Physiology- Vision & Auditory Unit

Sclera Functions (2)

• Provide strengths & flexibility

• Covers majority of eye’s exterior

Sclera Important Details (3)

• Contains collagen (strength) fibers

• Contains elastic (flexibility) fibers

• Is white

Sclera Functions (2)

• Provide strengths & flexibility

• Covers majority of eye’s exterior

Sclera Important Details (3)

• Contains collagen (strength) fibers

• Contains elastic (flexibility) fibers

• Is white

Choroid Functions (2)

• Intermediate layer

• Provides oxygen & nutrients to retina

Choroid Important Details

• Blood vessels

• Vascular

Retina Functions (2)

• Innermost layer of eye

• Focused image lands here

Retina has ____&____

cones & rods

Cones

Color vision (sensory neurons)

Rods

Vision in low lighting (sensory neurons)

Fovea Function

Provides highly detailed vision

Fovea Contains _____ _____

ONLY Cones

Optic Disc Functions (2)

• Blind Spot

• Location where optic nerve connects to retina.

Optic Disc is area where

No photoreceptors are found.

Cornea Functions (2)

• Covers anterior of eye

• Lets light enter through pupil.

Cornea Important Detail

Transparent

Iris Functions (2)

• Regulates amount of light entering eye.

• Provides color to eye.

Iris important detail

Smooth muscle

Pupil Function

Opening through which light enters.

Pupil Important details (2)

• Bright Light: Smaller opening (constrict)

• Dim Light: Larger opening (dilating)

Lens Function

Bends light to focus the image

Bend means

Refract

Accomodation

lens ability to change shape

Lens Important Details (2)

Near by objects: Thicker

Far away objects: Thinner

Internal components (2)

• Aqueous humor

• Vitreous humor

Aqueous humor function

Provides nutrients to avascular structures & removes waste.

Vitreous humor Function

Maintains shape of eye

Aqueous humor important detail

Watery

Vitreous humor important detail

jelly like

External components (2)

• Optic nerve

• Optic muscles

Optic nerve function

Carries info to brain

Optic muscles

Moves the eye voluntarily

Optic nerve important detail

Sensory neuron

Optic muscles important detail

Skeletal muscle

Binocular Vision (3)

• Overlapping fields of vision of two eyes.

• Each eye sees slightly diff, image & brain processes this into one image.

• Gives depth perception to our image.

Depth Perception (2)

• 3 Dimensional imaging

• Allows individual to better understand spatial awareness ( near & far objects)

Vision Sensory Neurons: Rods (4)

• More neurons

• Only one type

• Used in darkness or low lighting

• Detect light

Vision Sensory Neurons: Cones (4)

• Fewer cones that rods

• 3 types: red, green, blue

• Used during day or well lit environments.

• Detect color (based on combination of which cones are activated

Snellen Chart (3)

• Test visual acuity of a person

• Test for myopia

• Reading chart

Visual acuity

Amount of detail a person can see.

Myopia

Nearsightedness (can see near objects but not far)

Reading chart top #

Distance person is from chart

Reading chart bottom #

Distance a “normal” eye can see at top #.

Bind spot (2)

Where light rays converge (land) on optic disc.

No photoreceptors present: no stimulation of neurons, no electrical impulse, no image seen.

Astigmatism Chart

Cornea or lens have IRREGULAR shape: makes light rays spread out, causes blurry vision

Peripheral Vision (3)

Side vision when a person is looking straight

Exam results: Distinguish black/white vision is better than red/blue.

Exam reasonings: More rods on that part of retina than cones. Light rays converge (meet) at side of retina, not fovea.

Accomodation (Vision lab) (3)

Movement of lens with help of smooth muscle.

Near objects: objects get rounder, light rays converge (meet) on retina.

Far objects: lens get flatter.

Iris Photo

Cornea Photo

Pupil Photo

Aqueous Humor Photo

Lens photo

Vitreous humor photo

Optic disc photo

Optic nerve photo

Fovea photo

Retina photo

Sclera photo

Choroid photo

Fields of view

Optic Tract image

Optic nerve image

Eyes image

Retina image (vision pathway)

Optic chiasm image

Thalamus image

Occipital lobe image

Refracted light image comes to retina _____ an then is processed in occipital lobe as ________.

• Upside down

• Right side up

Conjunctiva function

Lubricates the eye

Emmetropia aka

Normal Vision

Emmetropia: Distant images: ______, Nearby Images:_____

• In focus

• In focus

Emmetropia image focuses ____ retina

on retina

Emmetropia eye shape

Normal eye shape

Emmetropia Corrective Lens Type

None

Hyperopia aka

Farsightedness

Hyperopia: Distant images: ____, Nearby Images: ____

• Focused

• Blurry

Hyperopia Image focuses where

Behind retina

Hyperopia eye shape

Too short eye shape

Hyperopia Corrective Lens type

Converging concave

Myopia aka

Nearsightedness

Myopia: Distant images: ____, Nearby images:____

• Blurry

• In focus

Myopia image focuses where

In front of retina

Myopia eye shape

Eye shape = too long

Myopia corrective lens type

Diverging concave

Visual Acuity

Amount of detail a person can see.

Astigmatism Issue

Irregular curvature of cornea or lens

Astigmatism & Cataracts vision are both

BLURRY

Cataracts issue

A cloudy lens

Conjunctivitis aka

Pink eye

Conjunctivitis Issue

Inflammation of the conjunctiva due to an infection.

Conjunctivitis Vision

N/A (Not affected)

Glaucoma issue

Posterior eye pressure from fluids which causes damage to the optic nerve

Glaucoma vision

Blurry, loss of peripheral

Macular Degeneration issue

Center of retina deteriorates or blood vessels leak under retina.

Macular Degeneration Vision

Loss of center vision

Retinal Detachment Issue

Innermost layer (retina) pulls away from the intermediate (choroid) layer.

Retinal Detachment Vision (4)

• Major dark floaters

• Flashing lights

• Corner of vision starts to disappear

• Blindness

Glaucoma image

Macular Degeneration image

Retinal detachment image

Cows have _________ which allows for night vision while humans do NOT

Tapetum lucidium

• Cow Layers (4)

1. Retina

2. Tapetum Lucidium

3. Choroid

4. Sclera