BI 342: Lab 5

Optic nerve

Axons that leave eye and relay visual information to brain

Aqueous humor

Provide nutrients to cornea, lens

Lens

Refract, focus light

Suspensory ligament

Hold lens, adjust lens shape with ciliary body

Vitreous humor (body)

Maintain pressure on retina

Pupil

Adjust light amount that reaches retina (changes due to iris muscle activation)

Sclera (fibrous tunic)

Site of muscle attachment, protect, anchor eye

Cornea (fibrous tunic)

Refract light

Choroid (vascular tunic)

Provide nutrients to retina

Ciliary body (vascular tunic)

Smooth muscle that adjusts shape of lens to bend light to fovea

Iris (vascular tunic)

Trap excess light, muscles that change size of pupil

Ora serrata (vascular tunic)

Site where ciliary body meets choroid

Retina (sensory tunic)

Responsive to light, phototransduction

Optic disc (sensory tunic)

Site of axons leaving eye, vessels entering; blind spot

Macula lutea (sensory tunic)

Site of many cones, contains fovea centralis

Fovea centralis (sensory tunic)

Focal point, highest density of cones (no rods) where bright light is focused to for sharpest resolution

Photoreceptors (cones, rods) (part of retina)

Responsive to light energy, relay signal to bipolar cells

Bipolar cells (part of retina)

Neuron in chain between photoreceptor and ganglion cell

Ganglion cells (part of retina)

Neurons that receive information from bipolar cells, axons make up optic nerve, carry signals to brain for visual processing

Blind spot

optic disc, where the optic nerve exits the eyeball, contains no photoreceptors and so should light hit this area, nothing is seen

Visual acuity

one's ability to distinguish separate images in the visual field

Astigmatism

a defect in the eye or in a lens caused by a deviation from spherical curvature, which results in distorted images, as light rays are prevented from meeting at a common focus

Myopia

nearsightedness; near objects are clearly seen, far are not

Hyperopia

farsightedness; near objects are not clear seen, far are

Afterimages

persistent signaling in the visual system despite removal of the stimulus; caused by ongoing bleaching of photopigments

Bleaching

photopigment degeneration caused by light stimuli; triggers signaling in visual pathway

Color blindness

a reduced ability to distinguish between different colors, associated with inability to produce certain cone photopigment or have functional cones; caused by genetic variation

Accommodation

changes in lens shape and pupil diameter to adjust for focusing light to appropriate areas on the retina for seeing clearly

Convergence

medial rotation of eyes for close up objects

Depth perception

ability of person to determine relative distance of objects in visual field

Visual field

the area that can be seen with eyes and head in fixed position

Optic chiasm

location where optic nerves merge; some fibers cross over to contralateral side of brain, some do not

Optic tract

Neuron axons from optic chiasma to thalamus

Optic radiation

Neuron axons from thalamus to occipital lobe

Visual field defect

inability to see certain areas of visual field