Uveal Tract Flashcards
Iris: Location
Separates anterior and posterior chambers
Iris: Function
Varies aperture of pupil to control the amount of light focusing on the retina
Diameter: Iris
~13mm
Thickness: Iris
0.1mm at root
0.6mm at collarette
Diameter: Pupil
1-8mm (varies in different lighting)
Blood Supply: Iris
Major arterial circle in ciliary body - ends with capillary loops at pupil margin
Blood Drainage: Iris
Ciliary plexus
Nerve Supply: Iris
Long and short ciliary nerves from nasociliary branch of ophthalmic division of trigeminal nerve
Layers: Iris (3)
Anterior Border Layer
Stroma
Epithelium
Anterior Border Layer (iris) (3)
More melanocytes = velvety brown texture
Less pigment in Cryts of Fuch
Fibroblasts and meloncytes
Stroma (iris) (3)
Collagen connective tissue
Blood vessels
Iris sphincter muscle
Muscle type: Iris Sphincter Muscle
Smooth
Epithelium (iris) (3)
Pupil ruff
Dilator pupillae muscle
Densely packed melanin
Purpose of melanin in epithelium (iris)
Absorbes light
Choroid: Location
Sandwiched between outer sclera and inner retina from ora serrata to edge of optic nerve
Choroid: Function (4)
Allows for metabolic exchange
Waste removal to and from photoreceptors
Regulates temperature of globe
Deep pigment layer to absorbe light
Choroid: Blood Supply (2)
Major arterial circle
Circle of Haller-Zinn
Layers: Choroid (4)
Suprachoroid
Stroma
Choriocapillaris
Basal Lamina
Suprachoroid (4)
Outer layer
30um thick with structural link of collagen fibrils with sclera
Contains meloncytes and fibroblasts
Route for nerves and blood vessels
Stroma (choroid) (2)
Pigment layer
Highly vascular
Choriocapillaris (3)
Single layer of wide capillaries
Lies flat against base layer
Thickness and internal blood pressure to counter act intraocular pressure
Basal Lamina (4)
2-4um thick
Smooth layer for retinal pigment layer
Contains collagen and elastin
Drusen can form here
Location: Ciliary body
Runs radially from scleral spur to ora serrata
Function: Ciliary Body (2)
Involved in accommodation as it contains ciliary muscle and anchors lenticular suspensory fibres
Involved in production of aqueous and vitreous
Blood Supply: Ciliary Body
Major arterial circle
Arteries
Layers: Ciliary Body (3)
Supraciliaris
Stroma
Epithelium
Supraciliaris (2)
Transitions from stroma to sclera
Collagen strands with fibroblasts and meloncytes
Stroma (Ciliary Body) (4)
Mostly filled with ciliary muscle
Muscles contract to reduce tension on sensory fibres causing accommodation
Thick walled blood vessels for muscle metabolism
Fenestrated capillaries for supply of constituents for aqueous production
Muscle type of the longitudinal, radial and circular muscles in the ciliary body
Smooth
Epithelium (Ciliary Body) (4)
Double layer cuboidal cells from iris root to retina
Pigmented cells in outer ring of ciliary body
Unpigmented and pigmented in inner ring
Suspensory zonules of crystalline lens extends from basement membrane in outer ring to inner ring
Role of unpigmented cells in the ciliary body epithelium
Modify metabolites from capillaries to secrete aqueous into posterior chamber
What does the cells of ciliary processes contain
Glycogen
4 types of Aqueous Flow
Diffusion
Dialysis
Ultrafiltration
Secretion
Diffusion
Oxygen, carbon dioxide, amino acids, glucose and vitamins travel through cell membrane by diffusion
Dialysis
Permeable capillaries allow through smaller particles and restrict larger
Causes unequal gradient forcing smaller particles to move across to achieve balance
Ultafiltration
Pressure pushes fluid fluid through wall but restricts larger proteins causing imbalance
Produces reverse osmotic effects forcing fluid back into blood vessels
