Chapter 6
The Peripheral Nervous System: Afferent Division; Special Senses
TEST QUESTIONS
Multiple Choice
1. Afferent input that does not reach the conscious level is:
(a) somatic. (b) proprioceptive. (c) somethetic. (d) a special sense. (e) visceral.
ANSWER: e
2. Conscious interpretation of external stimuli: (a) is sensation.
(b) rarely occurs. (c) is perception.
(d) is processed in the diencephalon. (e) none of these answers.
ANSWER: c
3. The conversion of stimuli into neuron potentials (a) requires an adequate level of stimulus. (b) is called transduction.
(c) stems from generation of receptor potentials. (d) all of these answers.
(e) none of these answers.
ANSWER: d
4. Receptors:
(a) respond to various physical or chemical changes in their environment.
(b) change other forms of energy into electrical energy.
(c) respond more readily to their adequate stimulus.
(d) are found at the peripheral endings of afferent neurons.
(e) all of these answers.
ANSWER: e
5. Which of the following statements concerning receptors is correct?
(a) The larger the receptor potential, the greater the frequency of action potentials initiated in the afferent neuron.
(b) Tonic receptors often exhibit an “off-response.”
(c) Phasic receptors are important in situations where maintained information about a stimulus is valuable.
(d) Receptor adaptation results from nerve fatigue. (e) Receptors are part of efferent neurons.
ANSWER: a
6. Receptors:
(a) may be either a specialized ending of an afferent neuron or a special cell closely associated with the peripheral ending of an afferent neuron. (b) are present for every modality in the environment.
(c) when stimulated bring about opening of Na+
channels in the afferent neuron membrane adjacent to the receptor.
(d) two of these answers. (e) all of these answers.
ANSWER: d
7. Which of the following statements concerning receptor potentials is correct? Receptor potentials: (a) are usually depolarizations of receptors in response to adequate stimuli.
(b) are graded potentials.
(c) occur in neuronal cell bodies upon summation of pre synaptic input.
(d) both (a) and (b) above. (e) all of these answers.
ANSWER: d
8. Receptors:
(a) generate action potentials in afferent fibers in response to stimuli.
(b) change other forms of energy into electrical energy.
(c) are located in the dorsal root ganglion. (d) both (a) and (b) above.
(e) all of these answers.
ANSWER: d
(a) respond only to mechanical damage such as cutting, crushing, or pinching.
(b) transmit impulses along A-delta fibers. (c) activate the slow pain pathway. (d) release prostaglandins.
(e) none of these answers.
ANSWER: c
10. Phasic receptors:
(a) exhibit an “off-response.”
(b) signal a change in stimulus intensity. (c) are rapidly adapting receptors. (d) all of these answers.
(e) none of these answers.
ANSWER: d
11. Tonic receptors: (a) adapt rapidly.
(b) frequently exhibit an “off-response.” (c) can measure the degree of joint flexion. (d) all of these answers.
(e) none of these answers.
ANSWER: c
12. Which of the following receptors are rapidly adapting?
(a) muscle stretch receptors. (b) tonic receptors.
(c) phasic receptors.
(d) both muscle stretch receptors and tonic receptors
(e) all of these answers.
ANSWER: c
13. Pacinian corpuscles:
(a) adapt as a result of the physical features of the receptor.
(b) detect temperature. (c) are tonic receptors.
(d) do not display an “off-response.” (e) measure the degree of joint flexion.
ANSWER: a
14. Coding of sensory information may result from: (a) intensity of the stimuli.
(b) location of the stimuli. (c) stimulus modality. (d) all of these answers. (e) none of these answers.
ANSWER: d
15. In somatosensory pathways where do first-order neurons usually synapse with second-order neurons?
(a) dorsal root ganglia. (b) medulla oblongata. (c) spinal cord.
(d) both (a) and (b) above. (e) both (b) and (c) above.
ANSWER: d
16. The smaller the receptive fields in a region, the: (a) greater the density of receptors in the region. (b) greater the acuity in the region.
(c) more cortical space allotted for sensory reception from the region.
(d) both (a) and (b) above. (e) all of these answers.
ANSWER: e
17. Select the incorrect association.
(a) chemoreceptor/oxygen concentration. (b) mechanoreceptor/skeletal muscle stretch. (c) nociceptor/solute concentration.
(d) photoreceptor/light.
(e) thermoreceptor/heat and cold.
