Effects of Acetylcholine, Pilocarpine, and Other Drugs on Cholinergic Receptors
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Questions and Answers

What is the refractive power of the cornea alone?

  • 22 diopters
  • 44 diopters (correct)
  • 55 diopters
  • 33 diopters
  • Which of the following contributes to the causes of corneal transparency?

  • High water content in the cornea
  • Presence of myelin sheath in the corneal nerve fibers
  • Irregular arrangement of corneal collagen bundles
  • Lack of vascularization in the cornea (correct)
  • What is the approximate diameter of the cornea?

  • 13 mm
  • 11 mm (correct)
  • 12 mm
  • 10 mm
  • Why is the refractive index the same in all corneal layers?

    <p>Regular arrangement of collagen bundles</p> Signup and view all the answers

    Which vitamin helps prevent keratinization of the cornea?

    <p>Vitamin A</p> Signup and view all the answers

    In maintaining corneal transparency, which pump is responsible for expelling fluid into the aqueous humor?

    <p>Metabolic pump</p> Signup and view all the answers

    What is the range of normal intraocular pressure (IOP) in humans?

    <p>15-20 mmHg</p> Signup and view all the answers

    Which structure separates the vitreous from the lens and allows slight bulging of the lens during accommodation?

    <p>Hyaloid canal</p> Signup and view all the answers

    What is the main function of the vitreous humor in the eye?

    <p>Maintains normal eye shape</p> Signup and view all the answers

    In the eye, what structure holds the lens in place behind the iris?

    <p>Suspensory ligament</p> Signup and view all the answers

    Which of the following is NOT a function of the vitreous humor?

    <p>Support vascularization of the eye</p> Signup and view all the answers

    What is the refractive index of the central part of the lens?

    <p>1.4</p> Signup and view all the answers

    Which drug increases the excitability of the third cranial nerve nucleus?

    <p>Morphine</p> Signup and view all the answers

    What is the diagnostic sign of morphine poisoning related to the pupil?

    <p>Pinpoint pupil</p> Signup and view all the answers

    Which drug causes marked dilation and cycloplegia of the pupil for a long time?

    <p>Atropine</p> Signup and view all the answers

    What is the mechanism of action of prostigmine?

    <p>(Anticholine esterase →↑ Acetylcholine concentration)</p> Signup and view all the answers

    In which condition does mydriasis occur?

    <p>Pheochromocytoma</p> Signup and view all the answers

    What are the changes that occur during accommodation in the eye?

    <p>(Increase in the convexity of mainly the anterior surface of the lens)</p> Signup and view all the answers

    What is the physiological blind spot in the visual field caused by?

    <p>Overlap between the visual fields of both eyes</p> Signup and view all the answers

    What is the central part of the macula lutea called?

    <p>Fovea centralis</p> Signup and view all the answers

    What is found in the fovea centralis that contributes to its high visual acuity?

    <p>Densely packed thin cones</p> Signup and view all the answers

    Which ion is continuously pumped from the inner segment of rods and cones to flow inside again at the outer segment?

    <p>Na+ (Sodium)</p> Signup and view all the answers

    What term is used to describe the movements of Na+ from the inner segment to enter into the outer segment of rods?

    <p>Dark current</p> Signup and view all the answers

    What causes continuous release of an inhibitory chemical transmitter when the eye is not exposed to light?

    <p>Low resting membrane potential (r.m.p)</p> Signup and view all the answers

    What enzyme is responsible for transforming cGMP into 5'GMP in photoreceptors?

    <p>cGMP phosphodiesterase</p> Signup and view all the answers

    What is the result of hyperpolarization in photoreceptors?

    <p>Increased release of inhibitory chemical transmitter</p> Signup and view all the answers

    Which type of receptor potential is generated by photoreceptors in the retina?

    <p>Hyperpolarization</p> Signup and view all the answers

    What leads to the re-synthesis of cGMP and the subsequent opening of Na+ channels in photoreceptors?

    <p>Removal of light (Dark)</p> Signup and view all the answers

    Which cell type is mainly responsible for color vision in the retina?

    <p>Cones</p> Signup and view all the answers

    How does the sense of discrimination of various wavelengths that constitute the visible spectrum occur?

    <p>Function of cones</p> Signup and view all the answers

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