Sense of Vision Learning Outcomes
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Questions and Answers

What is the primary function of the lens in the eye?

  • To control the amount of light entering the eye
  • To produce aqueous humor
  • To protect the eye from external damage
  • To bend light rays and focus them on the retina (correct)

    • Cataracts are primarily caused by bacterial infections of the eye.

    False (B)

    What process allows the eye to focus on objects at different distances by changing the shape of the lens?

    accommodation

    The majority (75%) of light refraction in the eye occurs at the ________.

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

    What happens to the lens when focusing on a close object?

    <p>It becomes more convex. (D)</p> Signup and view all the answers

    The image formed on the retina is upright and in the correct orientation.

    <p>False (B)</p> Signup and view all the answers

    What structure controls the thickness of the lens?

    <p>ciliary muscle</p> Signup and view all the answers

    Match the following terms with their description:

    <p>Refraction = Bending of light rays Accommodation = Adjustment in lens shape to focus at different distances Ciliary Muscle = Controls lens thickness Cornea = Primary site of light refraction</p> Signup and view all the answers

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

    <p>Keeps the retina attached to the choroid (C)</p> Signup and view all the answers

    The vitreous humor is constantly replaced throughout life.

    <p>False (B)</p> Signup and view all the answers

    What is the main cause of blindness in people under 65 years old?

    <p>diabetic retinopathy</p> Signup and view all the answers

    Age Related Macular Degeneration results in loss of vision in the center of the visual field, also known as the ____.

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

    Which layer of the eye contains photoreceptors?

    <p>Retina (D)</p> Signup and view all the answers

    Match the following eye conditions with their descriptions:

    <p>Retinal detachment = Retina peels away from its underlying layer Diabetic retinopathy = Blood vessels become blocked or damaged Age-related macular degeneration = Loss of vision in the center of the visual field Glaucoma = Aqueous humor does not flow out properly</p> Signup and view all the answers

    The space between the cornea and the iris is the posterior chamber.

    <p>False (B)</p> Signup and view all the answers

    What substance is found in the posterior cavity of the eye?

    <p>vitreous humor</p> Signup and view all the answers

    What type of color blindness is characterized by the absence of either red or green cones?

    <p>Red-green color blindness (D)</p> Signup and view all the answers

    The optic chiasma is where optic nerve fibers cross in the brain.

    <p>True (A)</p> Signup and view all the answers

    What is the clear mucous membrane that covers the white part of the eye?

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

    The structure in the fibrous tunic known as the 'white' of the eye is called the ______.

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

    Match the following components of the eye with their respective functions:

    <p>Cornea = Refracting and focusing light rays Lacrimal gland = Secreting tears Vitrous humor = Filling the posterior cavity Aqueous humor = Filling the anterior cavity</p> Signup and view all the answers

    Which humor is characterized as a soft, colorless, transparent, jelly-like substance?

    <p>Vitreous humor (B)</p> Signup and view all the answers

    The ciliary process is responsible for producing aqueous humor.

    <p>True (A)</p> Signup and view all the answers

    When the aqueous humor does not flow out of the eye properly, it can lead to ______.

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

    What type of lens is used to correct myopia?

    <p>Concave lens (A)</p> Signup and view all the answers

    Cones are responsible for black-and-white vision in dim light.

    <p>False (B)</p> Signup and view all the answers

    What happens during the light phase of rhodopsin?

    <p>Rhodopsin breaks down into opsin and retinal.</p> Signup and view all the answers

    The inward movement of the eyes is known as __________.

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

    Match the following types of vision conditions with their descriptions:

    <p>Myopia = Nearsightedness, image focused in front of the retina Hyperopia = Farsightedness, image focused behind the retina Astigmatism = Refraction abnormality due to irregular curvature Night blindness = Vision impairment due to low rhodopsin levels</p> Signup and view all the answers

    Which type of photoreceptor is more concentrated in the central fovea?

    <p>Cones (A)</p> Signup and view all the answers

    What causes night blindness?