ANSWER: c
18. The slow pain pathway is activated by: (a) stimulation of mechanical or thermal nociceptors.
(b) stimulation of polymodal nociceptors. (c) release of bradykinin.
(d) both (a) and (c) above. (e) both (b) and (c) above.
ANSWER: e
19. Endorphins and enkephalins:
(a) are endogenous morphine-like substances. (b) are important in the body’s natural analgesic system.
(c) stimulate the release of substance P by binding with opiate receptors.
(d) both (a) and (b) above. (e) all of these answers.
ANSWER: d
20. Which is characteristic of fast pain? (a) poorly localized.
(b) occurs upon stimulation of polymodal nociceptors.
(d) persists for a long period of time. (e) none of these answers.
ANSWER: c
21. What is/are the role(s) of glutamate in the pain pathways?
(a) binds to AMPA receptors on dorsal horn cells. (b) results in hypersensitivity of damaged tissue. (c) causes P-substance release.
(d) both (a) and (b) above. (e) both (b) and (c) above.
ANSWER: d
22. Natural analgesia occurs:
(a) when endogenous opiates bind to P-substance. (b) when endogenous opiates bind to receptors on afferent pain fibers.
(c) when the periaqueaductal gray matter is stimulated.
(d) both (a) and (b) above. (e) both (b) and (c) above.
ANSWER: e
23. Which neuromodulator is not capable of binding to opiate receptors in the analgesic pathways? (a) bradykinin.
(b) dynorphin.
(c) endogenous opiates. (d) endorphins.
(e) enkephalins.
ANSWER: a
24. Select the incorrect statement about slow pain. (a) It is carried by large, myelinated A-delta fibers.
(b) It is poorly localized.
(c) It occurs by the stimulation of polymodal nociceptors.
(d) It occurs for a longer time than fast pain. (e) It produces a dull, aching, burning sensation.
ANSWER: a
25. Which of the following structures normally controls the amount of light entering the eye? (a) ciliary muscle.
(b) suspensory ligaments. (c) iris.
(d) cornea. (e) lens.
ANSWER: c
26. The circular muscle of the iris:
(a) contracts in response to bright light to produce pupillary constriction.
(b) is innervated by the parasympathetic nervous system.
(c) contracts to slacken the suspensory ligaments and increase the strength of the lens during accommodation.
(d) both (a) and (b) above. (e) all of these answers.
ANSWER: d
27. The retina:
(a) is the middle layer of the eye. (b) contains the photoreceptors.
(c) becomes specialized anteriorly to form the cornea.
(d) secretes the aqueous humor. (e) none of these answers.
ANSWER: b
28. The first structure to intercept light as it enters the eye is the:
(a) aqueous humor. (b) cornea.
(c) lens. (d) retina.
(e) vitreous humor.
ANSWER: b
29. Which of the following helps reduce internal reflection (scattering of light within the eye)? (a) sclera.
(b) choroid. (c) blind spot. (d) lens. (e) iris.
ANSWER: b
30. Which of the following structures contributes the most to the total refractive ability of the eye? (a) lens.
(b) cornea. (c) ciliary muscle. (d) retina. (e) iris.
ANSWER: b
(c) The ciliary muscle is relaxed for near vision. (d) The ciliary muscle is contracted for distant vision.
(e) None of these answers.
ANSWER: b
32. The lens of the eye: (a) has convex surfaces. (b) is stronger when it is flatter.
(c) contributes most extensively to the eye’s total refractive ability.
(d) two of these answers. (e) all of these answers.
ANSWER: a
33. During accommodation for near vision: (a) The ciliary muscle does not contract. (b) The lens becomes more convex.
(c) The suspensory ligaments become less taut. (d) Both (b) and (c) above.
(e) All of these answers.
ANSWER: e
34. As light passes from one medium to a medium of a different density:
(a) It is refracted.
(b) It bends at specific angles. (c) It changes wavelengths. (d) Both (a) and (b) above. (e) All of these answers.
ANSWER: d
35. In hyperopia:
(a) The eyeball is too short or the lens is too weak. (b) A near object is focused behind the retina, even with accommodation.
(c) A far source of light is focused ahead of the retina.
(d) Both (a) and (b) above. (e) Both (a) and (c) above.
ANSWER: d
36. Which of the following statements concerning myopia is correct?
(a) The curvature of the lens is uneven.
