eye Flashcards
how does sight work
Light passes through cornea, pupil, lens, and vitreous body to stimulate sensory receptors (rods and cones) on the retina.
emmetropia
normal
normal
emmetropia
orbit
Cavity lined with fatty tissue that contains and cushions the eyeball.
Has several openings through which blood vessels and nerves pass.
muscles
Six short muscles provide support and rotary movement of the eyeball.
Connect the eyeball to the orbital cavity.
Four muscles are straight (rectus) muscles and two are slanted (oblique) muscles.
eyelids
Protect the eyeballs from intense light, foreign particles, and impact.
Edges have eyelashes and sebaceous glands, which secrete sebum into the eyelids.
conjunctivia
Mucous membrane that lines the underside of the eyelid and anterior surface of the eyeball.
Protective covering for the exposed surface of the eyeball.
lacrimal apparatus
Includes structures that produce, store, and remove the tears that cleanse and lubricate the eye.
Structures include: Lacrimal gland, ducts and canals.
eyeball
organ of vision
composed of 3 sections
eyeball- outer layer
Composed of the sclera and the cornea.
Posterior portion is the sclera (white)
Anterior portion is the cornea (transparent)
sclera
White” of the eye
cornea
Anterior transparent portion of the eye’s fibrous outer surface.
Surface is curved, allowing it to bend light rays to focus them on the retinal surface.
eyeball- middle layer
Lies below the sclera.
Consists of: Choroid, Ciliary Body and Iris.
choroid
Pigmented, vascular membrane.
Prevents internal reflection of light.
ciliary body
Thickened part of the vascular membrane.
Iris is attached.
Part of the ciliary body governs the convexity (curve) of the lens.
Secretes the aqueous humor (nutrient fluids) that nourish the cornea, the lens and surrounding tissues.
iris
Coloured membrane attached to the ciliary body.
Suspended between the lens and the cornea in the aqueous humor.
Circular opening in centre called the pupil.
Has 2 muscles which dilate or contract to regulate the amount of light admitted by the pupil
eyeball- inner layer
Contains: Lens and Retina.