Anatomy & Physiology ch 15
Anatomy & Physiology ch 15 Biol 2301
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Human Anatomy & Physiology, 8e (Marieb/Hoehn) Chapter 15 The Special Senses Matching Questions Figure 15.1 Using Figure 15.1, match the following: 1) Ganglion cells. Answer: E Diff: 1 Page Ref: 554; Fig. 15.6 2) Bipolar cells. Answer: C Diff: 1 Page Ref: 554; Fig. 15.6 3) Horizontal cell. Answer: A Diff: 1 Page Ref: 554; Fig. 15.6 4) Amacrine cell. Answer: D Diff: 1 Page Ref: 554; Fig. 15.6 5) Rod. 1 Copyright © 2010 Pearson Education, Inc. Answer: B Diff: 1 Page Ref: 554; Fig. 15.6 Figure 15.2 Using Figure 15.2, match the following: 6) Protects and shapes the eyeball; provides a sturdy anchoring site for extrinsic eye muscles. Answer: A Diff: 1 Page Ref: 551; Fig. 15.4 7) Blood vessels supply nutrition to all eye layers. Answer: B Diff: 1 Page Ref: 551; Fig. 15.4 8) Contains only cones; provides detailed color vision. Answer: D Diff: 1 Page Ref: 553; Fig. 15.4 9) Lacks photoreceptors; where optic nerve exits the eye. Answer: E Diff: 1 Page Ref: 553; Fig. 15.4 10) Consists of a pigmented layer and a neural layer. 2 Copyright © 2010 Pearson Education, Inc. Answer: C Diff: 1 Page Ref: 553; Fig. 15.4 Figure 15.3 Using Figure 15.3, match the following: 11) Acts as a reflexively activated diaphragm to vary pupil size. Answer: C Diff: 2 Page Ref: 551; Fig. 15.4 12) The only tissue in the body that can be transplanted from one person to another with little or no rejection. Answer: B Diff: 2 Page Ref: 551; Fig. 15.4 13) Controls lens shape. Answer: A Diff: 2 Page Ref: 551; Fig. 15.4 14) Holds the retina firmly against the pigmented layer. Answer: E Diff: 2 Page Ref: 555; Fig. 15.4 15) Fluid blockages cause glaucoma. Answer: D 3 Copyright © 2010 Pearson Education, Inc. Diff: 2 Page Ref: 555; Fig. 15.4 Figure 15.4 Using Figure 15.4, match the following: 16) Pinna. Answer: A Diff: 1 Page Ref: 575; Fig. 15.25 17) Tympanic membrane. Answer: E Diff: 1 Page Ref: 575; Fig. 15.25 18) Stapes. Answer: C Diff: 1 Page Ref: 575; Fig. 15.25 19) Semicircular canals. Answer: B Diff: 1 Page Ref: 575; Fig. 15.25 20) Cochlea. Answer: D Diff: 1 Page Ref: 575; Fig. 15.25 4 Copyright © 2010 Pearson Education, Inc. 21) Balance organ. Answer: B Diff: 1 Page Ref: 576; Fig. 15.25 5 Copyright © 2010 Pearson Education, Inc. 22) Houses organ of Corti. Answer: C Diff: 1 Page Ref: 577; Fig. 15.25 Match the following: A) Aqueous humor B) Retina C) Fovea centralis D) Lens 23) The sensory layer of the eye. Diff: 1 Page Ref: 553 24) The structure most responsible for focusing light rays that enter the eye. Diff: 1 Page Ref: 556 25) Helps maintain the intraocular pressure; located in the anterior part of the eye. Diff: 1 Page Ref: 555; Fig. 15.8 26) Area of greatest visual acuity. Diff: 1 Page Ref: 553 Answers: 23) B 24) D 25) A 26) C Match the following: A) Pharyngotympanic tube B) Tympanic membrane C) Otoliths D) Vestibule 27) Ear stones. Diff: 1 Page Ref: 584 28) Connects the middle ear with the nasopharynx. Diff: 1 Page Ref: 574 29) Separates external acoustic meatus from the middle ear. Diff: 1 Page Ref: 574 30) Contains utricle and saccule. Diff: 1 Page Ref: 576 31) Detects linear acceleration. 6 Copyright © 2010 Pearson Education, Inc. Diff: 1 Page Ref: 576 Answers: 27) C 28) A 29) B 30) D 31) D Match the following: A) Night blindness B) Glaucoma C) Conduction deafness D) Otitis media 32) A condition that can result from a deficiency of vitamin A. Diff: 2 Page Ref: 566 33) A condition of deafness that may result from otosclerosis. Diff: 2 Page Ref: 583 34) An inflammation of the lining of the middle ear. Diff: 2 Page Ref: 574 35) A condition often leading to blindness due to increased intraocular pressure. Diff: 2 Page Ref: 556 Answers: 32) A 33) C 34) D 35) B Match the following: A) Olfactory epithelium B) Crista ampullaris C) Macula D) Taste buds 36) Hair cells receptive to changes in dynamic equilibrium are