(b) A near source of light is focused on the retina without accommodation.
(c) A convex lens is used to correct the condition. (d) The images from the two eyes are not fused within the cortex.
(e) There is increased intraocular pressure.
ANSWER: b
37. The fovea:
(a) is located in the exact center of the retina. (b) contains a greater abundance of rods than cones.
(c) is the point on the retina at which the optic nerve leaves and blood vessels pass through. (d) both (a) and (b) above.
(e) all of these answers.
ANSWER: a
38. The blind spot:
(a) is the point on the retina at which the optic nerve leaves and blood vessels pass through. (b) contains no rods or cones.
(c) is in the exact center of the retina. (d) both (a) and (b) above.
(e) all of these answers.
ANSWER: d
39. The choroids:
(a) contains rods and cones. (b) is a fluid within the eye. (c) is also known as the blind spot. (d) is the middle layer of the eye. (e) refracts light rays.
ANSWER: d
40. Rhodopsin:
(a) is the photopigment found in the red cones. (b) consists of an opsin and retinene.
(c) is most highly concentrated in the fovea. (d) is slowly broken down in the absence of light. (e) contains a derivative of vitamin B12.
ANSWER: b
41. Cones:
(a) are most abundant in the periphery of the retina.
(b) are more numerous than rods. (c) have high sensitivity to light. (d) are responsible for color vision. (e) more than one of these.
ANSWER: d
42. Which of the following activities occurs in the presence of light within the phototransduction pathway?
(c) Bipolar cells produce graded potentials. (d) Sodium channels open in receptors. (e) None of these answers.
ANSWER: c
43. Which of the following statements concerning cones is incorrect?
(a) Cones are used for day vision. (b) Cones are very sensitive to light. (c) Cones exhibit high acuity.
(d) Cones are concentrated in the fovea. (e) Cones provide color vision.
ANSWER: b
44. Rods:
(a) are more sensitive to light than cones. (b) have low acuity.
(c) provide vision in shades of gray.
(d) have both low acuity and provide vision in shades of gray.
(e) all of these answers.
ANSWER: e
45. During dark adaptation:
(a) Photopigments are gradually regenerated. (b) Rhodopsin is rapidly broken down.
(c) The cones for gray vision are stimulated more than the cones for color vision.
(d) The sensitivity of the photoreceptors is reduced so that the image appears dim. (e) The bipolar cells are disinhibited.
ANSWER: a
46. In light adaptation:
(a) Rhodopsin levels increase in rods. (b) Rhodopsin levels decrease in rods. (c) Cones become active.
(d) Both (a) and (b) above. (e) Both (b) and (c) above.
ANSWER: e
47. Cones have higher acuity than rods because: (a) Cones respond more to dim light. (b) There are three types of cones. (c) There is little convergence in the cone pathways within the retina.
(d) There are more cones than rods.
(e) The photopigment in the cones breaks down more rapidly than the photopigment in rods.
ANSWER: c
48. Which of the following does not occur in a photoreceptor during exposure to light? (a) membrane hyperpolarization.
(b) closure of Na+ channels in the outer segment.
(c) increased transmitter release from the synaptic terminal.
(d) decrease in cyclic GMP in the outer segment. (e) closure of Ca2+ channels in the synaptic
terminal.
ANSWER: c
49. Which one of the following is an anterior specialization of the choroid layer? (a) aqueous humor.
(b) ciliary body. (c) cornea. (d) lens. (e) retina.
ANSWER: b
50. Color vision:
(a) is accomplished by rods at night and cones during the day.
(b) depends on the three cone types’ various ratios of stimulation in response to different wavelengths of light.
(c) is usually lost in vitamin A deficiency. (d) depends on activation of a specific cone for each visible color.
(e) is made possible by convergence within the cone pathways.
ANSWER: b
51. Vitamin A deficiency causes: (a) poor night vision. (b) poor color vision. (c) astigmatism. (d) presbyopia. (e) color blindness.
ANSWER: a
52. Presbyopia is characterized by: (a) the lack of a cone type.
(b) pronounced visual difficulty in the early teenage years.
(c) a reduction in accommodative ability as a result of a loss of lens elasticity.
(d) retinal damage.
(e) excessive refractive power in the lens system of the eye.
53. What condition is caused by uneven curvatures in the lens?
(a) astigmatism. (b) myopia. (c) presbyopia. (d) hyperopia.
