Uveal Tract

Question 1

Iris: Location

Answer 1

Separates anterior and posterior chambers

Question 2

Iris: Function

Answer 2

Varies aperture of pupil to control the amount of light focusing on the retina

Question 3

Diameter: Iris

Answer 3

~13mm

Question 4

Thickness: Iris

Answer 4

0.1mm at root

0.6mm at collarette

Question 5

Diameter: Pupil

Answer 5

1-8mm (varies in different lighting)

Question 6

Blood Supply: Iris

Answer 6

Major arterial circle in ciliary body - ends with capillary loops at pupil margin

Question 7

Blood Drainage: Iris

Answer 7

Ciliary plexus

Question 8

Nerve Supply: Iris

Answer 8

Long and short ciliary nerves from nasociliary branch of ophthalmic division of trigeminal nerve

Question 9

Layers: Iris (3)

Answer 9

Anterior Border Layer

Stroma

Epithelium

Question 10

Anterior Border Layer (iris) (3)

Answer 10

More melanocytes = velvety brown texture

Less pigment in Cryts of Fuch

Fibroblasts and meloncytes

Question 11

Stroma (iris) (3)

Answer 11

Collagen connective tissue

Blood vessels

Iris sphincter muscle

Question 12

Muscle type: Iris Sphincter Muscle

Answer 12

Smooth

Question 13

Epithelium (iris) (3)

Answer 13

Pupil ruff

Dilator pupillae muscle

Densely packed melanin

Question 14

Purpose of melanin in epithelium (iris)

Answer 14

Absorbes light

Question 15

Choroid: Location

Answer 15

Sandwiched between outer sclera and inner retina from ora serrata to edge of optic nerve

Question 16

Choroid: Function (4)

Answer 16

Allows for metabolic exchange

Waste removal to and from photoreceptors

Regulates temperature of globe

Deep pigment layer to absorbe light

Question 17

Choroid: Blood Supply (2)

Answer 17

Major arterial circle

Circle of Haller-Zinn

Question 18

Layers: Choroid (4)

Answer 18

Suprachoroid

Stroma

Choriocapillaris

Basal Lamina

Question 19

Suprachoroid (4)

Answer 19

Outer layer

30um thick with structural link of collagen fibrils with sclera

Contains meloncytes and fibroblasts

Route for nerves and blood vessels

Question 20

Stroma (choroid) (2)

Answer 20

Pigment layer

Highly vascular

Question 21

Choriocapillaris (3)

Answer 21

Single layer of wide capillaries

Lies flat against base layer

Thickness and internal blood pressure to counter act intraocular pressure

Question 22

Basal Lamina (4)

Answer 22

2-4um thick

Smooth layer for retinal pigment layer

Contains collagen and elastin

Drusen can form here

Question 23

Location: Ciliary body

Answer 23

Runs radially from scleral spur to ora serrata

Question 24

Function: Ciliary Body (2)

Answer 24

Involved in accommodation as it contains ciliary muscle and anchors lenticular suspensory fibres

Involved in production of aqueous and vitreous

Question 25

Blood Supply: Ciliary Body

Answer 25

Major arterial circle Arteries

Question 26

Layers: Ciliary Body (3)

Answer 26

Supraciliaris Stroma Epithelium

Question 27

Supraciliaris (2)

Answer 27

Transitions from stroma to sclera Collagen strands with fibroblasts and meloncytes

Question 28

Stroma (Ciliary Body) (4)

Answer 28

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

Question 29

Muscle type of the longitudinal, radial and circular muscles in the ciliary body

Answer 29

Smooth

Question 30

Epithelium (Ciliary Body) (4)

Answer 30

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

Question 31

Role of unpigmented cells in the ciliary body epithelium

Answer 31

Modify metabolites from capillaries to secrete aqueous into posterior chamber

Question 32

What does the cells of ciliary processes contain

Answer 32

Glycogen

Question 33

4 types of Aqueous Flow

Answer 33

Diffusion Dialysis Ultrafiltration Secretion

Question 34

Diffusion

Answer 34

Oxygen, carbon dioxide, amino acids, glucose and vitamins travel through cell membrane by diffusion

Question 35

Dialysis

Answer 35

Permeable capillaries allow through smaller particles and restrict larger Causes unequal gradient forcing smaller particles to move across to achieve balance

Question 36

Ultafiltration

Answer 36

Pressure pushes fluid fluid through wall but restricts larger proteins causing imbalance Produces reverse osmotic effects forcing fluid back into blood vessels