Human Anatomy: Hearing and Vision Systems
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Questions and Answers

What fluid fills the cochlear duct?

  • Cerebrospinal fluid
  • Interstitial fluid
  • Perilymph
  • Endolymph (correct)

    • Which part of the basilar membrane is most responsive to high-frequency vibrations?

  • The apex
  • The portion nearest the oval window (correct)
  • The portion nearest the helicotrema
  • The middle portion

    • What are the hair-like projections located at the apical ends of hair cells called?

  • Stereocilia (correct)
  • Cilia
  • Flagella
  • Microtubules

    • What structure connects the tip of each stereocilium to the side of the next taller stereocilium within a hair bundle?

    <p>Tip link</p> Signup and view all the answers

    Where do the axons of the optic tract primarily synapse?

    <p>Lateral geniculate nuclei of the thalamus</p> Signup and view all the answers

    What is the function of optic radiations?

    <p>To transmit visual data from the thalamus to the visual cortex</p> Signup and view all the answers

    What type of ion channel is opened when stereocilia bend?

    <p>Potassium (K+) channels</p> Signup and view all the answers

    Which part of the visual field projects to the left side of the brain?

    <p>The right part of each visual field</p> Signup and view all the answers

    What is a key characteristic of binocular vision, based on the figure?

    <p>It results in depth perception from overlapping visual fields</p> Signup and view all the answers

    If a lesion occurred in the optic tracts, what structure would be most directly affected in terms of signal transmission?

    <p>The superior colliculi and geniculate nuclei</p> Signup and view all the answers

    What is the direct effect of light on rhodopsin in rod cells?

    <p>It breaks down rhodopsin, reducing its presence.</p> Signup and view all the answers

    What is the immediate consequence of cGMP being converted to GMP in a rod cell?

    <p>Rod cell hyperpolarization.</p> Signup and view all the answers

    What is the role of transducin in the phototransduction cascade?

    <p>It activates cGMP phosphodiesterase.</p> Signup and view all the answers

    What causes a rod cell to hyperpolarize?

    <p>Closing of sodium ion channels.</p> Signup and view all the answers

    Which event directly follows the reduction of glutamate release in a rod cell after exposure to light?

    <p>Stimulation of bipolar cells.</p> Signup and view all the answers

    Why does the eye take time to adapt when transitioning from a dark to a bright environment?

    <p>Chemical changes in rhodopsin levels must occur.</p> Signup and view all the answers

    In dark conditions, what changes occur in the rod cells?

    <p>Increase in rhodopsin levels, making the eye more sensitive.</p> Signup and view all the answers

    What is the primary function of the choroid in relation to vision?

    <p>To enhance visual acuity by reducing light scatter.</p> Signup and view all the answers

    What is the primary function of the pupils during light and dark adaptation?

    <p>To control the amount of light entering the eye.</p> Signup and view all the answers

    Which photoreceptor is primarily responsible for color vision and visual acuity?

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

    Where are rods primarily located in the retina?

    <p>Over most of the retina, absent in the fovea centralis</p> Signup and view all the answers

    Which photopigment is found in rods?

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

    Which of the following best describes the shape of rods and cones?

    <p>Rods are cylindrical, while cones are conical</p> Signup and view all the answers

    Which structure is located in the anterior compartment of the eye?

    <p>Anterior chamber</p> Signup and view all the answers

    What is the primary function of the aqueous humor?

    <p>Supplying nutrients to the lens and cornea</p> Signup and view all the answers

    In what conditions do rods primarily function?

    <p>Low light conditions</p> Signup and view all the answers

    Where are cones most numerous in the retina?

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

    Where is the posterior chamber located?

    <p>Between the iris and the lens</p> Signup and view all the answers

    What is the function of the pigment cell layer in the retina as illustrated?

    <p>To support and nourish the retinal cells</p> Signup and view all the answers

    What is the function of the vitreous humor?

    <p>To hold the lens and retina in place</p> Signup and view all the answers

    Which cell type acts as the first stage of light processing after photoreceptors?

    <p>Bipolar cells</p> Signup and view all the answers

    Where does the aqueous humor return to the venous circulation?

    <p>Through the canal of Schlemm</p> Signup and view all the answers

    What is the direction of light through the retina, as shown in the diagram?

    <p>From the pigmented layer towards the rod/cone layer</p> Signup and view all the answers

    Which of these is NOT a function of the anterior compartment?

    <p>Supporting the retina</p> Signup and view all the answers

    Glaucoma is characterized primarily by:

    <p>An abnormal increase in intraocular pressure</p> Signup and view all the answers

    Which of the following structures is part of the fibrous tunic of the eye?

