Explain how structures of the human ear are adapted to their functions. (20 marks)

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  • The pinna;- is funnel shaped to trap sound waves; cartilaginous to maintain the funnel shape; collects and directs sound waves into the external auditory meatus ear;
  • The external auditory canal; - a tube connected to the pinna that directs sound waves from the pinna to the eardrum lining the auditory canal; has hair that trap foreign particles;
  • The canal contains wax-secreting cells; and hair which traps dust particles; and pathogenic bacteria hence prevent them from getting into the ear;
  • The eardrum; - has a thin tough membrane; that easily vibrates when hit by sound waves; transferring them into vibrations.
  • The ear ossiscles; - they act like a layer and they easily move forward and backward to amplify sound vibrations that hit them;
  • The suspensory ligaments; - suspends the ear ossicles and prevents excessive vibration that would otherwise damage the inner parts of the ear;
  • The eustachian tube - it connects the middle ear with the pharynx; and it equalises air pressure between the middle and the outer ear so as to prevent distortion of the eardrum;
  • The oval window;- has thin membrane that transmits sound vibrations into the endolymph;
  • The cochlea;- highly coiled to occupy a small area but to accommodate a large number
  • of sensory cells;
  • The perilymph and endolymph; - these are fluids that absorb mechanical shock; hence protect the delicate\parts in the inner ear; They also transmit vibrations to the inner parts of the ear;
  • The sensory cells; - when stimulated, they generate nerve impulses; which are transmitted by the auditory nerve to the brain;
  • The semi-circular canals; - these are tubular cavities that maintains body balance and posture; they contain special cells that are sensitive to changes in gravity;
TOTAL 29 MAX 20
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