1. Inner Ear
Balance Mechanisms

2. Balance Mechanisms
Vestibule
Semicircular Canals

3. Static Equilibrium

4. Static Equilibrium associated with vestibule
receptors in chambers - saccule and utricle and contain maculae

5. Static Equilibrium Reports on body position in respect to gravity
Responds to linear acceleration

6. each maculae is a flat patch of epithelium with scattered supporting cells and receptor “hair” cells

7. hair cells are embedded in a jelly-like membrane that also contains tiny Ca crystals called otoliths (ear stones)

8. displacement activates receptors because hair cells move

11. Dynamic Equilibrium

12. Dynamic Equilibrium
monitored by the ampullae at base of the semicircular canals
evaluates the change in rate of movement

13. inside each is a crista ampullaris with hair cells in jelly covering - cupula
Semicircular canal
ampulla
hair cell

14. each canal orients in a different place so acceleration at all angles can be monitored

15. if constant rotation occurs, hairs will quit bending and bend the other way when we stop
bony labyrinth moves with body - fluid and gels move at various rates depending on different forces

18. Ear Disorders

19. Motion Sickness difficult to explain
probably due to sensory input mismatch caused by continuous stimulation of the semicircular canals
consists of nausea and weakness

22. Deafness or hearing loss can be:
Conduction
Outer ear or middle ear
Sensorineural
Inner ear

23. 1. Conduction
something interferes with vibrations or transmission of sound waves

24. Examples of causes:
ear wax build up
ruptured eardrum

25. Examples of causes:
otosclerosis - connective tissue grows over stapes and oval window

26. helped by hearing aid and surgery

28. 2. Sensorineural
Involves damage to the organ of Corti hair cells or nerve pathways

29. Examples of Causes:
Loud noise that pulls hair cells away from nerve endings

35. Examples of Causes:
Tumors

36. Cochlear implants convert sound to electrical stimuli delivered to the cochlear nerve