1. The Ear
Biology 30

2. The Ear – label your diagram

4. Outer Ear:
Pinna: The external flap of the ear. Funnels sound into the auditory canal.
Auditory Canal:
Directs sound toward the tympanic membrane towards the ear drum
Has modified sweat glands (Ceruminous Glands) that secretes wax to protect from foreign material (keeps ear moist; trap dirt, debris, etc)

6. Middle Ear: Tympanic Membrane Ossicles Eustachian Tube
Turns sound waves into a vibration
also called the “ear drum”
Ossicles
Three ossicles: Malleus (Hammer), Incus (Anvil), Stapes (Stirrup)
Amplifies and transfers the vibrations from the tympanic membrane to the oval window
Eustachian Tube
Connects middle ear to the back of the throat (pharynx)
Equalizes air pressure in the middle ear and allows proper movement of the tympanic membrane

8. Inner Ear - Hearing:
Cochlea - coiled structure of the inner ear, responds to various sound waves and converts them to nerve impulses
Oval Window – receives vibrations from the ossicles (specifically stapes)
Round Window – absorbs the sound wave
Organ of Corti – primary sound receptor in the cochlea (hair cells in cochlea and neurons they’re attached to)
Nerve impulse travels from the auditory nerve to the temporal lobe and are interpreted as sound.

10. Organ of Corti
Is a ridge of cells that runs along the basilar membrane. The top of the organ of Corti meets the tectorial membrane

11. Hearing Animation
30/student/protect/webactivities/unit30Ach14.html#14.2
Username: nelsonbio_student
Password: nelsonbio_onlinelearning

12. Inner Ear – Balance: Semicircular Canals Vestibule
Arranged in all three dimensions of space
Base of each canal has hair cells with cilia
Provide a sense of balance (dynamic balance – 3D motion)
Vestibule
A chamber between the semicircular canals and cochlea
Contain two membrane sacs: Utricle and Saccule
static balance, when you move your head
Both contain hair cells with cilia protruding into a gelatinous material that has otoliths (calcium carbonate particles)

16. Balance – Semicircular Canal
Fluid inside the canals flows in the direction of motion.
Small jelly-hairs bend in the direction of the fluid flow
Nerves fire and the brain interprets motion & responds for balance

18. Balance Dynamic Equilibrium – required when the body is moving
Fluid in the semicircular canals causes bending of the hair cells which generates a nerve impulse which travel to the temporal lobe of the brain
Continuous movement causes motion sickness
Static Equilibrium – required when the head or body move horizontally or vertically
Otoliths in vestibule of utricle and saccule are displace by gravity
The otoliths come in contact with the hair cells bending them which generates a nerve impulse which travels to the temporal lobe of the brain

20. Hearing Summary: Sound waves are vibrating molecules
Sound waves cause the tympanic membrane to vibrate slightly
Malleusincus stapes relay vibration to the oval window with a 20-fold increase in pressure
Vibration at oval window are converted into compression waves of the inner ear
The compression wave travels through the vestibular canal and then the tympanic canal
This causes the basilar membrane in the cochlear canal to move up and down also moving the Organ of Corti
Cilia in the Organ of Corti rub against the tectorial membrane initiating a nerve impulse
The vibration is absorbed by the round window at the end of the cochlea
The nerve impulse travels along the auditory nerve to the temporal lobe
Long wide hair responds to low pitch sound and short narrow hair respond to high pitch sound

21. STS – Hearing technology
Hearing aids
Bed vibrator: clock & fire alarms
TTY Phone
Closed caption TV
Pager/Vibrator: doorbell, contacts