Theory question 102
Sense Organs(a) Make a labelled diagram to show the internal structure of the mammalian ear
(b) Describe the mechanism of hearing in mammals
(c) State two ways of caring for the ear.
Show the model answer
(a) Labels: pinna, external auditory canal, tympanic membrane (eardrum), malleus, incus, stapes, oval window, round window, semicircular canals, cochlea, auditory nerve, Eustachian tube
(b) Pinna collects sound waves into the auditory canal; they make the eardrum vibrate
The ossicles (malleus, incus, stapes) pass on and amplify the vibrations to the oval window
Vibrations of the oval window set up waves in the perilymph and endolymph of the cochlea
Sensory hair cells in the organ of Corti are stimulated and send impulses along the auditory nerve to the brain, which interprets them as sound
(c) Any two: do not push sharp objects into the ear; clean the outer ear gently; avoid very loud noise; treat ear and throat infections promptly; do not slap the ear
Follow the sound from the pinna to the brain step by step.