Anatomy and physiology Flashcards
1
Q
What are the components of the adnexa?
A
- Eyelids
- Conjunctiva
- Nasolacrimal system
- Orbit
2
Q
What are the 3 tunics of the globe and what are the components?
A
- Fibrous: cornea and sclera
- Vascular uvea: Iris, ciliary body, choroid
- Nervous: retina
3
Q
What are the 2 component of the ocular media?
A
- Aqueous humor
- Vitreous humor
4
Q
What makes up the eyelid?
A
- Outermost haired skin
- Inner surface conjunctiva
- Stroma containing muscle
- Medial and lateral canthus
5
Q
What makes up the eye margin?
A
- Cilia: eyelashes
- Tarsal gland: Meibomian
6
Q
What muscles are important for eyelid movement?
A
- Orbicularis oculi (circumferential striations): innervated by CN VII = CLOSE
- Levator palpebrae superioris (vertical striations): innervated by CN III = OPEN
7
Q
What is the function of the eyelids?
A
- Protect
- Lubricate: distribute tears
- Tarsal glands produce oil lipid layer of the tear film
8
Q
What are the pathophysiology related to eyelid diseases?
A
- Corneal irritation
- Tear-film quality disorders
9
Q
What are the components of the third eyelid?
A
- T-shaped cartilage
- Lined by conjunctiva
- Lymphoid follicles on bulbar surface
- Tear-producing gland at the base of cartilage
10
Q
What is the function of the third eyelid?
A
- Protection
- Gland of third eyelid produces aqueous tears
11
Q
What are the pathophysiology related to third eyelid issues?
A
- Corneal irritation
- Tear film quantity disorders
12
Q
What are the 2 types of conjunctiva and what do the connect to?
A
- Bulbar conjunctiva: lines the globe and extends from the limbus to the fornix
- Palpebral conjunctiva: lines the inner eyelid and extends from the fornix to the lid margin
13
Q
What is the function of the conjunctiva?
A
- Goblet cells produce mucin layer of tears
- Lymphoid follicles act as immune surveillance
14
Q
What is the pathophysiology of conjunctival disease?
A
- Reaction to antigens: lymphoid hyperplasia
- Inflammation
- Tear film quality disorders
15
Q
What are the 3 tear film layers? What produces them? What is there function?
A
- Innermost mucin: produced by the goblet cells of the conjunctiva
o Act as stability of tear film; hydrophilic surface for tears to spread evenly - Middle aqueous: produced by the aqueous humor
o Acts to supply oxygen and nutrients to the cornea - Outer oily: produced by tarsal glands of the eyelids
o Act to reduce and prevent evaporation
16
Q
What are the functions of tears?
A
- Provide optically uniform corneal surface
- Remove foreign material and debris
- Permit passage of oxygen and nutrients to the cornea
- Antimicrobial function
17
Q
What is the result of alteration of quantity and quality of tears?
A
- Chronic dry eye
- Corneal edema
- Vascularization
- Keratinization
18
Q
What are the component of the nasolacrimal system?
A
- Upper and lower puncta
- Canaliculi
- Lacrimal sac
- Nasolacrimal duct
19
Q
What is the function of the nasolacrimal system?
A
- Tear drainage
20
Q
What happens if the NL system is not working?
A
- Epiphora
21
Q
What are the components of the orbit?
A
- Orbital bones
- Periorbital: connective tissue around the orbit and orbital floor (soft tissue)
- Fat
- Extraocular muscles
- Lacrimal gland
- Vessels and nerves: orbital foramina
22
Q
What is the purpose of the open verses closed orbit?
A
- Carnivores = open: extension of the jaw
- Herbivores = closed: protection
23
Q
What are the extraocular muscles and function?
A
- Dorsal, ventral, medial and lateral rectus: movement of the eye
- Dorsal and ventral oblique: twist/rotate the eye
- Retractor bulbi: sucks the eye into the orbit
24
Q
What are the nerves that innervate the EO muscles?
A
- DVM rectus + V oblique: CNIII
- D oblique: CN IV
- L rectus, retractor bulbi: CN V
25
What are some periorbital structures?
- Oral and nasal cavity
- Tooth roots
- Paranasal sinuses
26
What are the functions of the orbit?
- Protect and cushion the globe
- Conduit for vessels and nerves
- Attachment for muscles to move the eye
27
What would happen if a tumor or an abscess grew in the orbit?
- Exophthalmos: push the globe out of the eye
- Decreased movement: muscle impingement
- Dry cornea
28
What are the pathophysiology of orbital disease?
```
- Change in volume
o Exophthalmos: increase
o Enophthalmos: decrease
- Impaired function of orbit structures
o Motility, strabismus, anisocoria, blindness, episcleral congestion, tear production
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29
What makes up the fibrous tunic of the globe
- Cornea: clear
- Sclera: not clear
- Limbus: line of pigment at the junction between cornea and sclera
30
What is the cornea made up of?
- Outer epithelium
- Stroma: collagen
- Descemet’s membrane: basement membrane
- Endothelium: 1 cell layer thick
31
What is the function of the cornea?
- Refracts light: corneal curvature
| - Protection
32
how is the cornea clear for vision?
- No pigment and non-keratinized
- Organized collagen lamellae
- Low water content
- Avascular
33
How is the low water content maintained in the cornea?
