Vision

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Vision Objectives

List the five “traditional” senses and provide examples of additional senses.
Identify eye structures and describe their basic functions.
Describe perception, including the sensory receptors and role of the brain.

Senses are the way we collect data to form a perception, or idea, of the world around us.

From your background knowledge, list five human senses.

“Traditional” Senses

These are the senses most people know.

Vision

Rod and cone cells in human eyes send information on shape, depth, movement, and color to the brain.

Audition (hearing)

Hair cells in human ears collect information on sound amplitude and frequency.

Taste

Taste buds scattered on the tongue detect at least five tastes in humans: sweet, sour, salty, bitter, and umami (“savory”).

Olfaction (smell)

Ciliated receptor cells in the human nasal cavity can detect thousands of different odors.

Touch

Skin receptor cells can detect pain, heat, cold, light touch, and heavy pressure.

But wait...

We actually have more than these five senses.

The “traditional” five senses are generated by organs largely dedicated to sensory reception (eyes, ears, nose, tongue, skin).

But there are other senses created by smaller parts of an organ, and/or by multiple organs.

Additional Senses

These senses do not have dedicated organs (like the eyes or ears), and their mechanisms are not typically well understood.

Balance

Receptors in the skeletal muscles, ears, and eyes play a role in human balance.

Proprioreception

This is awareness of where parts of the body are located: it enables you to touch your nose with closed eyes.

Pain

Receptors in the skin, joints, bones, and soft organs send pain signals when tissue damage has occurred. This is a wider sense that simple pain reception by nerve endings in the skin.

Hunger

Multiple parts of the brain are responsible for the feeling of hunger that assists in energy management.

Chronoreception (passage of time)

Awareness of the passage of time is impacted by multiple brain structures and includes short term time and daily circadian rhythms.

Assorted Internal Senses

At least eight additional senses include detecting a full bladder, thirst, and more.

In this section we are focusing in on one of the most studied senses: vision.

The next section compares and contrasts hearing, taste, and smell.

Here we have a model walk-though of eye anatomy.

A different view of basic eye structures and functions.

Vision is a series of steps involving the eye and brain.

Changes to eye structures can result in visual impairment.

We’ll cover additional visual disorders in the context of aging in Guide 7b.

Retina

The retina is the “business end” of the eye because it contains the rods and cones. This model shows other supporting tissue layers in the retina.

An amazing slide clearly shows the layers of tissues that make up the retina.

Color vision can vary due to differences in the _____ receptor cells within the retina.

Perception is a combination of stimulus from the receptor cells and interpretation by neurons in the brain. In the case of vision, the receptor cells are _____ and _____. The part of the cerebral cortex that primarily processes visual information is the ____ lobe.

The next section provides additional examples of perception while comparing other senses.

Check your knowledge. Can you:

list the five “traditional” senses and provide examples of additional senses?
identify eye structures and describe their basic functions?
describe perception, including the sensory receptors and role of the brain?