(e) none of these answers.
ANSWER: a
54. The optic track:
(a) carries information from the lateral half of the retina on the same side and the medial half of the retina on the opposite side.
(b) carries information from the lateral halves of both
retinas.
(c) carries information from the medial halves of both retinas.
(d) carries information from the lateral half of the retina on the opposite side and the medial half of the retina on the same side.
(e) carries information from both the lateral and medial halves of the retina on the same side.
ANSWER: a
55. The middle layer of the retina contains: (a) bipolar neurons.
(b) convex cells. (c) ganglion cells. (d) hair cells. (e) rods and cones.
ANSWER: e
56. In the visual pathway:
(a) The fibers from the medial halves of both retinas cross at the optic chiasm.
(b) The optic nerve carries information from the lateral half of one retina and the medial half of the other retina.
(c) The optic nerve carries information from both the lateral half and the medial half of the retina of the same eye.
(d) Both (a) and (b) above. (e) Both (a) and (c) above.
ANSWER: e
57. Incoming visual information is relayed to the appropriate cortical tissue by the:
(a) colliculi.
(b) lateral geniculate nuclei. (c) the thalamus.
(d) both (a) and (b) above.
(e) both (b) and (c) above.
ANSWER: e
58. Which of the following is the proper sequence of retinal processing?
(a) rods and cones—ganglion cells—bipolar cells. (b) rods and cones—bipolar cells—ganglion cells. (c) ganglion cells—bipolar cells—rods and cones. (d) ganglion cells—rods and cones—bipolar cells. (e) bipolar cells—ganglion cells—rods and cones.
ANSWER: b
59. The three types of cones are: (a) black, red, and white. (b) blue, green, and red. (c) blue, green, and white. (d) green, orange, and yellow. (e) orange, yellow, and white.
ANSWER: b
60. Which structure(s) is/are associated with hearing? (a) ampulla.
(b) cochlea. (c) cupula. (d) cristae. (e) saccule.
ANSWER: b
61. The pitch of a sound:
(a) is determined by the frequency of vibrations of air molecules.
(b) depends on the amplitude of the waves. (c) is measured in units of decibels. (d) both (a) and (b) above.
(e) all of these answers.
ANSWER: a
62. The human ear is most sensitive to sound frequencies within the range of:
(a) 0–20,000 cycles per second. (b) 20–20,000 cycles per second. (c) 10–100,000 cycles per second. (d) 100–15,000 cycles per second. (e) 1,000–4,000 cycles per second.
ANSWER: e
63. All of the following are true statements about sound waves except:
(b) They gradually dissipate as they travel from the original sound source.
(c) The human ear can detect sound waves between 20 and 20,000 cycles per second. (d) The average human ear is most sensitive to sound waves with frequencies between 5,000 and 10,000 cycles per second.
(e) They consist of alternating regions of air compression and rarefaction.
ANSWER: d
64. The tympanic membrane:
(a) vibrates when struck by sound waves. (b) contains the organ of Corti.
(c) produces ear wax. (d) is connected to the stapes. (e) none of these answers.
ANSWER: a
65. The vibrational stimulus normally passes through the middle ear ossicles in the order:
(a) incus to the malleus to the stapes. (b) incus to the stapes to the incus. (c) malleus to the incus to the stapes. (d) malleus to the stapes to the incus. (e) stapes to the malleus to the incus.
ANSWER: c
66. The ossicular system of the ear:
(a) serves to keep the pressure on the two sides of the tympanic membrane equal.
(b) increases the pressure of vibration as it transfers the sound wave from air in the outer ear to fluid in the inner ear.
(c) assists in determining whether a sound comes from the front or rear.
(d) is part of the vestibular apparatus. (e) is in direct contact with the tympanic membrane and the round window.
ANSWER: b
67. Transmission of sound through the middle ear results in:
(a) amplification of the pressure vibrations. (b) stimulation of middle ear receptor cells. (c) opening of the eustachian tube.
(d) increased firing rate in sensory axons associated with the tympanic membrane. (e) none of these answers.
ANSWER: a
68. Actual conversion of sound vibrations to nerve impulses occurs in the:
(a) eardrum. (b) ossicular system. (c) eustachian tube. (d) cochlea. (e) oval window.
ANSWER: d
69. Which one of the following is not involved in sending the vibrational signal to the inner ear? (a) external auditory meatus.