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

    Which structure is NOT directly filled with perilymph?

    <p>Cochlear duct</p> Signup and view all the answers

    The basilar membrane forms the wall of which structure?

    <p>Scala tympani</p> Signup and view all the answers

    Which of these is the space between the vestibular and basilar membranes?

    <p>Cochlear duct</p> Signup and view all the answers

    Where are the stereocilia located?

    <p>On the hair cells</p> Signup and view all the answers

    What is the function of the endosteum of the inner ear?

    <p>It lines the bony labyrinth.</p> Signup and view all the answers

    Which structure is located within the cochlear duct?

    <p>The tectorial membrane</p> Signup and view all the answers

    Which structure within the inner ear is bone?

    <p>Spiral lamina</p> Signup and view all the answers

    Which is the correct sequence of structures, starting from the scala vestibuli?

    <p>Scala vestibuli → cochlear duct → scala tympani</p> Signup and view all the answers

    What is the main function of the round window?

    <p>To release pressure from the inner ear</p> Signup and view all the answers

    Which of the following structures is NOT part of the membranous labyrinth?

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

    Study Notes

    Chapter 15 Outline

    • Chapter 15 focuses on the lecture outline for Anatomy and Physiology, Eleventh Edition
    • Separate PowerPoint slides provide figures and tables without notes and animations.
    • The copyright for the content is held by McGraw Hill Education.

    Special Senses

    • Olfaction
    • Taste
    • Visual system
    • Hearing and balance

    15.1 Olfaction

    • Seven primary odors are now recognized, yet people can distinguish around 4000 different odors.
    • Olfactory hairs (cilia) of olfactory neurons are embedded in mucus.
    • Odorants dissolve in mucus, binding to receptors. The mechanism is unknown, but cilia depolarize triggering action potentials in olfactory neurons.
    • A single receptor can respond to multiple odors.
    • Olfactory epithelium regenerates; olfactory neurons are replaced by basal cells every two months.

    15.2 Taste

    • Papillae are bumps on the tongue.
    • Taste buds house supporting cells surrounding taste (gustatory) cells.
    • Taste cells have microvilli (gustatory hairs) extending into taste pores.
    • Taste cells are replaced about every 10 days.
    • Taste is closely associated with smell.

    Taste Types

    • Sour: Most sensitive receptors are on the lateral aspects of the tongue.
    • Salty: Most sensitivity with sweet, triggered by Na+ and other metal ions.
    • Bitter: Highest sensitivity receptors on posterior tongue, triggered by alkaloids (often toxins).
    • Sweet: Sensitivity triggered by sugars, some carbohydrates, and some proteins
    • Umami (Glutamate): Scattered sensitivity caused by amino acids.

    15.3 Visual System

    • Eyebrows: Shade and inhibit sweat.
    • Eyelids (palpebrae): have conjunctiva, palpebral fissure, and canthi (medial/lateral).
    • Eyelashes: double/triple row with ciliary glands (modified sweat glands) and Meibomian glands (produce sebum).
    • Conjunctiva: thin transparent mucous membrane, including palpebral and bulbar conjunctiva.
    • Layers of eyelid tissues include a tarsal plate to maintain shape.

    Anatomy of the Eye

    • Three Tunics: fibrous, vascular, and nervous.
    • Fibrous tunic: sclera and cornea
    • Vascular tunic: choroid, ciliary body, and iris
    • Nervous tunic: retina
    • Optic nerve carries information, connecting the eye to the brain.

    Lacrimal Apparatus

    • Tears are produced in the lacrimal gland.
    • Tears exit through several lacrimal ducts
    • Tears pass over the surface of the eye.
    • Tears enter lacrimal canaliculi.
    • Tears are carried through the lacrimal sac to the nasolacrimal duct.
    • Tears enter the nasal cavity.

    Extrinsic Eye Muscles

    • Various extrinsic muscles control eye movement. These include the Superior/Inferior Rectus, Superior/Inferior Oblique, and the Lateral/Medial Rectus muscles.

    Chambers of the Eye

    • Anterior compartment: anterior to the lens, occupied by the aqueous humor.
      • Anterior chamber: between the cornea and iris.
      • Posterior chamber: between the iris and the lens.
    • Aqueous humor: helps maintain intraocular pressure; delivers nutrients. Refracts light. Ciliary process produces aqueous humor.
    • Vitreous humor: posterior to lens. Jelly-like vitreous humor helps maintain intraocular pressure and holds the lens and retina in place; it refracts light.
    • Glaucomatous: increased intraocular pressure.

