Chapter 21

Chemicals called \(\quad\) are involved in the transmission of impulses at chemical synapse. (a) Neurohormones (b) Neurotransmitters (c) Receptors (d) Interferon

Which element ion helps in releasing Ach at synaptic cleft? (a) \(\mathrm{Na}^{+}\) (b) \(\mathrm{K}^{+}\) (c) \(\mathrm{Ca}^{+2}\) (d) \(\mathrm{PO}_{4}^{3-}\)

The new potential developed on post-synaptic membrane is (a) Excitatory always (b) Inhibitory always (c) May be excitatory or inhibitory (d) Neither excitatory nor inhibitory

Reflex action (a) Occurs involuntarily (b) Requires the involvement of CNS (c) Protective (d) All of these

Smallest reflex consists of (a) Afferent neuron (Receptor) (b) Efferent neuron (effector or excitor) (c) Both (a) and (b) (d) None of these

In reflex action, the reflex arc is formed by (a) Muscle, receptor, brain (b) Brain, spinal cord, muscle (c) Receptor, spinal cord, muscle (d) Receptor, muscle, spinal cord

Which of the following are due to reflex action? (a) Vomiting (b) Sneezing (c) Coughing (d) All of these

Which of the following are example of reflexes? (a) Knee-jerk reflex (b) Corneal reflex (c) Papillary reflex (d) All of these

The site for processing of vision, hearing, speech, memory, intelligence, emotions and thoughts is (a) Brain (b) Hear (c) Lungs (d) Kidney

Eyes are located in (a) Eye orbits (b) Depression in sphenoid bone (c) Both (a) and (b) (d) None of these

Choroid is blue due to (a) Lack of \(\mathrm{O}_{2}\), in tissues (b) Due to pigment (c) Excess of blood vessels (d) None of these

Choroid thickens anteriorly to form (a) Iris (b) Ciliary body (c) Suspensory ligaments (d) None of these

The diameter of pupil is regulated by (a) Lens (b) Ciliary muscles (c) Muscles of iris (d) All of these

Cells located in retina are (a) Photoreceptor cells (b) Bipolar cell (c) Ganglion cells (d) All of these

Layers in the wall of eyeballs from inside outwards are (a) Retina, choroid, sclerotic (b) Sclerotic, choroid, retina (c) Choroid, retina, sclerotic (d) Choroid, sclerotic, retina

Which layer of an eyeball wall contains abundant blood vessels? (a) Lens (b) Retina (c) Choroid (d) Sclerotic

Iris is a part of (a) Choroid only (b) Retina only (c) Sclera and choroid (d) Choroid and retina

The size of aperture of the pupil of one eye is controlled by (a) Iris (b) Retina (c) Cornea (d) Conjunctiva

Eye lens of a man is (a) Biconcave (b) Biconvex (c) Concave (d) Convex

Cornea is a transparent part of (a) Choroid (b) Sclera (c) Conjunctiva (d) Retina

The second layer of the eyeball is called (a) Choroid (b) Retina (c) Cornea (d) Sclera

The iris of the eye is an extension of (a) Cornea (b) Sclerotic (c) Retina (d) Choroid

The suspensory ligament (Zonule of Zinn) is a part of (a) Tongue (b) Brain (c) Heart (d) Eye

The choroid layer is thin over the of the eye ball (a) Anterior two-third (b) Posterior two-third (c) Lateral two-third (d) Posterior one-third

Find out the incorrect statement: (a) Lens is a transparent and crystalline structure. (b) Iris is pigmented and opaque layer. (c) The aperture surrounded by iris is called pupil. (d) Twilight vision is the function of cones.

Aqueous humor is present (a) In front of the retina (b) In front of cornea (c) Behind the conjunctiva (d) In front of lens

Retinal cells involved in colour vision are (a) Cones (b) Rods (c) Neurons (d) Neuroglial cells

Which of the following is not a basic colour in trichromatic vision? (a) Red (b) Yellow (c) Green (d) Blue

Which of the following passes from lens to blindspot? (a) Eustachian canal (b) Canal of Schlemm (c) Hyaloid canal (d) Semicircular canal

Colour vision in man is (a) Trichromatic (b) Bichromatic (c) Monochromatic (d) Achromatic

Quantum of light entering the eye through the pupil is dependent on (a) Ciliary body (b) Lens (c) Retina (d) Iris

Rhodopsin is a constituent of (a) Choroid (b) Sclera (c) Cornea (d) None

In nocturnal birds, the retina mostly contains (a) Cones (b) Rods (c) Both in equal numbers (d) None of these

Macula lutea is located (a) In the middle of retina (b) Below lens (c) Below pupil (d) At posterior polylateral to blind spot

Photopic vision is associated with (a) Rods (b) Cones (c) Both (a) and (b) (d) None of these

Retina is the most sensitive at (a) Optic disc (b) Periphery (c) Macula lutea (d) Fovea centralis

The aperture controlling light passage in the eye is (a) Pupil (b) Sclerotic (c) Blindspot (d) Iris

The space between cornea and lens is (a) Aqueous chamber (b) Vitreous chamber (c) Canal of Schlemm (d) Fovea centralis

Cones are sensitive to (a) Dim light only (b) Bright light only (c) Both dim and bright light (d) None of these

Colour is perceived by (a) Rods in retina (b) Cones in retina (c) Corneal-lens complex (d) Lens

Area of the most acute vision in the eye where sharp and bright image formed is (a) Yellow spot (b) Blindspot (c) Pupil (d) Lens

An area of the retina which does not have rods or cones are (a) Red spot (b) Blue spot (c) Blind spot (d) Black spot

Vitamin A combines with a protein in the retina to produce (a) Glaucoma (b) Night blindness (c) Rhodopsin (d) Colour blindness

The fovea is a portion of the (a) Thick-out, sclera (b) Thin-out, choroid (c) Thin-out, retina (d) Thick-out, retina

When all three types of cones are stimulated equally, a sensation of light is produced? (a) Black (b) White (c) Blue (d) Green

Select the incorrect matching: Part (a) Optic nerve (b) Cones (c) Cornea and lens (d) Pupil Function Carry impulse to visual cortex Colour vision Focusing of light on retina Generate action potential

Vitreous chamber is filled with (a) Transparent sol called vitreous humour (b) Transparent gel called vitreous humour (c) Opaque sol called vitreous humour (d) Opaque gel called vitreous humour

Select the incorrect statement from the following: (a) Rhodopsin is also known as visual purple. (b) Rods contain a purplish-red protein, which in turn contains the derivative of Vitamin \(\mathrm{A}\). (c) In human eye three type of cones are present. (d) At fovea of retina, the resolution (visual acuity) is minimum.

The location at which Optic nerve leaves the eye balls is (a) Slightly below the posterior pole of eye ball (b) Slightly above the posterior pole of eye ball (c) Anterior pole of eye ball (d) Macula lutea

Arrange the following steps of mechanism of vision in order. (1) Light induces dissociation of the retinal from opsin. (2) Change in the structure of opsin. (3) Change in membrane permeability. (4) Potential differences are generated in photoreceptor cells. (5) Generation of AP is ganglion cell through bipolar cells. (6) AP is transmitted via optic nerve to visual cortex. (7) At visual cortex, nerve impulses are analysed and the image formed on retina is recognized based on the earlier memory and experience. (8) Focusing of visible light on retina. (a) \(8,1,2,3,4,5,6,7\) (b) \(8,1,7,2,6,3,5,4\) (c) \(1,2,3,4,5,6,7,8\) (d) \(8,7,6,5,4,3,2,1\)