Hearing• What is the stimulus for hearing?• Sound

• What is sound?• Vibrations of different wavelengths• Different wavelengths produce different pitches

• What media can sound waves travel through?• Gas, liquid, and solid

How do we hear?1. Sound waves are gathered by the outer ear2. Sound waves strike the eardrum, causing it to vibrate3. Vibrations pass from the eardrum to the hammer, anvil, and

stirrup in the middle ear4. Vibrations are send to the cochlea, which contains fluid and

hair cells5. The hair cells bend in response to vibrations, which sends an

electrical message to the auditory nerve6. The auditory nerve carries this message to the temporal lobe 7. Messages can be carried further to other areas of the brain in

order to compare sounds and make sense out of what was heard

Why do we sound different to ourselves?

When you talk, the sound waves travel through your jawbone and through your mouth as well as through the air in your ear

When you listen to yourself on tap, the sound waves only travel through the air in your ear

What are some affects of listening to loud noise?• Long exposure to sound above 80 decibels permanently damages hair

cells in the ear, causing hearing loss• Excessive noise causes high blood pressure, quicker heartbeats,

learning difficulties, and disturbed sleep patterns

Why is sound important?• Give three examples in which being able to hear sound is very

important. Identify the stimulus and response in each example.

Smelling• What is the stimulus for smell?• Chemicals in the air

• What are the seven basic odor types?• Floral• Mint• Camphor• Ethereal• Must• Pungent• Putrid

How do we smell?1. Chemicals in the air go through the nasal cavity and up to the top of the nose2. The top of the nose is covered with mucus, which dissolves the chemicals3. The top of the nose has multiple types of smell receptors4. Each receptor has a special shape that can only fit certain chemical molecules5. When a chemical molecule fits the receptor, the receptor sends a message to a neuron6. The neuron sends the message to the olfactory bulb (under the frontal lobe) and

then to the temporal lobe7. Messages can be carried further to other areas of the brain in order to compare smells

and make sense out of what was smelt

How does a cold affect your sense of smell?• Each sinus has lining that produces mucus that drains to the nose and

throat; when the lining gets infected or inflamed, mucus builds up because it is unable to drain, causing pain and pressure• When the lining is inflamed and infected, the chemicals do not fit the

receptors, so you cannot smell as easily

Why is smell important?• Give three examples in which being able to smell is very important.

Identify the stimulus and response in each example.

How are smell and taste related?• About 70% of what we taste comes from our sense of smell• Taste buds on our tongue allow us to detect bitter, salty, sweet, and

sour flavors• Odor molecules from food give us most of our taste sensation

How do we taste?1. Chemicals dissolve in saliva on our tongue, which

has taste buds covering it2. Taste buds contain receptors that respond to

either salty, sweet, sour, or bitter3. When chemical touches receptor, receptor sends

electric message to neuron4. Neuron sends message to the temporal lobe5. Messages can be carried further to other areas of

the brain in order to compare tastes and make sense out of what was tasted