found in this structure. Diff: 2 Page Ref: 585 37) Gustatory cells are found in this structure. Diff: 1 Page Ref: 571 38) Hair cells receptive to changes in static equilibrium are found in this structure. Diff: 2 Page Ref: 584 39) The receptors of olfaction are found in this structure. Diff: 1 Page Ref: 569570 Answers: 36) B 37) D 38) C 39) A 7 Copyright © 2010 Pearson Education, Inc. Match the following: A) Tympanic membrane B) Cochlear duct C) Spiral organ (of Corti) D) Vestibule 40) Houses the spiral organ (of Corti.) Diff: 1 Page Ref: 577 41) The receptor organ for hearing. Diff: 1 Page Ref: 580 42) The central part of the bony labyrinth. Diff: 1 Page Ref: 576 43) A membrane that transmits sound vibrations to the auditory ossicles. Diff: 1 Page Ref: 574 Answers: 40) B 41) C 42) D 43) A Match the following: A) Sensorineural deafness B) Tinnitus C) Conduction deafness 44) Loss of hearing resulting from prolonged exposure to highintensity sounds. Diff: 2 Page Ref: 583 45) Can result from the fusion of the auditory ossicles. Diff: 2 Page Ref: 583 46) A possible side effect of medications such as aspirin. Diff: 2 Page Ref: 583 47) One of the most common results of otitis media. Diff: 2 Page Ref: 583 48) Can result from impacted cerumen. Diff: 3 Page Ref: 583 Answers: 44) A 45) C 46) B 47) C 48) C 8 Copyright © 2010 Pearson Education, Inc. True/False Questions 1) The mucous membrane that lines the eyelids and is reflected over the anterior surface of the eyeball is the conjunctiva. Answer: TRUE Diff: 1 Page Ref: 549 2) Researchers have found that retinal ganglionic fields are of two types: on center or off center. Answer: TRUE Diff: 2 Page Ref: 567 3) The photoreceptor cells are sensitive to damage from light. Answer: TRUE Diff: 1 Page Ref: 561 4) Both the cornea and the lens are vascular. Answer: FALSE Diff: 1 Page Ref: 556 5) The optic disc is the location where the optic nerve leaves the eyeball. Answer: TRUE Diff: 1 Page Ref: 553 6) Sour taste receptors are stimulated by hydrogen ions of acidic food substances. Answer: TRUE Diff: 1 Page Ref: 573 7) The fluid contained within the membranous labyrinth is called perilymph. Answer: FALSE Diff: 1 Page Ref: 576 8) The extrinsic eye muscle motor units contain only 8 to 12 muscle cells and in some cases as few as 2 or 3 muscle cells. Answer: TRUE Diff: 2 Page Ref: 550551 9) Retinal detachment always results in loss of vision. Answer: FALSE Diff: 1 Page Ref: 553 10) The structure that allows equalization of the pressure in the middle ear with that outside the body is the external auditory meatus. Answer: FALSE Diff: 1 Page Ref: 574 9 Copyright © 2010 Pearson Education, Inc. 11) The bending of light rays is called reflection. Answer: FALSE Diff: 1 Page Ref: 557 12) The anterior chamber of the eye is filled with vitreous humor. Answer: FALSE Diff: 1 Page Ref: 555 13) The neural layer of the retina prevents excessive scattering of light within the eye. Answer: FALSE Diff: 1 Page Ref: 553 14) In order for sound to reach the spiral organ (of Corti), the auditory ossicles must vibrate the oval window and set the endolymph in motion. Answer: TRUE Diff: 1 Page Ref: 580 15) Sound is generally perceived in the occipital lobe of the cerebral cortex. Answer: FALSE Diff: 1 Page Ref: 582 16) Light passes through the entire thickness of the neural layer of the retina to excite the photoreceptors. Answer: TRUE Diff: 2 Page Ref: 557 17) Without a functioning crista ampullaris, the semicircular canals would not function. Answer: TRUE Diff: 2 Page Ref: 576 18) Contraction of the ciliary muscle causes the lens to bend the light less. Answer: FALSE Diff: 3 Page Ref: 551 19) Theoretically, an individual born without a middle ear would be able to hear by bone conduction with a hearing aid. Answer: TRUE Diff: 3 Page Ref: 574576 20) When we move from darkness to bright light, retinal sensitivity is lost, but visual acuity is gained. Answer: TRUE Diff: 3 Page Ref: 562 21) The function of the lens of the eye is to allow precise focusing of light on the retina. 