K.C.S.E Biology Q & A - MODEL 2007PP2QN07
Describe the structure and functions of the various parts of the human ear
The ear is an organ involved in perceiving sound and maintaining body balance and posture. It is made of the following sections
Pinna – That is funnel shaped structure made of skin and cartilage. It receives sound waves and directs them to the ear tube.
External/auditory meatus – That is a canal lined with air and wax. It allows passage of sound waves to the middle ear. The hairs and wax trap dust particles that enter the ear.
Tympanic membrane – That is a thin flexible sheet-like structure receives sound waves and pass the vibration to the ossicles.
Middle ear that is composed of Tiny bones known as ossicles – They are anvil and incus. They amplify vibration from the tympanic membrane.
Eustachian tube – That connects the ear to the nasal cavity. It balances pressure on both sides of the tympanic membrane.
Oral window – That is a thin flexible membrane that opens into the inner ear. it receives vibrations from the ossicles and passes them to the inner ear.
Inner ear that is compost of;
Vestibular apparatus- That are the semicircular canals, utricles and saccules. They help in maintenance of body balance and posture.
Cochlea – That is a coiled structure that has sensory cells for hearing. It connected to the auditory nerve that is involved in transmission of sounds to the brain