Lecture 20: Eye Histology Flashcards
What is the function of the eyelid?
Protects the eye
What is the function of tarsal glands?
Special sebaceous glands that produce meibum to prevent evaporation of of tears
What can blocked tarsal glands lead to?
Chalazion
Lump on eyelid
What can blocked sebaceous glands in the eyelashes lead to?
Stye
Near eyelash follicles
What do lacrimal glands do?
Produce tears
Made from tubuloacinar serous glands
What is the conjunctiva that lines the outermost part of the eyeball?
Bulbar (ocular) Conjunctiva
What is the conjunctiva that lines the innermost part of the eyelids?
Palpebral Conjunctiva
What is the anterior chamber between?
Between Cornea and Iris
Filled with aqueous humor
What is the posterior chamber between?
Between Iris/Pupil and Lens (small)
What is vitreous chamber between?
Lens and neural retina
Filled with vitreous humor to maintain shape
What structures compose the fibrous (external) layer of the eye?
- Sclera: supports eye and protects internal structure
- Cornea: protects anterior surface of eye and refracts light
What are the five layers of the cornea, anterior to posterior?
- Corneal Epithelium: nonkeratinized statified squamous
- Bowman’s Membrane: anterior basement membrane
- Corneal Stroma: avuscular and 60 layers thick
- Descemet’s Membrane: posterior basement membrane
- Corneal Endothelium: faces anterior chamber
What is found in between the basement membrane and corneal epithelium?
Free Nerve Endings
What structures compose the vascular (middle) layer of the eye?
- Choroid: supplies nourishment to retina
-
Ciliary Body
- Ciliary Muscle: manages accomodation
- Ciliary Processes: secretes aqueous humor and and forms suspensory ligaments oflens
- Iris: controls light entering eye
What are the layers of the lens?
- Capsule
- Subcapsular Lens Epithelium
- Lens Fibers
What is accommodation?
How is this accomplished?
Ciliary muscles adjust eyes to see objects at various distances
- Distant objects: flatten lens
- Neaby objects: rounded lens
Zonular fibers help lens change its shape
What is presbyopia?
Loss of lens elasticity with age
What structures compose the internal layer of the eye?
- Pigmented layer: absorbs light and serves as a blood-neural retinal barrier
- Neural layer: where light is converted in nerve signals
What is the optic disk?
Blind spot in retina where optic nerves from ganglion layer exit eye
What are the layers of the retina?
- Retinal Pigmented Layer (most posterior)
- Photoreceptor Layer: Rods and Cones
- Outer Limiting Layer
- Outer Nuclear Layer
- Outer Plexiform Layer
- Inner Nuclear Layer
- Inner Plexiform Layer
- Ganglion Layer
- Optic Nerve Fiber Layer
- Inner Limiting Membrane: Muller Cells
What is fovea centralis?
Highest concentration of cones with the sharpest visual acuity
What is the macula lutea?
Surrounds fovea and protects cone
What does the optic nerve penetrate to travel to the brain?
Choroid and sclera