10 Copyright © 2010 Pearson Education, Inc. Answer: TRUE Diff: 3 Page Ref: 556 22) Each olfactory cortical neuron receives input from one receptor at a time. Answer: FALSE Diff: 1 Page Ref: 570 23) Odorants must be volatile to be smelled. Answer: TRUE Diff: 1 Page Ref: 570 MultipleChoice Questions 1) What is the main function of the rods in the eye? A) depth perception B) color vision C) vision in dim light D) accommodation for near vision Answer: C Diff: 1 Page Ref: 553 2) What structure regulates the amount of light passing to the visual receptors of the eye? A) aqueous humor B) lens C) cornea D) iris Answer: D Diff: 1 Page Ref: 551552 3) Receptors for hearing are located in the ________. A) cochlea B) semicircular canals C) tympanic membrane D) vestibule Answer: A Diff: 1 Page Ref: 577 4) Which of the follow types of neurons are replaced throughout adult life? A) olfactory receptor cells B) retinal bipolar cells C) retinal ganglion cells D) auditory outer and inner hair cells Answer: A Diff: 2 Page Ref: 570 11 Copyright © 2010 Pearson Education, Inc. 5) The oil component found in tears is produced by the ________. A) lacrimal glands B) ciliary gland C) conjunctiva D) tarsal glands Answer: D Diff: 2 Page Ref: 549 6) The receptor for static equilibrium is the ________. A) semicircular canals B) macula C) utricle D) cochlear duct Answer: B Diff: 1 Page Ref: 584 7) Farsightedness is more properly called ________. A) myopia B) hypopia C) hyperopia D) presbyopia Answer: C Diff: 1 Page Ref: 559 8) Seventy percent of all sensory receptors are located in the ________. A) eye B) ears C) skin D) nose Answer: A Diff: 1 Page Ref: 548 9) Which of the following structures is not part of the external ear? A) pinna B) external acoustic meatus C) tympanic membrane D) pharyngotympanic tube Answer: D Diff: 1 Page Ref: 574 10) Nerve fibers from the medial aspect of each eye ________. A) go to the superior colliculus only B) pass posteriorly without crossing over at the chiasma C) divide at the chiasma, with some crossing and some not crossing D) cross over to the opposite side at the chiasma 12 Copyright © 2010 Pearson Education, Inc. Answer: D Diff: 2 Page Ref: 566 11) Ordinarily, it is not possible to transplant tissues from one person to another, yet corneas can be transplanted without tissue rejection. This is because the cornea ________. A) is not a living tissue B) has no nerve supply C) has no blood supply D) does not contain connective tissue Answer: C Diff: 2 Page Ref: 551 12) The oval window is connected directly to which passageway? A) scala vestibuli B) external acoustic meatus C) pharyngotympanic tube D) scala tympani Answer: A Diff: 2 Page Ref: 577 13) There are three layers of neurons in the retina. The axons of which of these neuron layers form the optic nerves? A) bipolar cells B) ganglion cells C) cone cells D) rod cells Answer: B Diff: 2 Page Ref: 553 14) The first "way station" in the visual pathway from the eye, after there has been partial crossover of the fibers in the optic chiasma, is the ________. A) superior colliculi B) lateral geniculate body of the thalamus C) visual cortex D) temporal lobe Answer: B Diff: 2 Page Ref: 568 15) As sound levels increase in the spiral organ (of Corti), ________. A) outer hair cells stiffen the basilar membrane B) outer hair cells bend the cilia away from the kinocilium C) inner hair cells stiffen the basilar membrane D) inner hair cells bend the cilia away from the kinocilium Answer: A Diff: 2 Page Ref: 581582 13 Copyright © 2010 Pearson Education, Inc. 14 Copyright © 2010 Pearson Education, Inc. 16) Which of the following is true about gustatory receptors? A) In order for a chemical to be sensed, it must be hydrophobic. B) The receptors generate an action potential in response to chemical stimuli. C) Complete adaptation occurs in about one to five