Vision - The Eye Flashcards

Flashcards about Vision and the Eye based on Neuroscience lecture notes.

What is vision?

Detection of electromagnetic radiation (light) by our visual system.

What are photoreceptors?

Structures that are sensitive to and detect light.

What is electromagnetic radiation (ER)?

Waves of electric and magnetic disturbances traveling through the universe at the speed of light.

What is wavelength?

The distance between one peak to the next in an ER wave.

What is the relationship between wavelength and energy?

The shorter the wavelength, the higher the energy.

What is reflection?

Light bouncing off a surface.

What is absorption?

Transfer of light energy to a surface.

What is refraction?

Bending of light traveling through a transparent medium.

What is the anterior chamber of the eye?

The chamber between the cornea and the iris that contains aqueous humor.

What is the posterior (vitreous) chamber of the eye?

The largest chamber of the eye that contains vitreous humor.

What are the three layers of the eye?

Fibrous layer, vascular layer, and sensory layer.

What does the fibrous layer consist of?

Sclera and cornea.

What does the vascular layer consist of?

Ciliary body, iris, and choroid.

What is the sensory layer of the eye?

Retina.

What retinal structures can be seen through an ophthalmoscope?

Optic disk, macula, and fovea.

What is the function of the optic nerve (CN II)?

Carries visual sensory information from the retina to the brain for processing.

What are the three pairs of extraocular muscles?

Medial and lateral rectus, superior and inferior rectus, and superior and inferior obliques.

What does the oculomotor nerve (CN III) innervate?

Levator palpebrae, medial rectus, superior and inferior rectus, inferior oblique, and muscles involved in pupillary light reflex and accommodation.

What does the trochlear nerve (CN IV) innervate?

Superior oblique.

What does the abducens nerve (CN VI) innervate?

Lateral rectus.

What is astigmatism?

Unequal curvature of the cornea (or lens).

What is a cataract?

Clouding of the lens that causes visual distortion.

What is myopia?

Nearsightedness (far objects blurry) caused by the eye being too long.

What is hyperopia?

Farsightedness (near objects blurry) caused by the eye being too short.

What muscles control the pupillary light reflex?

Sphincter pupillae and dilator pupillae.

What are the cells of the retina?

Rods, cones, ganglion cells, bipolar cells, amacrine cells, horizontal cells, and melanocytes.

What are the layers of the retina?

Ganglion cell layer, inner plexiform layer, inner nuclear layer, outer plexiform layer, outer nuclear layer, photoreceptor outer segments, and pigmented epithelium.

What is the structure of rod photoreceptors?

Long, cylindrical outer segment with many disks containing photopigments.

What is the structure of cone photoreceptors?

Shorter, cone-shaped outer segment with fewer disks.

What is phototransduction?

Conversion of light energy into changes in membrane potential.

What are the steps of phototransduction in rods?

Rhodopsin activates G-protein (transducin), transducin activates enzyme (phosphodiesterase), phosphodiesterase phosphorylates cGMP to convert it to GMP, reduction in cGMP levels causes Na+ channels to close (hyperpolarization of membrane, inactive).

What are the three opsin photopigments in cones and their corresponding wavelengths?

Blue cones (430nm), green cones (530 nm), and red cones (560 nm).

What is the optic disk?

Location on the retina where the optic nerve exits the eye; lacks photoreceptors, creating a blind spot.

What is the macula?

Yellowish region near the center of the retina, critical for high-acuity vision.

What is the fovea?

Central pit within the macula, containing a high density of cones and responsible for the highest visual acuity.

What is myopia?

Nearsightedness.

What is hyperopia?

Farsightedness.

What is presbyopia?

Age-related decline in accommodation, leading to difficulty focusing on near objects.

What is accommodation?

The ability of the eye to change its focal length.

What is the optic chiasm?

The crossing of the optic nerves from each eye at the base of the brain.

What is the visual cortex (V1)?

The primary visual cortex located in the occipital lobe of the brain, responsible for processing visual information.

What are simple cells?

Neurons in the visual cortex that respond to specific orientations of lines or edges.

What are complex cells?

Neurons in the visual cortex that respond to lines or edges with a particular orientation, regardless of their exact location.

What is parallel processing?

The processing of multiple features of an object (e.g., color, form, motion) in different areas of the brain to create a unified perception.

What are the dorsal and ventral streams?

The dorsal pathway (where) processes spatial information and object location; the ventral pathway (what) processes object recognition and identification.

What is neural plasticity?

The ability of the brain to reorganize neural pathways based on experience, especially after injury or deprivation.

What is prosopagnosia?

A condition characterized by deficits in face recognition, despite otherwise normal visual processing.

What is synesthesia?

A rare neurological disorder in which stimulation of one sensory or cognitive pathway leads to automatic, involuntary experiences in a second sensory or cognitive pathway.

What are smooth pursuit eye movements?

Eye movements that maintain focus on a moving object.