The Eye

Flashcards for eye anatomy and physiology review.

Eyes

Photosensitive organs for analyzing form, intensity, and color of light reflected from objects.

Outer Fibrous Layer

Tough external fibrous layer of the eye consisting of the sclera and cornea.

Uvea

Middle vascular layer of the eye, including the choroid, ciliary body, and iris.

Retina

Inner sensory layer of the eye that communicates with the cerebrum through the optic nerve.

Extraocular Muscles (EOM)

Muscles responsible for controlling the movements of the eyeball and upper eyelid.

Conjunctiva

Clear membrane covering the surface of the eye and inner eyelids.

Inner mucus layer

Keeps the whole tear fastened to the eye.

Watery middle layer

Keeps the eye hydrated, repel bacteria and protect the cornea.

Outer oily layer

Keeps the surface of the tear smooth for the eye to see through, and to prevent the other layers from evaporating

Contents Enclosed by Eye Coats

Optically clear aqueous humor, lens, and vitreous body.

Outermost coat of eye

Cornea and the sclera.

Middle Coat of the Eye

Choroid, the ciliary body, and the iris.

Developing eyes

Appears in the 22-day embryo as an optic grooves on sides of forebrain

Optic vesicle invaginates

Forms optic cup

choroid fissure

Allows hyaloid artery to reach inner chamber of the eye

neuroectoderm,surface ectoderm, and mesoderm

Tissue that form the eye are derived from

Inner layer of optic cup

Forms the neural retina

Outer layer of optic cup

Becomes the RPE(retinal pigmented epithelium)

Mesenchyme surrounding the optic cup

Gives rise to the sclera

Invagination of central region of each lens placode

Forms the lens vesicles

Connection between optic and diencephalic vesicles

Attaches to brain and becomes the optic nerve

Front surface of the optic vesicle

Becomes the neural retina

Back surface of the optic vesicle

becomes the retina's pigmented epithelium

Mesenchyme extending into invagination of the optic cup

Becomes the vitreous component of the eye

Mesenchymal shell at outer surface of the optic cup

Differentiates into vascular choroid coat of the eye and fibrous components of the sclera and cornea

Cornea

Transparent.

Sclera

Opaque.

Episclera

A thin, loose, collagenous connective tissue.

Limbus

Location of corneal stem cell

Sclera

Dense connective tissue made of mainly type 1 collagen fibers, oriented in different directions

Lamina Cribrosa (LC)

Mesh-like structure at the optic nerve head that surrounds and supports the retinal ganglion cell axons as they form the optic nerve.

Bowman’s Membrane

Homogeneous-appearing layer on which the corneal epithelium rests.

Descemet’s Membrane

Unusually thick basal lamina of the cornea.

Corneal Stroma

Composed of about 60 thin lamellae.

Uvea

The vascular layer in the middle, subdivided into the iris, ciliary body, and choroid.

Limbus

Transitional area where the transparent cornea merges with the opaque sclera.

Limbus

Encircling the cornea.

Ciliary body

ring of smooth muscle fibers arranged concentrically around the opening in which the lens is suspended

Zonular fibers

Extend from the ciliary epithelium toward the lens

Cells of this dual epithelium

Have extensive basolateral folds with Na+/K+-ATPase activity and are specialized for secretion of aqueous humor

Dilator Pupillae Contraction

Causes Pupil dilation, or mydriasis.

Ciliary Processes Produce

Aqueous humor

Bruch's Membrane

Thin (2–4 µm), acellular, five-layered extracellular matrix located between the retina and choroid.

The Lens

Transparent biconvex structure held in place by a circular system of zonular fibers and close apposition to the posterior vitreous body.

Lens Capsule

A thick, homogenous external lamina composed of proteoglycans and type IV collagen that surrounds the lens

Vitreous humor

Helps maintain the round shape of the eye and can also help with vision clarity and shock absorbance

Lacrimal Glands

the tear glands located above each eyeball, continuously supply tear fluid that's wiped across the surface of your eye each time you blink your eyelids

Neural Retina

Inner layer of the retina that contains the photoreceptor cells.

Fovea centralis

Shallow depression located about 2.5 mm lateral to the optic disc

Radial branches from blood vessels on the retinal surface

Are interconnected by capillary beds present in the inner layers of the retina

Photoreceptor Layer

Innermost layer of the retina containing photoreceptors (rods and cones).

Function of Rods and Cones

Rods are responsible for vision in low light, cones for color vision in bright light.

Inner Nuclear Layer

Layer containing bipolar cells, horizontal cells, and amacrine cells.

Function of Bipolar Cells

Relay signals from photoreceptors to ganglion cells.

Function of Horizontal Cells

Modulate signals between photoreceptors and bipolar cells.

Function of Amacrine Cells

Influence signals between bipolar and ganglion cells.

Ganglion Cell Layer

Layer containing the cell bodies of ganglion cells, which send axons to the brain.

Optic Nerve Fiber Layer

Axons of ganglion cells that converge to form the optic nerve.

Fovea

Specialized for high-acuity vision; contains a high density of cones and no rods.

Optic Disc

Area where the optic nerve exits the eye; lacks photoreceptors, creating a blind spot.

Optic Disc Location

2.5 mm nasal to the fovea.

Retinal Blood Vessels

Supplies nutrients and oxygen to the retina.

Origin of Retinal Vessels

Arise from the central retinal artery and vein.

Phototransduction

A neural process of converting light into electrical signals.

Rods in Phototransduction

Contain pigment rhodopsin that is activated by light.

Cones in Phototransduction

Contain different opsins sensitive to different wavelengths of light (red, green, blue).

Process of Phototransduction

Initiated by light absorption, leading to a cascade of biochemical reactions that hyperpolarize the photoreceptor cell.

Transmission of Visual Signals

Transmitted from photoreceptors through bipolar cells to ganglion cells.

Function of Ganglion Cells

Form the optic nerve and transmit signals to the brain.