(b) eustachian tube. (c) malleus. (d) stapes. (e) tympanum.
ANSWER: b
70. The hair cells for hearing are located in the: (a) cochlea.
(b) eustachian tube. (c) saccule. (d) utricle. (e) vestibule.
ANSWER: a
71. High- and low-frequency sounds are discriminated chiefly by:
(a) low frequencies producing stronger vibrations. (b) high frequencies producing larger action potentials.
(c) the middle ear bones vibrating more vigorously for low frequencies.
(d) low frequencies deflecting the basilar membrane at a greater distance from the oval window.
(e) low frequencies setting up fluid vibrations in the perilymph.
ANSWER: d
72. Select the structure that is not found inside the cochlear duct.
(a) basilar membrane. (b) endolymph. (c) oval window. (d) organ of Corti. (e) tectorial membrane.
ANSWER: c
(b) transfers the sound wave from the middle ear to the inner ear.
(c) is reflexively tightened in response to loud sounds to diminish transmission of these sounds to the inner ear.
(d) both attaches to the stapes and transfers the sound wave from the middle ear to the inner ear. (e) all of these answers.
ANSWER: d
74. In response to movement of the oval window: (a) Pressure waves occur in the scala vestibuli. (b) A portion of the basilar membrane vibrates. (c) Certain hair cell receptors in the organ of Corti become excited.
(d) The round window is displaced. (e) All of these answers.
ANSWER: e
75. In which structure do sound waves first pass? (a) cochlear duct.
(b) scala media. (c) scala tympani. (d) scala vestibuli. (e) helicotrema.
ANSWER: d
76. Fluid movement in the cochlea causes: (a) displacement of the round window, which dissipates pressure.
(b) deflection of the basilar membrane.
(c) the hairs of the receptor cells of the organ of Corti to be bent as they are moved in relation to the tectorial membrane.
(d) two of these answers. (e) all of these answers.
ANSWER: e
77. Deflection of the basilar membrane:
(a) activates the receptors of the organ of Corti. (b) occurs in response to fluid movements in the cochlea.
(c) results from displacement of the round window.
(d) both activates the sound receptors of the organ of Corti and occurs in response to fluid
movements in the cochlea are correct. (e) all of these answers.
ANSWER: d
78. Which type of sensory input is not integrated into the sense of equilibrium?
(a) cutaneous. (b) proprioceptive. (c) vestibular. (d) visual. (e) visceral.
ANSWER: e
79. Which of the following abnormalities could give rise to sensorineural deafness?
(a) rupture of the tympanic membrane. (b) disease or injury in the organ of Corti. (c) restriction of ossicular movement because of adhesions between the bones.
(d) damage to the occipital lobes of the cortex. (e) presbyopia.
ANSWER: b
80. The semicircular canals:
(a) detect the position of the head relative to gravity.
(b) detect rotational or angular acceleration of the head.
(c) contain otoliths. (d) both (a) and (c) above. (e) both (b) and (c) above.
ANSWER: b
81. Select the incorrect association. (a) cochlear duct/endolymph. (b) malleus/inner ear. (c) organ of Corti/hair cells. (d) scala tympani/perilymph. (e) scala vestibuli/perilymph.
ANSWER: b
82. The utricle is: (a) an otolith organ.
(b) activated when a person bends the head to look down at the ground.
(c) activated when a person starts to walk. (d) two of these answers.
(e) all of these answers.
ANSWER: e
83. Vestibular information is important for all of the following except:
(a) hearing.
(d) perception of motion and orientation. (e) none of these answers.
ANSWER: a
84. The auditory cortex is on the _________ lobe of the cerebral cortex.
(a) frontal. (b) occipital. (c) parietal. (d) prefrontal. (e) temporal.
ANSWER: e
85. Taste:
(a) discrimination depends on the ratio of stimulation of the taste buds, which have a variation in relative sensitivity.
(b) buds are stimulated only by chemicals in solution.
(c) discrimination does not go beyond
distinguishing between the four primary tastes— sweet, sour, salty, and bitter.
(d) both (a) and (b) above. (e) all of these answers.
ANSWER: d
86. Sour taste represents stimuli caused by: (a) acids.
(b) salts. (c) bases. (d) sugars. (e) alkaloids.
ANSWER: a
87. Binding of scent signals to olfactory receptors: (a) activates G proteins.
(b) results in cAMP production. (c) opens sodium channels. (d) both (a) and (b) above. (e) all of these answers.
