Vision

Special Senses

Special Senses

Refers to the senses of vision, hearing, taste, smell, and touch that are more specialized and specific in function compared to the general senses.

Accessory Structures

Include eyelids (palpebrae), superficial epithelium of the eye, and the lacrimal apparatus, which provide protection, lubrication, and support to the eye.

Lacrimal Gland

A gland that produces tears to bathe the conjunctival surfaces, containing lysozyme for antibacterial properties and aiding in lubrication and nourishment of the eye.

Fibrous Layer

The outermost layer of the eyeball consisting of the sclera (white of the eye), cornea (transparent portion), and corneoscleral junction (border between cornea and sclera).

Vascular Layer (Uvea)

The intermediate layer of the eye that includes the iris, ciliary body, and choroid, responsible for regulating light entry, secreting/reabsorbing aqueous humor, and controlling lens shape.

Retina

The inner neural layer of the eye that contains photoreceptors and processes visual information before sending it to the brain for interpretation. Innermost layer of the eyeball, consisting of the pigmented layer and the neural layer with photoreceptors.

Ciliary Body

Part of the eye that attaches to the iris, contains ciliary processes and muscle, and changes the lens curvature.

Iris

Colored part of the eye that contains the pupil and determines eye color.

Choroid

Vascular layer in the eye that supplies oxygen and nutrients to the retina.

Photoreceptors

Cells in the retina that detect light, including rods for dim light and cones for color vision.

Bipolar Cells

Neurons in the retina that connect rods and cones to ganglion cells.

Ganglion Cells

Cells in the retina that transmit visual information to the brain via the optic nerve.

Optic Disc

Area in the retina where the optic nerve originates, creating a blind spot.

Macula Lutea

Area of the retina with a high concentration of cones.

Fovea

Central area of the macula with the highest concentration of cones for sharp vision.

Aqueous Humor

Fluid in the eye's chambers that provides nutrients and maintains intraocular pressure.

Vitreous Body

Gelatinous mass in the posterior cavity that stabilizes the eye shape.

Lens

Structure in the eye held by the suspensory ligament, responsible for focusing light on the retina.

Refraction

Bending of light as it passes through different mediums like the cornea and lens.

Cataracts

Opacities in the lens leading to loss of transparency, often associated with aging. Cloudy lens condition that can result from various factors like age, UV light exposure, injuries, or drugs, and is treated by removing the lens and replacing it with an artificial one.

Astigmatism

Condition where light is not refracted properly, causing distorted vision. Uneven focusing due to irregular corneal curvature, corrected by using a cylindrical lens.

Accommodation

The adjustment of the lens in the eye to focus on objects at different distances. Ability of the lens to adjust shape for focusing on objects at different distances.

Ciliary Muscle

A muscle in the eye that controls the shape of the lens for focusing.

Hyperopia

Farsightedness, where distant objects are seen more clearly than close ones.

Myopia

Nearsightedness, where close objects are seen more clearly than distant ones.

Presbyopia

Age-related farsightedness due to the loss of lens elasticity.

Refractive Problems

Issues related to the focusing of light in the eye.

Rods

Photoreceptor cells in the eye sensitive to low light conditions.

Cones

Photoreceptor cells in the eye responsible for color vision and detail.

Rhodopsin

The photopigment in rods responsible for vision in low light.

Color Vision

The ability to perceive different colors, primarily enabled by cones in the eye.

Visual Acuity

The sharpness of vision, with greater acuity in cone vision due to the 1:1 ratio of cones to ganglion cells in the fovea.

Rod Vision

Vision where many rods may stimulate the same ganglion cell, resulting in a larger area of the retina signaling that ganglion cell.

Optic Nerve

The bundle of axons of ganglion cells that leave the eye at the optic disc.

Optic Chiasma

The point where axons carrying information from the lateral field of each eye cross over to the optic tract of the other side.

Detached Retina

Condition where the neural portion of the retina separates from the underlying tissue, leading to out-of-focus images and potential blindness, treated via surgery or silicone oil placement.

Macula Degeneration

Gradual destruction of cells in the fovea leading to loss of visual acuity, a major cause of blindness in older adults.