Describe the structure and functions of the mammalian ear for hearing.

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  • The ear performs two major functions, Hearing; and detecting changes in the position of the body;
  • the ear is divided into three sections the outer ear; middle ear; the inner ear;
  • Pinna collects and concentrates sound waves into the external auditory meatus; which conveys them to the eardrum/tympanic membrane
  • the external auditory meatus has hairs and wax; to trap solid particles/dust that would damage the ear drum;
  • The ear drum vibrates as the sound waves strike it; the sound waves are converted into sound vibrations; which are then transmitted to the ear ossicles (malleus, incus and stapes) while being amplified; the stapes pass the vibrations to the oval window which vibrates; passing the vibrations to the perilymph of inner ear;
  • from the perilymph the vibrations are passed up to the reissner’s membrane; which passes them to the endolymph of he middle canal of the cochlea;
  • the Basilar and tectorial membrane pick up the vibration from endolymph; and transmit them to the organ of corti; the sensory hair cells; in the organ of corti are thus stimulated by the vibration, hence they trigger off nerve impulses; which are transmitted to the brain via the auditory nerve fibre; for interpretation; the organ of corti discriminates sound according to their frequencies; the intensity of stimulation of sensory hair cells determines the pitch/loudness of sound.
 ( Max (20 mks)

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