ANSWER:
88. Olfactory receptors:
(a) are specialized endings of afferent neurons, not separate cells.
(b) when stimulated send impulses both to the limbic system for coordination between smell and behavior and to the thalamus and cortex for perception of smell.
(c) are replaced about every two months. (d) both (a) and (b) above.
(e) all of these answers.
ANSWER: e
89. The structure associated with pheromonal reception is:
(a) the nasal organ. (b) the olfactory mucosa. (c) papillae.
(d) taste buds.
(e) vomeronasal organ.
ANSWER: e
True/False
90. Sensory information from the skeletal muscles enters the central nervous system by visceral efferent neurons.
ANSWER: False
91. Receptors transduce one form of energy into electrical energy.
ANSWER: True
92. Any stimulus can excite any excitable tissue.
ANSWER: False
93. The term adequate stimulus refers to the intensity of a stimulus developing above a threshold value.
ANSWER: False
94. Receptor potentials can be graded, with a stronger stimulus resulting in a larger receptor potential.
ANSWER: True
95. Osmoreceptors are sensitive to changing solute concentrations.
ANSWER: True
96. Receptors can respond only to electrical stimulation.
ANSWER: False
97. Proprioception is the awareness of the body’s position in space.
98. A receptor cell initially develops a generator potential by the influx of potassium.
ANSWER: False
99. The stronger the stimulus, the greater the frequency of action potentials generated and propagated in the afferent neuron.
ANSWER: True
100.The identical nerve pathway conveys information regarding pressure and temperature sensation of the thumb.
ANSWER: False
101.Pain may be elicited by thermal or chemical stimuli.
ANSWER: True
102.Phasic receptors are rapidly adapting receptors.
ANSWER: True
103.Activation of a sensory pathway at any point gives rise to the same sensation that would be produced by stimulation of the receptors in the body part itself.
ANSWER: True
104.Through lateral inhibition, a more intensely activated receptor pathway halts transmission of impulses in surrounding, less intensely stimulated pathways.
ANSWER: True
105.All nociceptors are naked nerve endings.
ANSWER: True
106.There are naturally occurring morphine-like substances in the brain.
ANSWER: True
107.Prostaglandins suppress the sensitivity of nociceptors.
ANSWER: False
108.Descending analgesic pathways are believed to suppress transmission in the pain pathways as they enter the spinal cord by blocking the release of substance P.
ANSWER: True
109.The Pacinian corpuscle is mainly sensitive to temperature changes.
ANSWER: False
110.Second- and third-order sensory neurons synapse in the thalamus.
ANSWER: True
111.Short-wave lengths of light within the visible spectrum are sensed as violet or blue.
ANSWER: True
112.Light rays travel faster through water or glass than through air.
ANSWER: False
113.Unmyelinated C fibers send impulses for slow pain pathways.
ANSWER: True
114.Light is the only stimulus capable of stimulating the photoreceptors of the eye.
ANSWER: False
115.The circular muscle of the iris contracts in response to dim light.
ANSWER: False
116.Contraction of the radial muscle of the iris produces a dilation of the iris.
ANSWER: True
117.The sclera is the most internal layer of the eye.
ANSWER: False
118.A convex lens converges light rays or brings them closer together.
119.The greater the curvature of a lens, the greater its ability to refract light rays.
ANSWER: True
120.The fovea is the point on the retina where the optic nerve leaves.
ANSWER: False
121.The curvature of the lens must be adjusted to enable the eye to focus both near and far sources on the retina.
ANSWER: True
122.Light rays passing through a concave lens undergo convergence.
ANSWER: False
123.The term cataract refers to the condition in which the lens becomes stiff and loses its elasticity.
ANSWER: False
124.Relaxation of the ciliary muscle changes the cornea into a flattened shape.
ANSWER: False
125.The image on the retina is reversed upside down and backwards because of bending of light rays.
ANSWER: True
126.A concave lens is used to correct for a myopic eye.
ANSWER: True
127.Retinene is found in the rods but not the cones.
ANSWER: False
128.Rods produce vision in shades of gray.
ANSWER: True
129.Vision in bright light is chiefly due to cone activation.
ANSWER: True
130.Cone photoreceptors provide high visual acuity.
ANSWER: True
131.When an individual sees pure red, only the red cones are stimulated.