- Active pumping in endothelium via a NA/K ATPase
| - Physical barrier: tight junctions in the endothelium and epithelium
34
Where does the cornea get nutrition and oxygen from?
- Aqueous humor and tears
35
What changes do you expect in the cornea related to disease?
- Corneal edema
36
How does the cornea loss clarity?
- Edema
- Cellular, lipid or mineral infiltration
- Scarring
- Pigmentation
- Keratinization
37
What is corneal ulceration? How do you diagnose this?
- Loss of the superficial layer of the epithelium
| - Dx: fluorescein stain
38
What are the different layers to the sclera?
- Episclera: loose connective tissue below the conjunctiva
| - Sclera proper: dense connective tissue
39
What are the functions of the sclera?
- Protection of intraocular structures
| - Attachment for extraocular muscle
40
What is the pathophysiology of scleral disease?
- Inflammation
- Motility disorders
- Strabismus
41
What are the components of the vascular tunic?
- Anterior uvea: iris and ciliary body
| - Posterior uvea: choroid and tapetum
42
What are the muscles associated with the iris?
- Sphincter muscle (near the pupil): innervated by CN III
| - Dilator muscle (posterior stroma): sympathetic innervation
43
What is the function of the iris?
- Pupil: opening for light entering the eye
44
What are the components of the ciliary body?
- Bilayer epithelium: pigmented and non-pigmented
- Stroma: vascular and smooth muscle
- Pars plicata: ciliary processes which suspends the lens via the zonules
- Pars plana: smooth transition to the retina
45
What is the function of the bilayer epithelium of the ciliary body?
- Production of aqueous humor
46
What is the function of the zonules?
- Suspend the lens
47
What is the function of the smooth muscle of the ciliary body?
- Accommodation of light: focus
48
What is the filtration angle?
- Located where the cornea and iris meet
- Pectinate ligaments span the opening
- Made up of a trabecular meshwork
49
What is the function of the filtration angle?
- Drainage of aqueous humor
50
What are the components of the choroid?
- Stroma: highly vascular and contains the tapetum dorsally
| - Choriocapillaries: on the surface of the choroid that act as feeders into the tapetum
51
What is the function of the choroid?
- Nutrition to outer retina
| - Tapetum: increases light capture
52
What are the components of the blood aqueous barrier?
- Tight junctions between the nonpigmentary ciliary epithelial cells and between iris capillary endothelial cells
53
What is the function of the BAB?
- Prevents low molecular weight substances from entering aqueous humor: protein and cells
54
What is some pathophysiology of the BAB?
- Uveitis (inflammation of the uvea) causes a breakdown in the BAB and leads to corneal edema
55
What are the main components of the retina?
- Retinal pigment epithelium: one cell thick
| - Neurosensory retina: multiple layers
56
What are the functions of the retinal pigment epithelium?
- Transport of ions and metabolites
| - Photoreceptor renewal
57
What is the pathophysiology of retinal disease?
- Retinal degeneration
58
What are the function of the photoreceptors?
- Rods = night vision
| - Cones = day vision, colour, high resolution
59
How does phototransduction occur?
- Light is changed into an electrical signal
| - Transmitted through retinal layers to optic nerve
60
What is the relationship between neurosensory retina and the RPE?
- Layers are apposed but there is no firm attachment
| - Thus the RPE and neurosensory retina detach easily
61
What are the pathophysiology of retinal and optic nerve disease?
- Detachment
- Tears/holes
- Inflammation
- Degeneration
62
What are the 2 components of ocular media?
- Aqueous humor
| - Vitreous humor
63
Describe the aqueous humor?
- Clear, watery and found in the anterior chamber
64
Describe the vitreous humor?
- Clear, gel-like and found in the posterior chamber
65
What is the composition of the vitreous humor?
- 98% water, 2% collagen and hyaluronic acid
| - Collagen fibrils provide a frame work
66
What is the function of the vitreous humor?
- Transmits light
- Maintains shape of eye
- Maintains normal position of retina
67
What is the pathophysiology of vitreous humor?
- Degeneration: condensation of collagen fibrils leads to loss of framework and liquefaction
- Opacities
68
What is the consequence of retina with disease of the vitreous humor?
- Retinal detachment
69
What is the function of aqueous humor?
- Maintains the intraocular pressure
| - Nutrition and waste removal
70
What is involved in aqueous circulation?
- Posterior chamber, pupil, anterior chamber, filtration angle and collecting veins
71
What happens to the aqueous humor when the BAB is broken?
- Protein and cellular leakage into the aqueous humor
o Leads to cloudy aqueous = aqueous flare and Hypopyon
- Disruption of normal nutrition and waste removal
o Cornea – edema
o Lens - cataract
72
What happens to eye if aqueous humor outflow is reduced?
- Increase intra-ocular pressure
73
What are the components to the lens?
- Suspended by zonules from ciliary processes
| - Capsule surrounds lens cells: fibers
74
What are the function of the lens?
```
- Clarity
o Avascular
o Dehydrated state
o Solubility of lens proteins
- Refraction of light: focus onto the retina
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75
What is the pathophysiology of lenticular disease?
- Cataracts
o Due to proteins and or hydration changes: opacity
- Lens luxation
o Due to zonular breakdown
