Our Senses

Chapter 8.2

• It is TRUE that when you look at a rainbow, the wavelength of light determines the colors you see– Red wavelength is longer than orange &

continues to get shorter until violet which has the shortest wavelength

Light

• Electromagnetic energy– Described in

wavelengths– Not all light is visible to

humans– Wavelengths can be a

fraction of an inch to miles long (cosmic-radio)

The Eye• Similar to a camera• Amt. of light that enters

is determined by opening of the colored part of eye– Blk. area is pupil– Pupil size is sensitive to

our emotions• Light then encounters

the lens; adjusts to the distance of objects by changing its thickness– Squinting is people

adjusting their lenses

• The changed image is projected onto the retina– Like the film in camera; neurons that are

sensitive to light (photoreceptors) carries the input to the brain

– Information is relayed to visual area of brain• Blind Spot

– We all have one, area of eye where there are no photoreceptors

• Rods & Cones– Rods-sensitive to

brightness– Cones-provide color

vision• Adaptation

– May take time for eyes to adjust to a dark room

– Adaptation to bright light happens more quickly

• Visual Acuity– Sharpness of vision– Ability to see visual

details

Color Vision • People with normal color vision see any color in the spectrum of visible light

• When one color stimulates the cones, we perceive more colors

• Color Blindness; people who do not have normal color vision– Malfunction of cones

Hearing

• Hearing depends on the vibrations of the air (known as sound waves)– Once the sound waves

hit the ear, tiny hair cells move back & forth

– Hair cells then change sound vibrations into neuronal signals that go to the brain

• Loudness=amplitude (or height) of sound– Measured in decibels

• Normal range of hearing is from 0-140 decibels– Damage can be done

to your ear @ 110 decibels

• Look on website info.http://www.centerpointaudio.com/

Earbud-Safety.aspx

How we hear sound

• Watch the short video about how we hear:

Deafness

• 2 Types– Conduction; when

there is a hindrance of physical motion through the outer/middle ear OR damage to the bones

– Hearing aid can help

• Sensor neural– Damage to the

cochlea, the hair cells or auditory neurons

– Need a cochlear implant to help

Balance

• Sense of balance is regulated by the inner ear

• Overstimulation can cause dizziness & motion sickness

Smell & Taste

• Check back here!• We’ll be doing an

experiment over smell & taste on Tuesday