minutes. D) All gustatory receptors have the same threshold for activation. Answer: C Diff: 2 Page Ref: 572 17) Taste buds are not found ________. A) in fungiform papillae B) in filiform papillae C) in circumvallate papillae D) lining the buccal cavity Answer: B Diff: 1 Page Ref: 571 18) Select the correct statement about olfaction. A) Olfactory receptors have a high degree of specificity toward a single type of chemical. B) Some of the sensation of olfaction is actually one of pain. C) Substances must be volatile and hydrophobic in order to activate olfactory receptors. D) Olfactory adaptation is only due to fading of receptor cell response. Answer: B Diff: 2 Page Ref: 570 19) What prevents the eyelids from sticking together when the eyes close? A) lacrimal fluid B) ciliary gland secretions C) tarsal gland secretions D) conjunctival fluid Answer: C Diff: 1 Page Ref: 549 20) Which of the following taste sensations is incorrectly matched to the chemicals that produce it? A) sweetorganic substances such as sugar and some lead salts B) souracids C) saltymetal ions D) bitteralkaloids E) umamiamino acids glutamate and lysine Answer: E Diff: 2 Page Ref: 571572 15 Copyright © 2010 Pearson Education, Inc. 21) U.S. employees must wear hearing protection at ________ dB or above. A) 100 B) 90 C) 80 D) 70 Answer: B Diff: 2 Page Ref: 580 22) What is a modiolus? A) bone in the center of a semicircular canal B) bone around the cochlea C) a bone pillar in the center of the cochlea D) a bony area around the junction of the facial, vestibular, and cochlear nerves Answer: C Diff: 1 Page Ref: 577 23) Which statement about malnutritioninduced night blindness is most accurate? A) The most common cause is vitamin D deficiency. B) Vitamin supplements can reverse degenerative changes. C) Visual pigment content is reduced in both rods and cones. D) The impaired vision is caused by reduced cone function. Answer: B Diff: 2 Page Ref: 566 24) Dark adaptation ________. A) is much faster than light adaptation B) results in inhibition of rod function C) involves improvement of acuity and color vision D) involves accumulation of rhodopsin Answer: D Diff: 2 Page Ref: 564566 25) Conscious perception of vision probably reflects activity in the ________. A) thalamus B) occipital lobe of the cortex C) chiasma D) superior colliculus Answer: B Diff: 2 Page Ref: 566 26) In the visual pathways to the brain, the optic radiations project to the ________. A) medial retina B) lateral geniculate body C) primary visual cortex D) optic chiasma 16 Copyright © 2010 Pearson Education, Inc. Answer: C Diff: 2 Page Ref: 566 27) Visual inputs to the ________ serve to synchronize biorhythms with natural light and dark. A) pretectal nuclei B) lateral geniculate body C) superior colliculi D) suprachiasmatic nucleus Answer: D Diff: 3 Page Ref: 566 28) Information from balance receptors goes directly to the ________. A) motor cortex B) visual cortex C) brain stem reflex centers D) back muscles Answer: C Diff: 2 Page Ref: 587 29) Motion sickness seems to ________. A) respond best to medication taken after salivation and pallor begins B) respond best to medication that "boosts" vestibular inputs C) result from activation of nausea centers in the brain stem D) result from mismatch between visual and vestibular inputs Answer: D Diff: 1 Page Ref: 587 30) In the uterus ________. A) the fetus cannot see and therefore visual cortical connections are not made B) the fetus can see only light and shadow, but not forms, so partial visual connections are made C) despite the fact that the fetus cannot see, functional visual cortical connections are established D) scanty visual connections are made that proliferate greatly during infancy Answer: C Diff: 1 Page Ref: 588 31) Most newborns ________. A) are myopic B) often use only one eye at a time C) see in tones of red and green only D) cry with copious tears Answer: B Diff: 1 Page Ref: 588 32) The blind spot of the