Senses Detecting the World

Senses Objectives

List the five “traditional” senses and provide examples of additional senses.
Identify eye structures and describe their basic functions, including their role in vision and perception.
Describe the sensory receptors, potential types of information sent to the brain, and common misconceptions for hearing (audition), taste (gustation), and smell (olfaction).

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.

We will focus first on one of the most studied senses: vision.

We are taking 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.

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.

Our senses often work together to create a richer perception of the world.

This is one of a few human biology videos we shot last summer.

Senses connect us to our external and internal environment, analogous to a car’s sensors telling it when something is too close or oil levels are low.

A classic book for understanding the significance of sensory input is Hellen Keller’s autobiography “The Story of My Life,” first published in 1903 and written while the author was still in college.

Now we will compare and contrast three different senses: hearing (audition), taste, and smell (olfaction).

Common misconceptions about human senses

Ear Repair

Although some parts of the body heal quickly with healthy cells dividing to replace dead or injured cells, some cells like the receptor cells of the ears rarely divide. This means damage by a single large vibration (sound) can lead to permanent hearing loss.

Taste Map

Many older textbooks show a map of taste buds on the tongue with zones of clustered taste receptors. The tongue actually has assorted taste receptors, not specific regions of taste.

Best Sense?

When asked about their weakest sense, many people say their sense of smell. Most people can actually detect thousands of different scents, like the smell of different apple varieties, but the brain has to be taught to identify them.

Hearing (Audition)

The ear is analogous to a funnel directing vibrations to the sensory cells located in the cochlea of the inner ear.

The ears have two important sensory roles: hearing and balance.

You may have heard that when you hold a conch or other large shell to your ear, you can hear the ocean. You are actually hearing ambient noise around you amplified in the shell. It acts like a small resonating chamber.

Taste (Gustation)

This model shows the little ridges on the tongue (papillae) that have valleys lined with taste buds.

A magnification of tongue tissue clearly shows the papillae and taste buds.

Smell (Olfaction)

Ciliated receptor cells in the nasal epithelium at the roof of the nasal cavity bind to odor molecules, sending signals through an olfactory nerve to the brain.

Dogs have a better sense of smell than humans do, and its not just because they have large moist noses that are often close to the ground. Dogs, and their ancestors the wolves, have more ciliated receptor cells in their olfactory epithelium.

This scent memory demo demonstrates the hedonic scale you will be using in the next journal assignment.

Start this Guide’s second journal assignment here

Journal Page #10: Sensory Experience

For this journal assignment you are trying a novel (new) sensory experience and describing the experience on the hedonic scale.

First, select a sensation that you have not experienced before. It could be a new combination of tastes, a new scent, trying a type of music, making a new mix of textures, etc.

The journal page you are turning in includes the following three components:

An explanation of why you selected this particular sensory experience.
A description of the experience.
A rating of your novel sensory experience using the hedonic scale.

You can submit text, text and photos, and/or a video.

Note: Exercise safety in your selection and execution of this media piece. Also, keep the description appropriate for a wide audience. In other words, don’t shock the graders.

This is the end of Guide 5’s content. After you check your knowledge over the material, proceed to the product page.

Check your knowledge. Can you:

list the five “traditional” senses and provide examples of additional senses?
identify eye structures and describe their basic functions, including their role in vision and perception?
describe the sensory receptors, potential types of information sent to the brain, and common misconceptions for hearing (audition), taste (gustation), and smell (olfaction)?

Go back to the Brain Page

Guide 5 Product Page

Coordination Guide Contents

Complete all four of these sections before taking the quiz and submitting your two journal pages.