    <p>Prolonged vitamin A deficiency leading to low rhodopsin levels.</p> Signup and view all the answers

    Astigmatism is caused by an uneven curvature of the lens or cornea.

    <p>True (A)</p> Signup and view all the answers

    Which of the following is NOT considered an accessory organ of the eye?

    <p>Retina (D)</p> Signup and view all the answers

    The orbicularis muscle raises the upper eyelids.

    <p>False (B)</p> Signup and view all the answers

    What substance found in tears helps to fight bacteria?

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

    The 'white' of the eye is known as the ______.

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

    Match the following eye structures with their primary function:

    <p>Cornea = Bends light rays entering the eye Iris = Regulates the amount of light entering the eye Retina = Converts light into nerve impulses Lens = Focuses light on the retina</p> Signup and view all the answers

    Where are the photoreceptors located?

    <p>Retina (B)</p> Signup and view all the answers

    The ciliary muscle helps to regulate the amount of light entering the eye.

    <p>False (B)</p> Signup and view all the answers

    What is the name of the area in the retina that contains a high concentration of cones?

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

    The ______ is the opening through which light enters the eye.

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

    Match the following structures with their descriptions:

    <p>Rods = Specialized for black and white vision. Cones = Responsible for color vision Optic disc = Blind spot of the vision Macula lutea = Area of sharpest vision</p> Signup and view all the answers

    What is the function of the lacrimal gland?

    <p>To produce tears (A)</p> Signup and view all the answers

    The vitreous humor is found in the anterior segment of the eye.

    <p>False (B)</p> Signup and view all the answers

    What is the name of the clear, convex structure on the front of the eye?

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

    The lens separates the internal cavity of the eye into the anterior and ______ segments.

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

    Match the tunic of the eye with its description:

    <p>Fibrous Tunic = Outer coat of the eyeball Vascular Tunic = Middle layer of the eyeball Sensory Tunic = Innermost layer of the eyeball</p> Signup and view all the answers

    Study Notes

    Sense of Vision Learning Outcomes

    • Students should be able to describe the accessory structures of the eye and their functions
    • Students should be able to describe the anatomy of the eye
    • Students should be able to describe the anatomy of eye cavities and their chambers
    • Students should be able to discuss the refraction of light and image formation
    • Students should be able to describe the stimulation of photoreceptors
    • Students should be able to discuss the visual pathway to the brain

    Introduction

    • More than half of the sensory receptors in the human body are located in the eyes
    • A large portion of the cerebral cortex is devoted to processing visual information
    • The eye is the organ of sight, located in the orbital cavity and supplied by the optic nerve (cranial nerve 2)

    Accessory Organs of the Eyes

    • Eyebrows/eyelashes - protect the eyeballs from foreign objects, sweat and direct sunlight
    • Eyelids - protect the eyes from excessive light and injury, and keep the cornea moist. The orbicularis muscle closes the lids, and the levator palpebrae superioris muscle raises the upper eyelids.
    • Conjunctiva - a thin mucous membrane that lines the inner aspect of the eyelids and is reflected onto the anterior surface of the eyeball.
    • Lacrimal apparatus - produces and drains tears. It consists of the lacrimal gland, lacrimal canal, lacrimal sac, and nasolacrimal ducts. Tears contain salt, water, and lysozyme.
    • Extraocular muscles - six muscles connected to the sclera which move the eyeballs in all directions

    Anatomy of the Eye

    • The walls of the eyeball consist of three layers of tunics: fibrous tunic (sclera and cornea), vascular tunic (choroid, ciliary body, and iris), and nervous tunic (retina)
    • The internal cavity is filled with fluids called humors. The lens separates the internal cavity into posterior and anterior segments. The anterior segment contains the aqueous humor. The posterior segment contains the vitreous humor.
    • Fibrous tunic is the outer coat of the eyeball and protects the intraocular contents. It is divided into sclera and cornea. At the junction of the sclera and cornea is the scleral venous sinus (canal of Schlemm).
    • The sclera is the "white" of the eye, maintaining its shape and providing attachment to the extrinsic muscles.
    • The cornea is part of the fibrous tunic; it is continuously from the sclera and refracts light rays. LASIK is a common visual corrective procedure on the cornea.

