Intext Practice Questions
- Name the three ossicles and state their function.
- Why is organ of Corti said to be the organ of hearing?
- How does the ear help in maintaining static and dynamic equilibrium?
- How does tensor tympani muscle prevent damage to internal ear?
- With the help of a flow chart, explain the mechanism of hearing.
static equilibrium and linear acceleration
• maculae detect changes in the head (or body) with respect
to gravity (static equilibrium) and in the movement in one
direction (linear acceleration).
• With a change in the position of the body, the otoliths,
being heavier than the endolymph, press upon the
sensory hair of the maculae.
• This stimulates the sensory cells which initiates nerve
impulse in the fibres of the vestibular branch of auditory
nerve to the cerebellum for interpretation. cerebellum
then sends reflex signals for restoring static balance.
• The macula of utricle responds to vertical movements of
the head, and the macula of saccule responds to lateral
(sideways) movements of the head.EAr dEFECts
• Deafness - Deafness may be partial or complete and
may be caused by damage to the conduction system or
to the nerve fibres or receptor cells.
• Vertigo - It is a disabling sensation in which the
affected individual feels that either he himself or his
surroundings are in a state of constant movement. Itis most often a spinning sensation, but there may be
a feeling that the ground is tilting. It is a symptom of
disease either in the labyrinth of the inner ear or in the
vestibular nerve or its nuclei in the brainstem which are
involved in the sense of balance.
• Tinnitus - a ringing sensation in the ear caused
by irritative stimulation of either the inner ear or the
vestibulo- cochlear nerve. In this, the person hears
when there is no real sound. It is usually accompanied
by hearing loss.
• Otalgia - Ear pain.
• Otitis - Inflammation of ear.
• Otitis externa - Inflammation of the canal between
the ear drum and the external auditory meatus.
• Otitis media - This is an acute infection of the middle
ear caused mainly by bacteria and associated with
infection of the nose and throat. The symptoms of otitis
media are severe pain, fever and irritability.
• Meniere’s disease - It is due to an increased amount
of endolymph that enlarges the membranous labyrinth.
Its symptoms are spontaneous episodes of deafness,
roaring tinnitus (ringing), spinning or whirling vertigo
(dizziness).- Which part of the human ear plays no role in hearing as
such but is otherwise very much required?
(a) Eustachian tube (b) Organ of corti
(c) Vestibular apparatus (d) Ear ossicles - Which of the following statements is not correct about
choroid?
(a) It is the most vascular structure.
(b) It is darkly pigmented.
(c) It prevents internal reflection of light.
(d) It is the visual portion of retina.
3. arrange the following based upon the mechanism of
vision.
(1) absorption of visible wavelength of light by rods
and cones
(2) change in the permeability of photoreceptors cells
(3) Dissociation of retinal from opsin
(4) Generation of action potential in the ganglionic
cell
(a) 1, 2, 3, 4 (b) 1, 3, 2, 4
(c) 1, 4, 2, 3 (d) 1, 3, 4, 2