    15.4 Hearing and Balance

    • External ear: Auricle, external acoustic meatus, tympanic membrane.
    • Middle ear: air-filled space, auditory ossicles (malleus, incus, stapes), eustachian tube.
    • Inner ear: vestibular complex (vestibule, semicircular canals; responsible for equilibrium), and cochlea (responsible for hearing).

    Inner Ear

    • Labyrinths (bony and membranous)
    • Lymph filled: endolymph (within membranous labyrinth) and perilymph (space between bony and membranous labyrinth)
    • Oval/round windows
    • Cochlear chambers (scala vestibuli, scala media, scala tympani)
    • Spiral organ/Organ of Corti: contains hair cells and associated nerves.

    Auditory Function

    • Vibrations produce sound waves
    • Volume/loudness relates to wave amplitude.
    • Pitch relates to wave frequency.
    • Timbre relates to resonance quality or overtones.

    Muscles of the Middle Ear

    • Tensor tympani: inserts on the malleus and innervated by cranial nerve V.
    • Stapedius: inserts on the stapes and innervated by cranial nerve VII. (Attenuation reflex muscles that contract during loud noises preventing damage during vibrations.)

    Effect of Sound Waves on Cochlear Structures/Points Along the Basilar Membrane

    • Sound waves cause the tympanic membrane, malleus, incus, and stapes to vibrate.
    • Vibrations of the stapes and oval window cause vibrations in the perilymph of Scala Vestibuli.
    • Wave vibrations in perilymph propagate through scala tympani to the round window and dampened.

    Sensitivity of Hearing

    • The basilar membrane is important in pitch discrimination because it responds to different frequencies at different points of the cochlea.
    • Inner hair cells receive efferent inputs, causing them to change in length to enhance or diminish certain auditory inputs.
    • Outer hair cell responses to frequency range differences is important for tuning.

    15.5 Effects of Aging on the Special Senses

    • Slight loss in ability to detect odors
    • Decreased sense of taste
    • Lens's of eyes lose flexibility/accommodation.
    • Development of cataracts, macular degeneration, glaucoma, and diabetic retinopathy
    • Decline in visual acuity and color perception.

    Hearing and Balance Conditions

    • Conductive hearing loss (pathology in external/middle ear)
    • Sensorineural hearing loss (pathology of inner ear/cochlear nerve)
    • Otosclerosis (bones of middle ear fuse)
    • Tinnitus (phantom sound)
    • Otitis media (middle ear infection)
    • Inner ear infections
    • Motion sickness (conflict of inner ear/visual/balance cues)
    • Meniere disease (conflicts in inner ear/balance, fluid abnormality)

    Balance

    • Static labyrinth: utricle and saccule
      • Evaluates position of head relative to gravity
      • Detects linear acceleration/deceleration (as in a car)
    • Kinetic labyrinth: semicircular canals
      • Evaluates head movement in three-dimensional space

    Static Labyrinth

    • Utricle has macula oriented parallel to skull base.
    • Saccula has macula oriented perpendicular to skull base.
    • Macula: Specialized epithelium with stereocilia (microvilli) and kinocilium (embedded in gelatinous).
    • Otoliths (weighted structures) influence action potential rate based on gravity.
    • Patterns of stimulation provide information on head position and acceleration.

    Function of Vestibule in Maintaining Balance

    • Endolymph in utricle, gelatinous mass, and otoliths determine displacement in response of head/body movement.
    • Vestibular nerve fibers transmit action potentials from the macula depending on stimulation.

    Kinetic Labyrinth

    • Three semicircular canals filled with Endolymph: transverse, coronal, and sagittal planes
    • Movement initiates an action potential (most intense when the rate of head movement changes)
    • Movement changes translate into changes in action potential rate.

    Neuronal Pathways for Balance

    • Axons from vestibular ganglion pass vestibular to the vestibular nucleus.
    • Vestibular nuclei influence postural muscles.
    • Vestibular nuclei to other motor nuclei (oculomotor, trochlear, abducens) influence extrinsic eye muscles.
    • Thalamic neurons to vestibular area of the cortex.

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    Related Documents

    Chapter 15: Special Senses Lecture Outline (PDF)

    Description

    Test your knowledge on the intricate systems of hearing and vision in humans. This quiz covers various structures, functions, and processes related to the cochlea, optic tract, and phototransduction. Enhance your understanding of sensory biology and the complexities of anatomical functions.

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