Human Eye Anatomy, Physiology, Vision Defects, and Language Analysis

Vocabulary flashcards covering the anatomy of the eye, visual physiology, mechanisms of accommodation and pupillary reflexes, optical defects, and English language text analysis.

Photoreceptors

Specialized receptors in the retina that detect and respond to light stimuli.

Orbits

The bony sockets of the skull that house and protect the spherical eye organs.

External Eye Muscles

Muscles that hold the eyeballs in place within the sockets and control eye movements.

Conjunctiva

A thin, transparent membrane that lines the front of the eye over the cornea.

Lachrymal Gland

The gland that secretes antiseptic tears to keep the eye moist and wash away dust.

Sclera

The tough, white outer layer of the eye that protects internal structures and maintains the eyeball's shape.

Cornea

The curved, transparent extension of the sclera at the front of the eye that admits and refracts light to focus an image onto the retina.

Iris

The pigmented part of the eye responsible for eye color, composed of circular and radial muscle fibres that regulate the opening and closing of the pupil.

Pupil

The central opening of the iris through which light enters the interior of the eye.

Ciliary Body

A circular sheet of muscle that alters the shape of the lens during accommodation to focus light.

Suspensory Ligaments

Ligaments that radiate out to the lens, working with the ciliary muscles to change the curvature of the lens for focusing.

Aqueous Humor

The fluid filling the anterior and posterior chambers that refracts light, maintains the shape of the front of the eye, and supplies oxygen ($O_2$) and nutrients.

Lens

A transparent, biconvex body enclosed in an elastic capsule that adjusts its shape to focus light onto the retina for near and distant vision.

Vitreous Chamber

The cavity of the eye filled with a transparent jelly substance that maintains eye shape and assists in light refraction.

Retina

The light-sensitive inner layer of the eye containing photoreceptor cells (rods and cones).

Rod Cells

Photoreceptors in the retina that function in dim or low light and facilitate black-and-white vision.

Cone Cells

Photoreceptors in the retina that function in bright light and are sensitive to color.

Fovea Centralis

The retinal area containing the highest concentration of cones, responsible for the sharpest, clearest vision.

Blind Spot

The region where the optic nerve leaves the eye; it lacks rods and cones, meaning no nerve impulses are generated if light falls there.

Choroid

A vascularized, dark-pigmented layer underneath the sclera that supplies $O_2$ and nutrients to the retina and absorbs light to prevent reflection.

Optic Nerve

A bundle of millions of sensory neurons that carries nerve impulses from the retina to the brain for visual interpretation.

Complex Sentence (Grammar Analysis)

The sentence type represented by 'People follow my page because I'm just my authentic, natural self', which connects an independent clause with a dependent causal clause.

Statistics (Rhetorical Device)

Numerical data integrated by an author (as in paragraphs 4 and 7) to provide factual evidence and enhance the effectiveness of an argument.

Pupil Reflex

An automatic reflex action responding to light intensity to regulate the amount of light entering the eye for protection.

Pupillary Constriction

The pupillary response to bright light in which circular muscles contract and radial muscles relax, narrowing the pupil to admit less light.

Pupillary Dilation

The pupillary response to dim light in which radial muscles contract and circular muscles relax, widening the pupil to admit more light.

Accommodation

The reflex adjustment of the curvature of the lens by ciliary muscles and suspensory ligaments to focus on near or distant objects clearly.

Unaccommodated Eye

The state of the eye at rest when viewing distant objects ($> 6\,m$), where parallel light rays naturally focus onto the retina without adjustment.

Retinal Image Characteristics

The initial visual image formed on the retina, which is both inverted (upside down) and smaller than the actual object before the brain reinterprets it.

Hypermetropia

A vision defect where light rays focus behind the retina because the eyeball is too short or the lens is not sufficiently biconvex.

Myopia

A vision defect where light rays focus in front of the retina because the eyeball is too long or the lens is too biconvex, corrected using biconcave lenses.

Astigmatism

A condition characterized by a blurred retinal image caused by an irregular curvature of the cornea or lens, corrected with ground compensating lenses.

Cataracts

A clouding of the eye's natural lens that scatters incoming light, serving as the leading cause of vision loss among adults aged $55+$ and older.