Anatomy 2 Exam 1
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Questions and Answers

Which part of the lens invaginates to form the lens pit?

  • Optic vesicles
  • Lens placode (correct)
  • Surface ectoderm
  • Lens vesicle
  • On what day those the lens form during embryology?

  • 25th day
  • 26th day
  • 27th day (correct)
  • 28th day
  • What differentiates into primary lens cells and elongates anteriorly as fibers, toward the anterior lens epithelium to fill up the lumen?

  • Surface ectoderm
  • Posterior lens epithelium (correct)
  • Optic vesicles
  • Lens placode
  • What do young outer fibers of the lens contain?

    <p>Nuclei and organelles</p> Signup and view all the answers

    Where is the germinative zone located?

    <p>Just anterior to the equator</p> Signup and view all the answers

    Which part of the lens forms the fetal nucleus?

    <p>Anterior lens epithelium</p> Signup and view all the answers

    What do Y inverted sutures denote during slit lamp examination?

    <p>Boundaries of the fetal nucleus</p> Signup and view all the answers

    What is the main mass of the lens composed of?

    <p>Primary and secondary lens fibers</p> Signup and view all the answers

    What can cause a change in the shape of the lens, increasing its dioptric power for accommodation?

    <p>Ciliary muscle contraction</p> Signup and view all the answers

    What part of the eye is attached to the anterior vitreous face by Wieger’s ligament?

    <p>Lens capsule</p> Signup and view all the answers

    What is the anterior radius of curvature of the lens?

    <p>8-14 μm</p> Signup and view all the answers

    Where are Y inverted sutures seen during slit lamp examination?

    <p>Fetal nucleus</p> Signup and view all the answers

    What is the primary function of the lens?

    <p>To refract light</p> Signup and view all the answers

    What is the source of the energy required for cellular metabolism and cellular replication in the lens?

    <p>Anaerobic glycolysis</p> Signup and view all the answers

    What is the primary protector against oxidative damage in the lens?

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

    What is the effect of age changes on soluble lens proteins (alpha crystallins)?

    <p>Decrease in soluble lens proteins</p> Signup and view all the answers

    Which type of cataract is located just beneath the posterior capsule and impacts vision early?

    <p>Posterior subcapsular cataract</p> Signup and view all the answers

    What are the risk factors for cataract development according to the text?

    <p>High dose of steroids</p> Signup and view all the answers

    What is the primary cause of blindness according to the text?

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

    Which of the following mechanisms is presumed to be causative of cataracts?

    <p>Protein modification</p> Signup and view all the answers

    What does a nuclear cataract mainly consist of?

    <p>Embryonic fetal or adult nucleus</p> Signup and view all the answers

    What is the primary effect of ascorbic acid in relation to oxidative stress of the lens?

    <p>Prevents oxidative damage (anti-cataract effect)</p> Signup and view all the answers

    What does anaerobic glycolysis serve as a source for in lens metabolism?

    <p>Maintaining ATP activity in epithelial cells and newer fibers near the equator</p> Signup and view all the answers

    What is the impact of age changes on glutathione activity?

    <p>Decrease in glutathione activity</p> Signup and view all the answers

    What is the refractive power of the unaccommodated lens?

    <p>20 D</p> Signup and view all the answers

    Which part of the lens contains a higher concentration of crystallins?

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

    What is the approximate thickness of the thinnest region of the lens at the posterior pole?

    <p>3 μm</p> Signup and view all the answers

    Which part of the lens is responsible for secretion of the anterior capsule throughout life?

    <p>Anterior lens epithelium</p> Signup and view all the answers

    What is the name of the elastic acellular envelope that allows passage of small molecules into and out of the lens?

    <p>Lens capsule</p> Signup and view all the answers

    Which part of the lens contains fibers formed after sexual maturation?

    <p>Adult nucleus</p> Signup and view all the answers

    What is the primary function of the zonules of Zinn?

    <p>To attach the lens to the ciliary body</p> Signup and view all the answers

    What happens to the diameter of the ciliary ring in an emmetropic eye when viewing a distant object?

    <p>It increases</p> Signup and view all the answers

    During accommodation, what happens to the anterior chamber of the eye?

    <p>It becomes shallower</p> Signup and view all the answers

    What change occurs in the lens shape during accommodation?

    <p>The lens becomes more flattened</p> Signup and view all the answers

    What do lens fibers lose as they become compacted in the nucleus?

    <p>Cellular organelles and nuclei</p> Signup and view all the answers

    Where do zonules of Zinn arise from?

    <p>Basement membrane of the nonpigmented ciliary epithelium</p> Signup and view all the answers

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