Vision and Eye Anatomy Lecture Review

Flashcards covering the anatomy of the eye, visual processing, photoreceptor functions, color vision theories, and related phenomena presented in the lecture notes.

Sclera

The tough white covering around the eye that helps it maintain its shape and protects it from damage.

Cornea

The clear, rounded front portion of the sclera that acts as a window, allowing light to enter the eye and bending it to focus the image.

Nearsightedness

A vision condition where the cornea is too rounded, causing the image to focus too far in front of the back of the eye, resulting in blurry distant vision.

Farsightedness

A vision condition where the cornea is too flat, causing the image to focus too far behind the back of the eye, resulting in blurry close-up vision.

Astigmatism

A vision condition caused by an imperfectly smooth, wavy cornea, leading to double vision on the back of the eye.

Aqueous Humor

The fluid-filled space located just behind the cornea.

Iris

The colored ring in your eye that manages the amount of light entering the eye by expanding in bright light and constricting in dim light.

Pupil

The black spot in the middle of the iris, which is actually a hole controlled by the iris to regulate light entry.

Lens

A structure responsible for helping to focus on objects, changing shape in a process known as accommodation.

Accomodation

The process of the lens changing in shape to focus on an object that is close to the eye (within about four feet).

Vitreous Humor

The fluid-filled space behind the lens where pressure problems like glaucoma can develop with age.

Retina

The layers of cells at the very back of the eye that make up a structure responsible for transforming light energy into neural signals.

Ganglion Cells

The first layer of cells in the retina (closest to the front of the eye) that become the optic nerve, sending information to the brain.

Bipolar Cells

The middle layer of cells in the retina that synapse with ganglion cells and photoreceptors, sending signals between them.

Sensory Receptor

A specialized neuron capable of transforming some other kind of energy (like light) into a neural signal.

Photoreceptors

A subcategory of sensory receptors in the retina that are capable of transforming light energy into a neural signal (rods and cones).

Blind Spot

A small area in each eye where the optic nerve leaves the eye, containing no photoreceptors and thus no visual information.

Fovea

The pit-like area at the center of your visual field, where you actively look at things and where cones are most concentrated for clear, detailed vision.

Rods

A type of photoreceptor, numbering around 100 million per eye, that are highly sensitive to low levels of light and primarily responsible for vision in dim conditions (black and white vision).

Cones

A type of photoreceptor, numbering around 6.5 million per eye, that are responsible for seeing fine detail and processing color, performing best in brighter light.

Photopigment

A light-reactive chemical contained within rods and cones (made of retinal and opsin) that breaks apart when light hits it, initiating a neural signal.

Rhodopsin

The photopigment found in rods, which is extremely reactive to even small amounts of light.

Dark Adaptation

The process of adjusting to very low levels of light, involving the rebuilding of photopigments in rods (taking about 30-35 minutes) to increase sensitivity.

Spectral Sensitivity Curves

Graphs that show what wavelengths specific cells (like rods or various types of cones) respond best to.

Bleaching

The process where photopigment is broken down in the eye by exposure to light, causing it to lose its color and initiating a neural signal.

Trichromatic Theory

A theory of color perception stating that there are three different types of cones (red, green, blue), each sensitive to different wavelengths of light, and their combined activity determines the perceived color.

Opponent Process Theory

A theory of color vision that explains phenomena like afterimages, suggesting that ganglion cells process color in opposing pairs (red-green, blue-yellow, black-white).

Red On Green Off Cell

A type of ganglion cell where the red cone sends excitatory information and the green cone sends inhibitory information, leading to a signal when red light is dominant.

Blue On Yellow Off Cell

A type of ganglion cell where the blue cone sends excitatory information and the yellow (result of red+green activation) sends inhibitory information.

On Center Cells

Ganglion cells that receive excitation when light falls on the center of their receptive field and inhibition when light falls on the surrounding area, making them highly responsive to bright dots on dark backgrounds.

Off Center Cells

Ganglion cells that receive inhibition when light falls on the center of their receptive field and excitation when light falls on the surrounding area, making them highly responsive to dark dots on bright backgrounds.

Bar Detectors

Cells in the primary visual cortex that are orientation-specific, responding only to lines of a particular angle (e.g., vertical, horizontal, angled).

Optic Chiasm

The 'X' shaped structure where half of the visual information from each eye crosses over to the opposite hemisphere of the brain.

Color Blindness

A condition resulting from a misspelling or deletion of genes coding for photopigments in the red, green, or blue cones, primarily affecting individuals with a single X chromosome (males).