Ocular Anatomy and Physiology TS1
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Questions and Answers

What is the purpose of phosphorylation in the phototransduction cascade?

  • To amplify the signal
  • To activate rhodopsin
  • To inactivate rhodopsin (correct)
  • To reform cGMP
  • What is the result of the decrease in intracellular cGMP in photoreceptors?

  • Increase in glutamate release
  • Activation of transducin
  • Opening of CNG channels
  • Closure of CNG channels (correct)
  • What is the role of transducin in the phototransduction cascade?

  • To activate rhodopsin
  • To activate phosphodiesterase 6 (correct)
  • To hydrolyze cGMP
  • To release glutamate
  • What is the effect of light on rhodopsin?

    <p>It causes rhodopsin to change into metarhodopsin II</p> Signup and view all the answers

    What is the purpose of guanylyl cyclase in the recovery phase of the phototransduction cascade?

    <p>To reform cGMP</p> Signup and view all the answers

    What is the conformational change in the chromophore of rhodopsin upon photon absorption?

    <p>From 11-cis-retinal to 11-trans-retinal</p> Signup and view all the answers

    What is the primary function of phosphodiesterase 6 (PDE6) in the phototransduction cascade?

    <p>To hydrolyze cGMP to 5'-GMP</p> Signup and view all the answers

    What is the role of arrestin in the phototransduction cascade?

    <p>To inactivate rhodopsin</p> Signup and view all the answers

    What is the effect of lower intracellular Ca2+ levels in the recovery phase?

    <p>Activation of guanylyl cyclase</p> Signup and view all the answers

    What is the result of the activation of several hundred transducin molecules by metarhodopsin II?

    <p>Amplification of the signal by guanosine triphosphate (GTP)</p> Signup and view all the answers

    What is the primary function of the retinal pigment epithelium (RPE)?

    <p>To nourish and collect waste products from the photoreceptor layer</p> Signup and view all the answers

    What is the structure that provides the highest visual acuity?

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

    What is the approximate number of cones in the human retina?

    <p>6 million</p> Signup and view all the answers

    What is the purpose of the Henle's fiber layer in the retina?

    <p>To process signals from foveal and parafoveal photoreceptors</p> Signup and view all the answers

    What is the function of the inner segment of photoreceptor cells?

    <p>To synthesize components for outer segment renewal</p> Signup and view all the answers

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