Special Senses: The Eye 1/2

Photoreceptors

Cells capturing light stimuli for vision.

1. Anterior chamber

2. Posterior chamber

3. Aqueous humor

4. Pupil connects the chambers

What is contained in the anterior cavity of the eye?

Contains the vitreous body (CT)

and vitreous humor

What is contained in the posterior cavity (vitreous cavity)?

Surrounded by retina

(posterior to the lens and zonula fibers)

What is the vitreous cavity surrounded by?

Fibrous Tunic (Corneosclera)

Outermost layer of the eyeball. Includes sclera + cornea

Episclera

Sclera proper

Suprachroid lamina (lamina fusca)

3 layers of sclera in order from outermost to innermost?

Mnoemnic for sclera layer

Every Strong Layer Forms"

Episclera – Sclerap proper – Lamina Fusca

Thin layer, abundant microvasculature, and loose CT.

Fibroblasts, macrophages, and lymphocytes.

The outermost layer of sclera (episclera) has what characteristics?

Dense connective tisssue

The episclera has loose connective tissue, while the scleara proper has ? (CT)

Sclera proper

Contains type 1 collagen and is avascular

Suprachroid lamina (lamina fusca)

Has less collagen, more fibroblasts, elastic fibers, and melanocytes

the cornea

What makes up the anterior 1/6 of the eye?

Cornea

Transparent, avascular, anterior part of the fibrous tunic.

1. Corneal epithelium

2. Bowman's membrane

3. Corneal stroma

4. Descemet's membrane (posterior limiting membrane)

5. Corneal endothelium

Layers of the cornea?

Corneal Epithelium

Non-keratinized stratified squamous cells, protective layer.

the conjuctival epithelium*

The corneal epithelium is continous with what? *

Rich sensory nerve supply

the corneal epithelium has a rich supply of?

Bowman's Membrane

Thick basement membrane, supports cornea structure.

Protects stroma against infections

The bowman's membrane protects against?

at the limbus

where does Bowman's membrane end?

Corneal Stroma

Thickest layer of cornea (90%), also known as substance proprietary.

Collagen fibrils and sheets of flattened fibroblasts in between

The corneal stroma has lamellae that contains what substance?

Descemet's Membrane

Basement membrane of endothelium. (endothelium rests on this membrane)

Corneal Endothelium

Simple squamous layer, maintains Descemet's membrane.

Corneal endothelium

Where do you find cells that are the most metabolically active cells of the cornea? *

Through Na+K+ ATPase pumps

How does the corneal endothelium regulate hydration of the corneal stroma?

A:Bowman's membrane

P: Descemet's membrane (it is thinner than Bowman's)

What is the anterior limiting membrane? posterior limiting membrane?

E – Epithelium (outermost layer)

B – Bowman's layer

S – Stroma (thickest layer)

D – Descemet’s membrane

E – Endothelium (innermost layer)

"Eager Boys Slide Down Easily"

Limbus

Transition zone between cornea and sclera. Encircles the cornea

The conjunctiva

When the surface of limbus becomes more stratified what does it form?

It becomes vascular and less well-organized

How does the stroma change in the limbus?

trabecular meshwork

In the limbus, what structure replaces the endothelium and descemet's membrane?

Trabecular meshwork

Allow slow and continuous drainage of aqueous humor

Schlemm canal (scleral venous sinus)

Channels of the meshwork convey aqueous humor to the _______ ________ ?

Uvea

What is the most vascular layer of the eye?

Choroid (posterior)

Ciliary body

Iris (anterior)

3 parts of the uvea include (vascular layer)

Choroid

Posterior 2/3 of the eye

Well vascularized, loose CT, with melanocytes

what type of tissue does the choroid have?

Choroidocapillary lamina (innermost)

Bruch membrane

What are the two layers of the choroid?

ciliary body

anterior expansion of uvula (vascular layer) that encirlces the lens

posterior to the limbus; b/t the iris and choroid

the ciliary body is posterior to the what

Ciliary muscle

Ciliary processes

Ciliary zonule

Three regions of the ciliary body:

Meridional or longitudinal portion

Radial or oblique portion

Circular or sphincteric portion

Three smooth muscle fibers in C. muscle:

Radial or oblique portion

Deep muscle fibers. Insert in the ciliary body

Flattening of the lens for distance vision (increases tension)

Contraction of the radial/oblique portion leads to:

Circular or sphincteric portion

Inner bundle muscle fibers, circular arrangement

Thickening of the lens for near vision (reduces tension)

Contraction of the circular portion leads to:

Ciliary processes

Radially arranged series of 75 ridges that extend from vascular region of the CB

Stratified columnar epithelium (where aqueous humor is secreted)

The ciliary processes are covered by what type of epithelia?

The pigmented epithelium of the retina

The pigmented inner layer of the ciliary processes is continuous with:

Sensory layer of the retina

The superficial layer of ciliary processes is continuous with:

Superficial layer lacks melanin

What does the superficial layer of ciliary processes NOT have?

Fibrillin 1 and 2 that holds the lens in place

what type of fibrillin does the ciliary zonule contain?