21
Sense of Hearing Ear -important for hearing and equilibrium -made of the outer, inner, and middle ear

Sense of Hearing Ear -important for hearing and equilibrium -made of the outer, inner, and middle ear

Embed Size (px)

Citation preview

Page 1: Sense of Hearing Ear -important for hearing and equilibrium -made of the outer, inner, and middle ear

Sense of Hearing• Ear

-important for hearing and equilibrium-made of the outer, inner, and middle ear

Page 2: Sense of Hearing Ear -important for hearing and equilibrium -made of the outer, inner, and middle ear

Outer Ear• Pinna (auricle)-surrounds entrance to the external auditory

canal

– Made of elastic cartilage

– Helps collect sound waves

• External Auditory Canal

– Has ceruminous glands that create ear wax

– Wax helps to slow the growth of microorganisms

– Small hairs prevent the entry of objects and insects

• Eardrum (tympanic membrane)

– Thin membrane that separates external from middle

– Vibrates in response to the change in pressure

– Begin of middle ear

Page 3: Sense of Hearing Ear -important for hearing and equilibrium -made of the outer, inner, and middle ear

CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Page 4: Sense of Hearing Ear -important for hearing and equilibrium -made of the outer, inner, and middle ear

Middle Ear Job-send vibrations onto inner ear

• Made of the tympanic cavity (air filled)• Auditory ossicles: 3 small bones

– Malleus, incus, and stapes (smallest bone in body)– Bridge between outer and inner ear– Malleus is attached to ear drum and passes on

vibration to incus and then to stapes• Stapes’ vibrations will cause inner ear fluid to

move– Increase or amplify the vibrations

• Gating (decrease loudness of sound) and impedance matching (gathering of weak sounds and concentrate it on an area)

Page 5: Sense of Hearing Ear -important for hearing and equilibrium -made of the outer, inner, and middle ear

CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display.

anvil

hammer

Stirrup

Page 6: Sense of Hearing Ear -important for hearing and equilibrium -made of the outer, inner, and middle ear
Page 7: Sense of Hearing Ear -important for hearing and equilibrium -made of the outer, inner, and middle ear

Middle Ear-Auditory Tube (eustachian tube)

-connects to nasopharynx-regulates pressure on both sides of the

ear drum which is important for normal hearing

-allows for drainage of mucus from the middle ear into the throat

CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Page 8: Sense of Hearing Ear -important for hearing and equilibrium -made of the outer, inner, and middle ear

Middle or Outer Ear Issues-middle ear infections (acute otitis media)-

caused by mucous infections from auditory tube moving into the middle ear/presence of fluid in the middle ear

-ears popping-eardrum moves back to the original position after the change in pressure/auditory tube fixing pressure

-ear tubes-fluid forms behind eardrum and help to rid of the fluid

-swimmer’s ear-infection in the ear canal-water build up causes bacteria or fungus to grow

Page 9: Sense of Hearing Ear -important for hearing and equilibrium -made of the outer, inner, and middle ear

Inner Ear-fluid filled• Sense of equilibrium and hearing

receptors in this region• Membranous labyrinth-collection of

tubes and chambers– Fluid filled-endolymph (protect receptors)

• Osseous labyrinth-dense bone that surrounds and protects membranous labyrinth

– Contains fluid called perilymph

CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Page 10: Sense of Hearing Ear -important for hearing and equilibrium -made of the outer, inner, and middle ear

CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Page 11: Sense of Hearing Ear -important for hearing and equilibrium -made of the outer, inner, and middle ear

Inside bony labyrinth• vestibule-receptors here provide sensations of

gravity and change of speed/direction• Semicircular canals-respond to rotational

movements (function in equilibrium)• Cochlea-filled with fluid; provide sense of hearing

– Covered with tiny hairs on the basilar membrane– Movement creates nerve signals that the brain

(temporal lobe) interprets as signals– Round window (membrane) is attached to this– Has organ of corti that has hearing receptors

CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Page 12: Sense of Hearing Ear -important for hearing and equilibrium -made of the outer, inner, and middle ear

How do we hear? Need to write• Organ of Corti has hearing receptors that are stimulated

by the fluid vibrating (in cochlea)

• External acoustic meatus sends sound to ear drum, which vibates

• ossicles pick up vibraiton (incus, malleus, etc)

• Oval window transmits vibrations to vestibular membrane

• Travels to cochlea (has endolymph)

• Different vibrations in endolymph stimulate receptor cells (organ of corti)

• Depolarize receptor cell; release nt; signal to temporal lobe

Page 13: Sense of Hearing Ear -important for hearing and equilibrium -made of the outer, inner, and middle ear

CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Page 14: Sense of Hearing Ear -important for hearing and equilibrium -made of the outer, inner, and middle ear

Sense of Equilibrium

Two types of equilibrium• The organs of static equilibrium help to

maintain the position of the head when the head and body are still.

• The organs of dynamic equilibrium help to maintain balance when the head and body suddenly move and rotate.

CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Page 15: Sense of Hearing Ear -important for hearing and equilibrium -made of the outer, inner, and middle ear

Static Equilibrium-body position at rest

• Vestibule is in charge of static equilibrium– Made of chambers called utricle and saccule

• Chambers have macula– Macula has many hair cells that are sensory receptors

– Gel-like substance that hair cells project into

– Otoliths-calcium carbonate around gel substance

• Bend head to side-stimulates hair cells• Hairs bend and tilt into gel substance cause action

potential to be sent • Signal sent to brain to tell what is going on

Page 16: Sense of Hearing Ear -important for hearing and equilibrium -made of the outer, inner, and middle ear
Page 17: Sense of Hearing Ear -important for hearing and equilibrium -made of the outer, inner, and middle ear

CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Pick up head position

Static equilibrium

Page 18: Sense of Hearing Ear -important for hearing and equilibrium -made of the outer, inner, and middle ear

Dynamic Equilibrium-motion balance

• 3 semicircular canals of labyrinth are the important organs

• Ampulla-swelling in perilymph of bony labyrinth– Contains sensory organs called crista ampullaris

• Have hair cells and support cells• Hairs extend into gel mass called capula

– Hairs move opposite of body movement• Send signal to brain (cerebellum)

Page 19: Sense of Hearing Ear -important for hearing and equilibrium -made of the outer, inner, and middle ear

CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Dynamic Equilibrium

Page 20: Sense of Hearing Ear -important for hearing and equilibrium -made of the outer, inner, and middle ear
Page 21: Sense of Hearing Ear -important for hearing and equilibrium -made of the outer, inner, and middle ear

Deafness• Conductive deafness

– Middle ear issues– Block the normal transfer of vibrations from the

tympanum to the oval window– Caused by scarring or perforation of tympanum or

ossicle immobilization

• Nerve deafness– Cochlea issues– Receptors do not respond or reach their destinations