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Vascular Layer of the Eyeball quiz #1

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  • What are the three main components of the vascular layer (uvea) of the eye, and what is the primary function of each?
    The three main components are the iris (controls the amount of light entering the eye by adjusting pupil size), the ciliary body (suspends the lens, produces aqueous humor, and adjusts lens shape for focusing), and the choroid (provides blood supply to the retina and absorbs excess light to prevent reflection within the eye).
  • How does the iris control the size of the pupil, and what is the role of the autonomic nervous system in this process?
    The iris controls pupil size using two muscles: the pupillary constrictor (circular muscle for constriction) and the pupillary dilator (radial muscle for dilation). The parasympathetic division of the autonomic nervous system causes constriction in bright light or close vision, while the sympathetic division causes dilation in dim light or during emotional states like fear.
  • What determines eye color, and why do some eyes appear blue or green despite the absence of blue or green pigments?
    Eye color is determined by the amount of melanin in the iris. High melanin results in brown eyes, while low melanin leads to blue or green eyes. Blue and green colors are due to light refraction and scattering in the iris, not the presence of blue or green pigments.
  • Describe the structure and function of the ciliary body in the eye.
    The ciliary body consists of ciliary muscles (which change lens shape for focusing), ciliary zonules (suspensory ligaments connecting the lens to the muscles), and ciliary processes (which secrete aqueous humor for the anterior eye).
  • What is the function of the choroid in the vascular layer of the eye?
    The choroid is a pigmented, vascular membrane that supplies blood to the retina and absorbs excess light to prevent internal reflection, helping to maintain clear vision.
  • What are the three main components of the vascular layer (uvea) of the eye, and what is the primary function of each?
    The iris controls light entry by adjusting pupil size, the ciliary body suspends the lens and produces aqueous humor, and the choroid supplies blood to the retina and absorbs excess light.
  • How does the iris control the size of the pupil, and what is the role of the autonomic nervous system in this process?
    The iris uses the pupillary constrictor (circular muscle) to constrict and the pupillary dilator (radial muscle) to dilate the pupil; the parasympathetic nervous system causes constriction, while the sympathetic system causes dilation.
  • What determines eye color, and why do some eyes appear blue or green despite the absence of blue or green pigments?
    Eye color is determined by the amount of melanin in the iris; blue and green eyes result from light refraction and scattering, not from blue or green pigments.
  • Describe the structure and function of the ciliary body in the eye.
    The ciliary body includes ciliary muscles (change lens shape for focusing), ciliary zonules (suspensory ligaments connecting lens to muscles), and ciliary processes (secrete aqueous humor for the anterior eye).
  • What is the function of the choroid in the vascular layer of the eye?
    The choroid is a pigmented, vascular membrane that supplies blood to the retina and absorbs excess light to prevent internal reflection, maintaining clear vision.
  • Which part of the eye contains blood vessels that supply blood to the retina?
    The choroid, which is part of the vascular layer (uvea) of the eye, contains blood vessels that supply blood to the retina.