Describe the structure and functions of the various parts of the mammalian ear.

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  • Pinna; is wide/funnel-shaped to collect/gather sound waves; and direct them to the auditory canal into the ear; 
  • External auditory canal cells produce/secrete wax; to trap dust particles/solid/micro-organisms that can damage eardrum;
  •  Eardrum/tympanic membrane is thin and light; to convert sound waves into vibrations; 
  • Ear ossicles/maleus, incus and stapes are of high density; to magnify/amplify sound waves;
  • Oval window is smaller than eardrum; to magnify the sound waves; and direct them to the inner ear; 
  •  Cochlea is long and coiled; to increase surface area; for attachment of receptor cells/sensory hairs; cochlea has many sensory hairs; which receive sound vibrations and generate impulses; Liquid or fluid/endolymph in cochlea; transmit sound vibrations; auditory nerve; transmit impulses to the brain for interpretation; 
  •  Eustachian tube; link the mouth and middle ear to equalise pressure; between middle and outer ear to prevent damage to delicate eardrum; 
  •  Round window; lose excess vibrations; to avoid continuous stimulation; 
  •  Semicircular canals; contain receptors for body balance and posture;  
Max. 20 mks
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