The Sense of Sight

The Senses

The Eyes

Multiple Select

Which of the following is a special sense?

• sight

• hearing

• balance

• taste

• smell

The Senses

​Special Senses

Sight, Smell, Hearing, Taste, and Balance are special senses

They are different to General Senses which are scattered throughout different regions of the body...for example: sensation of heat, cold, pain, nausea, hunger,thirst, and pressure (touch)

Our eyes are very similar to a camera...light rays enter the pupil and through a transparent lens where they are focused on the retina. The shutter is the iris allowing just the right amount of light in...the comparisons are endless!

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​Sight

Make sure you can label the eye!

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​The Eye

Hotspot

Label the following: Lens

Hotspot

Label the following: Pupil

Hotspot

Label the following: Retina

Multiple Choice

How many cells are located in the retina that turn what we see into electrical signals?

• 130 million

• 130 trillion

• 130 thousand

• Too many to count

External Structures of the Eye

​Orbit = cone shaped cavity formed by the skull

Eyeball - globe of the eye
Eyelid - one of two movable protective folds that cover the eye
Conjunctiva - transparent mucous membrane that covers inside of the eyelids
Lacrimal Apparatus - Involved in secretion and production of tears
Lacrimal Gland - Secretes Tears

Internal Structures of the Eye

​Vitreous Humor - (comedian of the eye) maintains the shape and refracts light

Sclera - white, tough, fibrous connective tissue that forms the outermost layer of the eye
Choroid - spongy membrane of blood vessels beginning at iris and working around the eye
Retina - Innermost membrane of the eye...contains rods and cones
Cornea - Transparent layer over the anterior of the eye
Iris - Colored ring of tissue that contracts to change the size of pupil.

Internal parts continued...

​Pupil - round opening in the iris that allows light rays to enter

Lens - clear, hard disk in the internal eye.
Ciliary Muscle - smooth muscle that alters the lens of the eye
Accomodation - change in size of the pupil and lens curvature to allow for proper focus on retina.

Farsightedness - occurs when the eye cannot focus on nearby objects.

Usually happens because the eyeball is too short, focal point the lens is beyond the retina

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Hyperopia

Nearsightedness - cause objects at a distance to be blurred.
Eyeball is too long and focal point of lens falls infront of retina.

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​Myopia

​Lazy Eye - poor vision in one eye because of dominance of the other

​​Amblyopia

Brain percieves images as two not one which creates...you guessed it...double double vision vision

​​Diplopia

​Degeneration of the retina which causes difficulty seeing at night...often caused by a Vitamin A deficiency.

​​Nyctalopia

Multiple Choice

____________ is a condition in which the eye can't focus on nearby objects.

• Myopia

• Diplopia

• Hyperopia

• Bifoculopia

Ishihara Charts

To test if you have colorblindness...

Multiple Choice

What number if any do you see?

• 15

• 45

• 18

• there is no number

Most people have a dominant eye...Which is yours? (Do Activity)

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​Dominant Eye

Poll

Which was your dominant eye?

• Left

• Right

Multiple Choice

What is the test used to determine if you are colorblind?

• Snellen

• Ishihara

• Mitsubishi

• Kawasaki

Multiple Choice

What does someone possibly have if they have trouble seeing at night?

• Nyctolopia

• Myopia

• Hyperopia

• Diplopia

Multiple Choice

What are located in the center of the eye and pick up bright light and colors?

• Rods

• Cones

• Stirrups

• Beams

Multiple Choice

The opening through which light passes into the eye..

• Cornea

• Iris

• Pupil

• Lens

Multiple Choice

Outermost layer of the eye that protects, maintains shape, and gives it its white appearance.

• Choroid

• Lacrimal Apparatus

• Sclera

• Lens

Multiple Choice

What is located in the orbit?

• Cochlea

• Lacrimal Apparatus

• Eyeball

• Accomodation

  Antagonist