The Senses

What are senses?

• response to the environment• received information from the environment

The sense of touch

• skin• receptors (specialized sensory structures)• Each receptor receives just one type of

stimulus (ex: touch, pressure, pain).

The sense of taste

• tongue• results from chemical

stimulation• taste buds• needs saliva and the

sense of smell

The sense of smell

• nose• also results from

chemical stimulation

The sense of hearing and balance

• ear• three parts: external, middle and inner

External ear

• Ear flap• External auditory canal

Middle ear

• Eustachian tube• Three tiny bones

– malleus (hammer)– incus (anvil)– stapes (stirrup)

• Oval window– Between the middle and

inner ear

Inner ear

Cochlea• Filled with liquid• Nerve endings that receive

“sound”

Auditory nerve• Picks up the “sound” and

sends it to the brain

The sense of sight

• eye• uses lenses• Protected by cornea• iris – smooth muscles that regulate opening

and closing (colored structure)– pupil (aperture) f/8.3, f/2.1

The sense of sight

• retina – light rays are focused– rods – photosensitive, but not color (night vision)– cones (color vision)

The sense of sight