COM 1 Cytology week 4 Flashcards
1
Q
What is each eye cushioned with
A
- Adipose tissue
2
Q
What helps to focus the light in eyes
A
- Transparent tissues
3
Q
Name the 3 main eye layers
A
- External fibrous layer
-Middle vascular layer
-Inner sensory layer
4
Q
What does the external fibrous layer include
A
- Includes sclera and cornea
5
Q
What does the middle vascular layer contain
A
- Choroid, ciliary body and iris
6
Q
What is the inner sensory layer + function
A
- The retina, which connects to the the brain via the optic nerve
7
Q
Explain the structure of lens
A
- Transparent, biconvex structure, held by zonular fibers
8
Q
Explain the structure of the iris + function
A
- The pigmented part that surrounds the pupil
- Controls light entry
9
Q
What is the aqueous humor
A
- Fluid in anterior and posterior chambers
10
Q
What is the vitreous Body
A
- Gel like substance in the posterior vitreous chamber
11
Q
Where is the vitreous body located
A
- Behind the lens
12
Q
What week does the eye start to develop
A
4
13
Q
Explain the development of the optic vesicles- What they form from, and what they develop into
A
- Form the forebrain and develop in optic cups and stalks
14
Q
During the 4 week what does the surface ectoderm form
A
- Lens vesicle after intercting with the optic cups
15
Q
What does the optic stalk become during the 4th week of development
-What supports the development of this
A
- The optic nerve
-hyaloid vessels
16
Q
What does the mesenchyme form during the 4 th week
A
Outer layers and vitreous body
17
Q
What does the retina develop from
A
- Optic cup and corneal epithelium from the surface ectoderm
18
Q
What is the outermost layer of the eye
A
- External Fibrous layer
19
Q
What portion does the sclera make up of the external fibrous layer
A
Posterior 5/6
20
Q
What portion does the cornea make up of the external fibrous layer
A
- Anterior 1/6
21
Q
Where do the sclera and cornea joint at
A
- Border called limbus
22
Q
Explain the structure of the sclera
A
-White opaque part of the eye
23
Q
What does the sclera provide/function
A
- Provides protection for inner structrues
-Attchemnet sites for extraocular muscles
24
Q
What is sclera made out of
A
Dense connective tissue with type 1 collagen
25
What is present near the outer surfce of the sclera
- Micorvasculature
26
What muscles insert into the sclera anteriolry
- Extraocular muscles
27
Posteriorly,:
-Does the sclera thicken
-Where does the sclera join
-What does it contain
- Yes
-The optic nerve epineurium
-Contains the suprachoroid lamina
28
Explain the structure of the cornea
- Transparent , avascular and covers the front of the eye
29
How many layers does the cornea have
5
30
Name all the 5 layers the cornea has
-Corneal Epithelium
-Bowmans Membrane
-Stroma
-Descemet membrane
-Corneal Endothelium
31
Explain the structure of the corneal epithelium
- Stratified squamos, nonkeratinized
32
What is the corneal epithelium rich in
- Sensiry nerves
33
Why does the surface of the corneal epithelium habe microvili
For tear film stability
34
Where is bowsman membrane located
Under the epithelium
35
What does the bowsman membrane provide
- Strength and infection protection
36
What is the stroma composed of
- Orthogonally arranged collagen fibers + contains keratocytes
37
What are keratocytes
- Modified fibroblasts
38
What is the descemets Membrane
Basement membrane of the endothelium
39
What tyoe if cells does corneal Endothelium contain
Simple squamous cells
40
What does corneal endothelium use and whaty does it regulate
Uses Na+/K+ ATPase pumps to regulate hydration of the stroma for transparency and light refraction
41
What is Limbus
Transitional zone between the transparent cornea and opaque sclera
42
Where does bowman membrane end
- At the limbus
43
What do the stem cells in the limbus generate
- Progenitor cells
44
What is the descemet membrane and endothelium replaced by
- Trabecular meshwork, a system of channels for fluid drainage
45
What does trabecular meshwrok lead to
- Scleral venous sinus
46
What is the function of scleral venous sinus
- Drains aqueous humor into scleral veins
47
What is another name for the vascular layer of the eye
Uvea
48
How much of the eye does the choroid in the vascular layer make up
Posterior 2/3 of the eye
49
What is the choroid rich in
Blood vessels
50
What does choroid contain + what do they form
Melanocytes , which form a black layer to prevent light scattering
51
Name the 2 main layers that the choroid contains
Choriocapillary laminate
Brush membrane
52
Explains the function of the choriocapillary laminate in the choroid
Nourishes the retina
53
What’s does the bruch membrane ( in the choroid) contain and function
Collagen and elastic fibers
Supports the pigmented retina
54
What is the cillary body + funci
an Anterior extension of the choroid , which surrounds the lens
55
Name the 4 key components of the cillary body
- Ciliary muscle
- Ciliary processes
- Aqueous humour pathway
- Ciliary Zonule
56
What does the cillary muscle contain + the function of the contents
3 smooth muscle groups
- For lens shape change
57
Name the 2 layers the cillary processes in the cillary body contains
-Pigmented layer
-Non-pigmented layer
58
Describe the structure of the pigmented layer in the cillary processes
- Dark, continous with pigmented retina
59
What does the non pigemnted layer in the cillary processes secrete
- Aqueous humor
60
Explain the aqueous humor pathway
- From the posterior chamber to the Pupil, to the ANterior chamber then to the drainage angle
61
What is the function of the cillary zonule
Holds the lens in place
62
What is the most anterior part of the uvea( Middle vascular layer)
- Iris
63
What is the function of the iris
Covers the lens
64
What does the anterior surface of the iris contain
-Fibroblasts and melanocytes, NO EPITHELIUM
65
In the iris, what does the stroma consist of
- Loose connective tissue with melanocytes and sparse blood vessles
66
What does the posterior surface of the Iris contain
2 layered pigmented epithelium:
- Dilator pupillae muscle
-Sphincter pupillae muscle
67
What is eye colour determined by
Melanocyte number and melanin content
68
Less pigment means what eye colour
- Blue eyes
69
More pigment means what eye colour
- Green/brown
70
Almost no pigment means what eye colour
Pink in albinism
71
What is the Vitreous Body made out of
99% water, collagen fibrils and hyaluronate
72
What does the vitreous body fill
- Fills the vitreous chamber behind the lens
73
What is the vitreous body surrounded by
Vitreous membrane
74
What cells are present in Vitreous body
Hyalocytes
Macrophages
75
What does hyalocytes in the vitreous body produce
- Hyaluronate and collagen
76
What is the function of the vitreous body
Maintains eye shape and light transmission
76
- What is the function of lens
Focuses light onto the retina
76
What does the lens develop from
Surface ectoderm
77
Name the 3 components in Lens
- Lens capsule
-Subscapular lens epithelium
-Lens fibers
78
What is the lens capsule in the lens made out of
Type 4 COLLAGEN and proteoglycans
79
What is the function of the lens capsule in the lens
Provides attachment for ciliary zonule fibers
80
What does the Subscapular lens Epithelium contain
- Single layer of cuboidal cells
81
What is the lens fiber in the lens filled with
- crystallin proteins for refraction and transparency
82
In distant vision explain what happens to the cillary muscles and lens
- Cillary muscles relax
-Lens flatten
83
In near vision explain what happens to the cillary muscles and lens
- Cillary muscles contract and lens become rounder
