OPT 2064 Ocular Biology: Retina Histology Overview
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Questions and Answers

What is the main function of the retina?

  • Transmitting taste signals to the brain
  • Processing olfactory signals for transmission
  • Processing electromagnetic energy in the retinal image into neural signals (correct)
  • Converting sound waves into neural signals

    • Which part of the eye supports the retina only at two regions?

  • Vitreous humor (correct)
  • Ora serrata
  • Optic nerve head
  • Choroid

    • Which layer of the retina is firmly attached at two regions, around the optic disc and at the ora serrata?

  • Pigment epithelium (correct)
  • Inner nuclear layer
  • Nerve fibre layer
  • Layer of rods and cones

    • What is the average thickness of the retina?

    <p>200μm</p> Signup and view all the answers

    Which layer of the retina forms a junction with the vitreous?

    <p>Internal limiting membrane</p> Signup and view all the answers

    What is the total area of the retina?

    <p>950mm2</p> Signup and view all the answers

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

    <p>To absorb stray light and provide a pathway for metabolites to the receptors</p> Signup and view all the answers

    What is the structure that links the outer segment to the inner segment of the photoreceptor cell?

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

    What is the total length of the outer & inner segments of both rods & cones?

    <p>60μm</p> Signup and view all the answers

    What is the composition of the outer segments in cones?

    <p>Series of discs formed by infolding of the cell membrane</p> Signup and view all the answers

    What fills all the extracellular space in the layer containing the cell membrane of the receptors and Müller cell membranes?

    <p>Muco-polysaccharide ground substance</p> Signup and view all the answers

    What is the function of the zonular adhesions linking the cell membrane of the receptors and Müller cell membranes?

    <p>Provide mechanical stability to the tips of the receptors</p> Signup and view all the answers

    What is present in the cell body of retinal pigment epithelium (RPE) cells?

    <p>Large amount of endoplasmic reticulum, mitochondria, &amp; melanin granules</p> Signup and view all the answers

    What does Bruch's membrane do?

    <p>Forms part of the basement membrane that adheres to RPE cells</p> Signup and view all the answers

    Where do rods replace cones entirely?

    <p>At the ora-serrata</p> Signup and view all the answers

    What is the structure that extends from the ora-serrata to the edge of the optic disc?

    <p>External limiting membrane</p> Signup and view all the answers

    What is the function of the extraocular muscles?

    <p>To enable high-velocity ocular movements</p> Signup and view all the answers

    Which muscle is responsible for moving the eye laterally?

    <p>Lateral rectus</p> Signup and view all the answers

    How does a muscle contraction initiate in the extraocular muscles?

    <p>Depolarization of the sarcolemma triggered by a nerve impulse</p> Signup and view all the answers

    What provides for the precise fine motor control of extraocular muscles?

    <p>Innervation of 3 to 10 fibers by each axon</p> Signup and view all the answers

    What characterizes the extraocular muscles compared to skeletal muscles?

    <p>Denser blood supply and delicate connective tissue sheaths</p> Signup and view all the answers

    What is the velocity of saccades, as supported by the extraocular muscles?

    <p>Up to 1000 degrees per second</p> Signup and view all the answers

    What is the first step in the sliding ratchet model of muscle contraction?

    <p>Calcium release</p> Signup and view all the answers

    Which event occurs after the binding of calcium ions to the troponin-tropomyosin complex in muscle contraction?

    <p>ATP breakdown</p> Signup and view all the answers

    What is the last step in the sliding ratchet model of muscle contraction?

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

    Which of the following represents the anatomical sequence of the spiral of Tillaux involving the extraocular muscles?

    <p>Medial rectus, inferior rectus, lateral rectus, superior rectus</p> Signup and view all the answers

    What is the function of the largest extraocular muscle, the medial rectus?

    <p>Moves the eye medially (adducts)</p> Signup and view all the answers

    What does ATP attachment enable in muscle contraction?

    <p>Formation of cross-bridges</p> Signup and view all the answers

    What initiates the exposure of an active site on the actin protein in muscle contraction?

    <p>Calcium release</p> Signup and view all the answers

    In muscle contraction, what causes the head to tilt towards the shaft of the myosin filament?

    <p>ATP breakdown</p> Signup and view all the answers

    Which structure marks the start and end points of the spiral of Tillaux involving extraocular muscles?

    <p>&quot;Limbus&quot;</p> Signup and view all the answers

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