eye is where ________. A) more rods than cones are found 17 Copyright © 2010 Pearson Education, Inc. B) the macula lutea is located C) only cones occur D) the optic nerve leaves the eye Answer: D Diff: 1 Page Ref: 553 33) The first vestiges of eyes in the embryo are called ________. A) mesenchyme B) optic discs C) optic vesicles D) optic cups Answer: C Diff: 1 Page Ref: 588 34) Which pairing of terms is incorrectly related? A) frequency: loudness B) quality: frequency number C) amplitude: sound intensity D) frequency: wavelength number Answer: A Diff: 2 Page Ref: 579580 35) Olfactory cells and taste buds are normally stimulated by ________. A) substances in solution B) stretching of the receptor cells C) the movement of otoliths D) movement of a cupula Answer: A Diff: 2 Page Ref: 569 36) Which of the following could not be seen as one looks into the eye with an ophthalmoscope? A) macula lutea B) optic chiasma C) fovea centralis D) optic disc Answer: B Diff: 2 Page Ref: 566 37) The cells of the retina in which action potentials are generated are the ________. A) rods and cones B) bipolar cells C) ganglion cells D) amacrine cells Answer: C Diff: 2 Page Ref: 553 18 Copyright © 2010 Pearson Education, Inc. 19 Copyright © 2010 Pearson Education, Inc. 38) During dark adaptation ________. A) the sensitivity of the retina decreases B) the rate of rhodopsin breakdown is accelerated C) rhodopsin accumulates in the rods D) the cones are activated Answer: C Diff: 2 Page Ref: 564566 39) Tinnitis, vertigo, and gradual hearing loss typify the disorder called ________. A) Ménière's syndrome B) conjunctivitis C) strabismus D) motion sickness Answer: A Diff: 2 Page Ref: 583 40) Which of the following is not a characteristic of olfactory receptor cells? A) They are ciliated. B) They are unipolar neurons. C) They are chemoreceptors. D) They have a short life span of about 60 days. Answer: B Diff: 2 Page Ref: 570 41) An essential part of the maculae involved in static equilibrium is (are) the ________. A) spiral organ (of Corti) B) cupula C) scala media D) otoliths Answer: D Diff: 2 Page Ref: 584 42) Which of the following is true about light and vision? A) Human photoreceptors respond to light in the 100300 nm range. B) When we see the color of an object, all light is being absorbed by that object except for the color being experienced. C) Light is a form of electromagnetic radiation that slows down as it enters a medium of relatively less density. D) The greater the incident angle of light striking a refractive surface, the less the amount of light bending. Answer: B Diff: 2 Page Ref: 556557 20 Copyright © 2010 Pearson Education, Inc. 43) The tarsal plate of the eyelid ________. A) is composed of connective tissue surrounding a thin cartilage plate B) is connected to the superior rectus muscle C) is connected to the levator palpebrae D) assists in the act of winking Answer: C Diff: 2 Page Ref: 548549 44) Which of the following is true about photoreceptors? A) Rods absorb light throughout the visual spectrum but confer only gray tone vision. B) In dim light, images are focused directly on the rods in the fovea centralis. C) Three types of colorsensitive photoreceptors exist: red, green, and yellow. D) If all cones are stimulated equally, all colors are absorbed by the cones and the color perceived is black. Answer: A Diff: 2 Page Ref: 559562 45) Select the correct statement about equilibrium. A) The weight of the endolymph contained within the semicircular canals against the maculae is responsible for static equilibrium. B) Cristae respond to angular acceleration and deceleration. C) Hair cells of both types of equilibrium hyperpolarize only, resulting in an increased rate of impulse transmission. D) Due to dynamic equilibrium, movement can be perceived if rotation of the body continues at a constant rate. Answer: B Diff: 2 Page Ref: 585 46) The eye muscle that elevates and turns the eye laterally is the ________. A) lateral rectus B) superior oblique C) inferior oblique D) medial rectus Answer: C Diff: 2 Page Ref: 550 47) The receptor membranes of gustatory cells are ________. A) basal cells B) gustatory hairs C) fungiform papillae D) taste buds Answer: B Diff: 2 Page Ref: 571 21 Copyright © 2010 Pearson Education, Inc. 48) Light passes through the following structures in which order? A) vitreous humor, lens, aqueous humor, cornea B) cornea, aqueous humor, lens, vitreous humor C) cornea, vitreous humor, lens, aqueous humor D) aqueous humor, cornea, lens, vitreous humor Answer: B Diff: 2 Page Ref: 557 49) Damage to the medial recti muscles would probably affect ________. A) refraction B) accommodation C) convergence D) pupil constriction Answer: C Diff: 2 Page Ref: 559 50) Which statement about sound localization is not true? A) It requires processing at the cortical level. B) It requires input from both ears. C) It uses time differences between sound reaching the two ears. D) It is difficult to discriminate sound sources in the midline. Answer: A Diff: 2 Page Ref: 583 51) Which of the following is not a possible cause of conduction deafness? A) impacted cerumen B) middle ear infection C) cochlear nerve degeneration D) otosclerosis Answer: C Diff: 2 Page Ref: 583 52) Visual processing in the thalamus does not contribute significantly to ________. A) depth perception B) highacuity vision C) night vision D) movement perception Answer: C Diff: 3 Page Ref: 566 53) Visible light fits between ________. A) X rays and UV B) gamma rays and infrared C) microwaves and radio waves D) UV and infrared 22 Copyright © 2010 Pearson Education, Inc. Answer: D Diff: 2 Page Ref: 556557 54) Ceruminous glands are ________. A) saliva glands found at the base of the tongue B) modified apocrine sweat glands C) glands found in the lateral corners of your eye D) modified taste buds Answer: B Diff: 1 Page Ref: 574 FillintheBlank/Short Answer Questions 1) The boundary of the retina is called the ________. Answer: ora serrata Diff: 1 Page Ref: 553 2) The synapse of the olfactory nerves with the mitral cells is called a ________. Answer: glomerulus Diff: 1 Page Ref: 570 3) The rocks found in one's head (calcium carbonate crystals) are called ________. Answer: otoliths Diff: 1 Page Ref: 584 4) The middle ear ossicle is the ________. Answer: incus Diff: 1 Page Ref: 576 5) The ________ are in the visual pathway and mediate the pupillary light reflexes. Answer: pretectal nuclei Diff: 1 Page Ref: 566 6) The oval window touches the stapes and the ________. Answer: scala vestibuli Diff: 2 Page Ref: 577 7) The vestibulocochlear nerve first synapses with the ________ in the medulla. Answer: cochlear nuclei Diff: 2 Page Ref: 582 8) The apex of the ear hears sounds in the range of ________ Hz. Answer: 20 Diff: 2 Page Ref: 579580 23 Copyright © 2010 Pearson Education, Inc. 9) In the optic ________ the visual fields of the axons are all ipsilateral. Answer: tract Diff: 2 Page Ref: 566 24 Copyright © 2010 Pearson Education, Inc. 10) Contrast light and dark adaptation and include the role of the rods and cones. Answer: Rods respond to lowintensity light that provides night and peripheral vision, while cones are brightlight, highdiscrimination receptors that provide color vision. During light adaptation, rods are inactivated and as cones respond to the highintensity light, high visual acuity results. In dark adaptation, cones do not function (visual acuity decreases) and rod function resumes when sufficient rhodopsin accumulates. Diff: 3 Page Ref: 564 11) What is the chemical composition of the rod pigment, rhodopsin, and how does it appear to act in the reception of light? Answer: Rhodopsin is a combination of retinal and scotopsin. Retinal is chemically related to vitamin A and is synthesized from it. Retinal can form a variety of threedimensional forms called isomers. The opsin protein combines with the 11cis retinal to form