    Vascular Tunic (Uvea)

    • The middle layer composed of choroid, ciliary body, and iris.
    • Choroid lines between the sclera and retina, contains blood vessels to nourish the retina, and melanocytes to produce melanin to absorb light rays, preventing scattering within the eyeball.
    • Ciliary body consists of ciliary processes and ciliary muscles which secrete aqueous humor and change the shape of the lens to adapt for near/far vision.
    • Iris is the colored portion, and the pupil is the black hole. The iris regulates the amount of light entering the eye.

    Sensory Tunic (Retina)

    • The innermost layer, a delicate, transparent membrane, receives light and converts it into nerve impulses.
    • Divided into optic disc (blind spot), macula lutea, and peripheral retina.
    • The fovea centralis is the point of sharpest vision in the retina, characterized by a high concentration of cones.
    • Rods are photoreceptors sensitive to dim light for black and white vision and shapes and movement. Rhodopsin is the photopigment in rods.
    • Cones are specialized for color vision and sharpness in bright light. There are three types of cones (blue, green, and red). Intermediate colors are perceived by activation of more than one type of cone.

    Visual Pathway

    • After light stimulation, rods and cones trigger electrical signals to ganglion cells.
    • The impulses are conveyed through the retina to the optic nerve, the optic chiasma, then optic tracts, and to the thalamus.
    • From the thalamus, impulses travel along the optic radiations to the visual cortex in the occipital lobe of the brain.

    Clinical Applications (various sections)

    • Conjunctivitis: inflammation of the conjunctiva
    • Watery eyes: obstruction of the nasolacrimal ducts
    • Glaucoma: improper flow of aqueous humor
    • Cataracts: a clouding of the lens
    • Retinal detachment: occurs when the retina peels away from its support tissue
    • Diabetic retinopathy: damage to the retinal blood vessels caused by diabetes.
    • Age-Related Macular Degeneration (AMD): vision loss in the central visual field (macula) due to retinal damage

    Pathway of Light and Refraction

    • Refraction is the bending of light rays.
    • The refractive media of the eye (cornea, aqueous humor, lens, and vitreous humor) bend light rays to focus on the retina.
    • Images formed on the retina are upside down and backward, but the brain corrects this.

    Accommodation

    • Accommodation is adjusting the lens shape to focus images properly on the retina.
    • For near vision, the ciliary muscle contracts, suspensory ligaments relax, and the lens thickens (bulges).
    • For far vision, the ciliary muscle relaxes, suspensory ligaments become taut, and the lens flattens.

    Pupillary Response

    • The pupil, an opening in the iris, is regulated by radial and circular muscles.
    • Contraction of the circular muscles causes the pupil to constrict.
    • Contraction of the radial muscles causes the pupil to dilate.

    Convergence

    • Convergence is the inward movement of the eyes to focus on a close object.
    • The nearer the object, the greater the degree of convergence needed.
    • Extrinsic eye muscles bring about convergence.

    Refraction Abnormalities

    • Myopia (nearsightedness): image focuses in front of the retina (corrected with concave lenses).
    • Hyperopia (farsightedness): image focuses behind the retina (corrected with convex lenses).
    • Astigmatism: irregular curvature of the cornea or lens causing blurry vision (corrected with specialized lenses).

    Recap/Quiz (various sections)

    • Contains questions about the material covered to assess understanding. Questions cover structures, functions, clinical conditions, and measurements.

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    6.1 Sense of Vision PDF - Anatomy and Physiology 2

    Description

    This quiz covers the anatomy of the eye, including its accessory structures and functions. Students will explore concepts such as light refraction, image formation, and the visual pathway to the brain. Test your understanding of how our eyes work and their role in sensory perception.

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