that are manufactured by the cell body of neuron and not axon.
These substances are discharged in to
the space between two neurons and propel the message on to the next neuron.
The neurotransmitters excite, inhibit or modify signals to the second neuron (post-synaptic neuron) by interacting with the receptors on its membrane.
2. D. Endorphin exhibits excitatory action,transmits pleasurable
sensation and inhibits pain transmission. The sources of endorphin are nerve terminals in the spine, brainstem, thalamus and hypothalamus. Another neurotransmitter having similar action is enkephalin. Gamma-aminobutyric acid (GABA) is inhibitory.
conveys muscle and nerve transmission.Dopamine also
is inhibitory, affects behavior and
fine movement. Serotonin is inhibitory, helps control mood and sleep. and inhibits pain
pathways.
3. B. Parietal lobe is predominantly sensory lobe.Contains the primary sensory cortex. Analyzes
sensory information and relays to the thalamus and other cortical areas. It is also responsible
for proprioception. Frontal lobe is the largest and controls abstract thought. concentration,
information storage or memory and motor function. Temporal lobe contains the auditory receptive
area and is the interpretive area. Occipital lobe is responsible for visual interpretation.
4, B. Cerebellum is largely responsible for coordination of movement. It also controls fine
movement, balance, position sense and integration of sensory input. Bfainstem consists
of midbrain, pons and medulla and contains cardiac, vasomotor and respiratory centers.
Thalamus is a relay station for all sensation except smell. Hypothalamus is the center for
temperature control, water metabolism, control of hormonal secretion, heart rate, peristalsis, and
appetite control, thirst and sleep-wake cycle.
5. D. The part of brain, which plays an essential role in
the process of memory is hippocampus
and is situated in the medial section of the temporal lobe. Frontal lobe primarily functions
in thinking, planning, tudgement and past memory. Occipital lobe is the center of vision.
Parietal lobe is mainly responsible for sensory functions.
6. B. The heat regulatory center is located in hypothalamus.
Thalamus channels all sensory
information except smell. Limbic system is the center for
emotional expression and feelings.
Medulla is the motor and sensory pathway between brain and spinal cord.
7. C. Cranial nerve IV or trochlear nerve is responsible
for extraocular eye movement.
Cranial nerve VIII. vestibulocochlear, is responsible for hearing, cranial nerve II. optic. is
responsible for vision and cranial nerve V or trigeminal nerve is responsible for chewing.
8. B. Vestibul0chlear nerve is responsible for hearing and
maintaining equilibrium or balance.
Trochlear nerve functions in eye movement
Trigeminal nerve is for somatic sensation of face
and chewing and vagus nerve is responsible for pharynx,
respiratory, cardiac and circulatory
reflexes.
9. A_ Cranial nerve ill, oculornotor, if damaged gives rise to ptosis or drooping eyelids.
Disorder
of cranial nerve V or trigerninal nerve is trigeminal neuralgia causes lace pain.
Disorder of the
cranial nerve VI. abducens will cause inability of the eye to move laterally outward.
Disorder of the cranial nerve VIII, vestibulocochlear is seen in Meniere's's syndrome.
10. D. Treatrnent of a chalazion is surgical removal of the
chronic lesion by incision and curettage
or injection of corticosteroids into the lesion
by not avoid climbing stairs.
an opthalmologist. Application of antibiotic ointment is ineffective.
Warm moist compresses
may cause spontaneous drainage in the early stage.
11. B. The graft taken for corneal transplantation
is from human cadaver eyes. Synthetic polymerarid graft
taken from pig or monkey are not used.
12. B. A cataract is opacity in the crystalline lense.
Patients with cataract usually complain of
decreased vision, abnormal color perception and glare,
which is worse at night. Loss of
peripheral vision is found in glaucoma.
Floaters in eye is a symptom of retinal detachment.
Seeing halos around light is also a symptom of glaucoma.
13. C. The visual defect, Le. farsightedness resulting from
the decrease in accommodative
ability of the eye in aged is presbyopia. Myopia is nearsightedness,
light focusses in front of
retina, occurs due to excessive refractive power of cornea or lens
or too long eyeball. Hyperopia
is farsightedness. light focusses behind the retina. results from
too short eyeball, or
inadequate refractive power of the lens or cornea.
Amblyopia is reduced vision in the affected eye.
may occur in children if their refractive error is not corrected.
14. C. The cause of presbyopia in individuals above the age of 40 years is reduced elasticity
of the lens. With aging the crystalline lens becomes larger firmer and less elastic. These
changes decrease the eye's accommodative ability and results in dificulty focussing near
objects. Presbyopia is not due to retinal degeneration, decreased corneal refractive
ability or opacity in crystalline lens.
15. A_ Presbyopia or farsightedness occurring in individual above
the age of AO years is corrected
by use of convex lens. Glasses far presbyopia are often
called reading glasses as they are
usually worn for close vision only. Concave lens is used for
correction of myopic vision. Both
convex and concave lenses maybe used when presbyopic
correction is combined with
correction of myopia. Refractive surgery is most commonly
employed in the correction of myopia.
16.A. A Phacoemulsification belng a sutureless surgery recovery
is early and refraction can be
done after 1-2 weeks of surgery. In conventional surgery where sutures
are used refraction for correction of residual refractive error is done
when eye is fully recovered and 2 weeks after
suture removal, i.e. usually 8 weeks. 4 weeks is too early and 12 weeks is too late for this
purpose.
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