rhodopsin. The light triggered changes in retinal cause hyperpolarization of the rods. This happens because the light turns off sodium entry, which then inhibits the release of neurotransmitter, thus turning off electrical signals. Diff: 3 Page Ref: 562 12) After head trauma from an automobile accident, a man has anosmia. Define anosmia. Why is this condition fairly common after such injuries and in cases of severe nasal cavity inflammation? Answer: Anosmia means the loss of chemical sense of smell due to some olfactory disorder. Most anosmia results from head injuries or nasal cavity inflammations, allergies, smoking, and aging. The olfactory pathways are very sensitive to irritations or to damage, especially if the ethmoid bones have been damaged due to trauma. Diff: 3 Page Ref: 573 13) Explain why your nose runs during and immediately after a good cry. Answer: The tears flow into the lacrimal canaliculi and then into the nasolacrimal sac. As the sac fills, the tears begin to run down the nasolacrimal duct and out your nose. Diff: 2 Page Ref: 549 14) Trace the pathway of sound as it enters the external ear until it is perceived in the brain. Answer: A sound wave passing through the external acoustic meatus causes the eardrum to vibrate at the same frequency as the wave. The auditory ossicles amplify and deliver vibrations to the oval window. Pressure waves in the cochlear fluids cause basilar membrane resonance that stimulates the hair cells of the spiral organ (of Corti). Impulses are then generated along the cochlear nerve that travel to the cochlear nuclei of the medulla and, from there, through several brain stem nuclei to the auditory cortex of the brain. Diff: 3 Page Ref: 580582 15) Explain the role of the endolymph of the semicircular canals in activating the receptors during angular motion. Answer: The crista ampullaris responds to changes in the velocity of head movement (angular acceleration). The crista consists of a tuft of hair cells whose microvilli are embedded in the 25 Copyright © 2010 Pearson Education, Inc. gelatinous cupula. Rotational movement causes the endolymph to flow in the opposite direction, thus bending the cupula and exciting the hair cells. Diff: 3 Page Ref: 584585 16) What two things does the ciliary body do? Answer: 1. Constriction of the ciliary muscle that is attached to the lens via the ciliary zonule causes the lens to change shape. 2. The epithelium of the ciliary body secretes aqueous humor. Diff: 2 Page Ref: 551 17) When you go to the fair and ride the roller coaster, where do those wild sensations come from? Answer: The wild sensations occur when the receptor for dynamic equilibrium, the crista ampularis, is excited by endolymph moving in the semicircular canals. This movement is the result of rotational acceleration or deceleration. Many times these wild rides spin us around enough that our eyes tell us we are going one way but the vestibule and semicircular canal tell us something different. Conflicts like that can often cause us to get quite dizzy or even sick. Diff: 3 Page Ref: 585586 18) What is the pharyngotympanic tube and what is its purpose? Answer: The pharyngotympanic tube links the middle ear cavity with the nasopharynx. Normally it is flattened and closed, but swallowing or yawning opens it briefly to equalize pressure in the middle ear cavity with external air pressure. Diff: 3 Page Ref: 574 19) Explain why prolonged periods of reading tire the eye muscles and result in eye strain. Answer: Reading or other close work requires almost continuous accommodation, papillary constriction, and convergence, which lead to tiredness of the eye muscles. Diff: 2 Page Ref: 559 20) Where in the body is the only place where small blood vessels can be observed directly in a living person? Answer: fundus of the eye Diff: 2 Page Ref: 553 21) Distinguish between the maculae and cristae ampullaris in terms of their sensory reception. Answer: Maculae are