54

What is the cillary body + funci

Answer 54

an Anterior extension of the choroid , which surrounds the lens

Question 55

Name the 4 key components of the cillary body

Answer 55

- Ciliary muscle - Ciliary processes - Aqueous humour pathway - Ciliary Zonule

Question 56

What does the cillary muscle contain + the function of the contents

Answer 56

3 smooth muscle groups - For lens shape change

Question 57

Name the 2 layers the cillary processes in the cillary body contains

Answer 57

-Pigmented layer -Non-pigmented layer

Question 58

Describe the structure of the pigmented layer in the cillary processes

Answer 58

- Dark, continous with pigmented retina

Question 59

What does the non pigemnted layer in the cillary processes secrete

Answer 59

- Aqueous humor

Question 60

Explain the aqueous humor pathway

Answer 60

- From the posterior chamber to the Pupil, to the ANterior chamber then to the drainage angle

Question 61

What is the function of the cillary zonule

Answer 61

Holds the lens in place

Question 62

What is the most anterior part of the uvea( Middle vascular layer)

Answer 62

- Iris

Question 63

What is the function of the iris

Answer 63

Covers the lens

Question 64

What does the anterior surface of the iris contain

Answer 64

-Fibroblasts and melanocytes, NO EPITHELIUM

Question 65

In the iris, what does the stroma consist of

Answer 65

- Loose connective tissue with melanocytes and sparse blood vessles

Question 66

What does the posterior surface of the Iris contain

Answer 66

2 layered pigmented epithelium: - Dilator pupillae muscle -Sphincter pupillae muscle

Question 67

What is eye colour determined by

Answer 67

Melanocyte number and melanin content

Question 68

Less pigment means what eye colour

Answer 68

- Blue eyes

Question 69

More pigment means what eye colour

Answer 69

- Green/brown

Question 70

Almost no pigment means what eye colour

Answer 70

Pink in albinism

Question 71

What is the Vitreous Body made out of

Answer 71

99% water, collagen fibrils and hyaluronate

Question 72

What does the vitreous body fill

Answer 72

- Fills the vitreous chamber behind the lens

Question 73

What is the vitreous body surrounded by

Answer 73

Vitreous membrane

Question 74

What cells are present in Vitreous body

Answer 74

Hyalocytes Macrophages

Question 75

What does hyalocytes in the vitreous body produce

Answer 75

- Hyaluronate and collagen

Question 76

What is the function of the vitreous body

Answer 76

Maintains eye shape and light transmission

Question 76

- What is the function of lens

Answer 76

Focuses light onto the retina

Question 76

What does the lens develop from

Answer 76

Surface ectoderm

Question 77

Name the 3 components in Lens

Answer 77

- Lens capsule -Subscapular lens epithelium -Lens fibers

Question 78

What is the lens capsule in the lens made out of

Answer 78

Type 4 COLLAGEN and proteoglycans

Question 79

What is the function of the lens capsule in the lens

Answer 79

Provides attachment for ciliary zonule fibers

Question 80

What does the Subscapular lens Epithelium contain

Answer 80

- Single layer of cuboidal cells

Question 81

What is the lens fiber in the lens filled with

Answer 81

- crystallin proteins for refraction and transparency

Question 82

In distant vision explain what happens to the cillary muscles and lens

Answer 82

- Cillary muscles relax -Lens flatten

Question 83

In near vision explain what happens to the cillary muscles and lens

Answer 83

- Cillary muscles contract and lens become rounder