sensory receptors for static equilibrium. They monitor the position of the head in space by responding to linear acceleration forces. Cristae ampullaris respond to rotary (angular) movements. Diff: 2 Page Ref: 584585 26 Copyright © 2010 Pearson Education, Inc. Clinical Questions 1) Roger went for his yearly eye examination and was informed that his intraocular pressure was slightly elevated (at 22 mm Hg). The physician expressed concern over this condition and noted that if the condition got worse, eyedrops would be merited. What is wrong with Roger's eyes, and what are the possible consequences of this condition? Explain the function of eyedrops used for therapy. Answer: If the drainage of the aqueous humor is blocked, pressure within the eye can increase, causing compression of the retina and optic nerve, resulting in a condition called glaucoma. The resulting destruction of the neural structures causes blindness unless the condition is detected early. Early glaucoma can be treated with eyedrops that increase the rate of aqueous humor drainage or decrease its production. Diff: 3 Page Ref: 556 2) Baby Susie's pediatrician notices that one of her eyes rotates outward and that she does not appear to be using it for vision. What is her condition and what does the pediatrician recommend? Answer: Susie has strabismus, caused by congenital weakness of the external eye muscles in her affected eye. To prevent this eye from becoming functionally blind, the doctor will recommend either eye exercises or putting a patch on the unaffected eye to force her to use the affected eye. If her case is deemed severe, surgery on the eye muscles will be recommended. Diff: 3 Page Ref: 551 3) A 60yearold woman is experiencing vertigo. She ignores the symptoms initially, but now her attacks are accompanied by severe nausea and vomiting. Following an attack, she hears a crackling in her ears that causes temporary deafness for some time after. What do you think her problem is, and what is its suspected cause? Answer: She most likely has a condition known as Ménière's syndrome. It affects both the semicircular canals and the cochlea. The cause of the syndrome is uncertain, but it may result from distortion of the membranous labyrinth by excessive endolymph accumulation. Less severe cases can usually be managed by antimotion drugs. For more debilitating attacks, salt restriction and diuretics are used to decrease overall extracellular fluid volumes. Diff: 3 Page Ref: 583 4) Ling, a 75yearold grandmother, complained that her vision was becoming obscured. Upon examination by an ophthalmologist she was told she had cataracts. What are they, how do they occur, and how are they treated? Answer: A cataract is a clouding of the lens that causes the world to appear distorted, as if looking through frosted glass. Some cataracts are congenital, but most are due to agerelated hardening and thickening of the lens, or are a possible consequence of diabetes mellitus. The direct cause is probably inadequate delivery of nutrients to the deeper lens fibers. The metabolic changes that result are thought to promote unfolding of the lens proteins. Unprotected exposure to the UV rays of sunlight over time is also associated with cataract formation. The lens can be removed and replaced with an artificial lens. Diff: 3 Page Ref: 556 27 Copyright © 2010 Pearson Education, Inc. 5) A nurse is administering Pilocarpine eye drops. The nurse instructs the patient to press on the nasolacrimal duct for 30 seconds because the medication can have some systemic side effects, such as affecting the heart rate. Explain the rationale for pressing on the nasolacrimal duct. Answer: Applying gentle pressure to the nasolacrimal duct prevents the delivery of the drug to the nasal mucosa and general circulation, where it may affect heart rate. Diff: 3 Page Ref: 549 28 Copyright © 2010 Pearson Education, Inc.
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