ANSWER: False
132.In the retina, photoreceptor cells do not synapse with bipolar cells.
ANSWER: False
133.Light must pass through several layers of retinal cells before reaching rods and cones.
ANSWER: True
134.Color blindness may be caused by Vitamin A deficiency.
ANSWER: False
135.Night blindness is due to a deficiency of Vitamin C.
ANSWER: False
136.Each cone contains three different photopigments for selectively responding to red, blue, or green wavelengths of light.
ANSWER: False
137.Cones are more abundant than rods through the entire retina.
ANSWER: False
138.A photoreceptor generates action potentials when its photopigment is activated.
ANSWER: False
139.Depth perception comes about in large part because of binocular vision.
ANSWER: True
140.At the optic chiasm, the fibers in the lateral half of each optic nerve cross over.
141.Axons from retinal ganglion cells form the optic nerve.
ANSWER: True
142.Diplopia is another name for double vision.
ANSWER: True
143.Each region of the auditory cortex becomes excited only in response to a specific tone detected by a selected portion of the basilar membrane.
ANSWER: True
144.Photoreceptors are depolarized in the absence of stimulation (i.e., in the dark) and hyperpolarized when stimulated (i.e., when exposed to light).
ANSWER: True
145.The greatest density of rods is found in the fovea of the macula lutea.
ANSWER: False
146.Accommodation permits near vision.
ANSWER: True
147.In hyperopia the far source is focused on the retina with accommodation and the near source is focused behind the retina.
ANSWER: True
148.Short wavelengths of light are perceived in the red-orange color range.
ANSWER: False
149.The external eye muscles contract to change the shape of the lens.
ANSWER: False
150.Photoreceptors, bipolar cells, and ganglion cells all display action potentials.
ANSWER: False
151.Each half of the visual cortex receives information from the opposite half of the visual field as detected by both eyes.
ANSWER: True
152.Binocular vision enhances depth perception.
ANSWER: True
153.The visual message detected by the retina is transmitted intact to the visual cortex.
ANSWER: False
154.Unlike the visual pathways, auditory signals from each ear are transmitted to both hemispheres.
ANSWER: True
155.The amplitude of sound waves is interpreted as the pitch of the sound.
ANSWER: False
156.The inner ear is involved only with hearing.
ANSWER: False
157.The incus is a structure of the middle ear.
ANSWER: True
158.The cochlea is primarily concerned with equilibrium.
ANSWER: False
159.The stapes is attached to the round window.
ANSWER: False
160.The function of the Eustachian tube is to provide a drainage path for the fluid in the middle ear.
ANSWER: False
161.The helicotrema is located beyond the tip of the cochlear duct.
ANSWER: True
162.The ossicular system transmits the vibrations of the tympanic membrane to the oval window, movement of which sets up pressure waves in the cochlear fluid.
163.In response to high frequency sounds, the segment of the basilar membrane closer to the oval window vibrates maximally.
ANSWER: True
164.Exposure to very loud noises can result in partial conductive deafness.
ANSWER: False
165.Hearing aids are more beneficial in conductive deafness than in sensorineural deafness.
ANSWER: True
166.The semicircular canals are activated as the head starts to rotate, but cease responding if the head movement continues at the same rate in the same direction.
ANSWER: True
167. The utricle detects changes in head position away from horizontally and vertically directed linear acceleration and deceleration.
ANSWER: True
168.The vestibular nuclei provide output important in maintaining balance and posture.
ANSWER: True
169.Mechanical deformation of the hairs of hair cells in the inner ear always results in depolarization of the hair cell synaptic terminal.
ANSWER: False
170.Taste buds are chemoreceptors.
ANSWER: True
171.The cortical gustatory area is located adjacent to the “tongue” region of the somatosensory cortex.
ANSWER: True
172.Sour taste is caused by the hydrogen ions from acids.
ANSWER: True
173.Normal breathing patterns directly bring odoriferous molecules in contact with the olfactory mucosa.
ANSWER: False
174.The receptors for smell are located in the upper nasal cavity out of the normal path of air currents.
ANSWER: True
175.Visual and hearing receptors are irreplaceable, but taste and olfactory receptors are continuously renewed.
ANSWER: True
176.Rapid reduction in sensitivity to a new odor results from rapid adaptation of the olfactory receptors.
ANSWER: False
177.The olfactory mucosa contains enzymes that remove odoriferous molecules so that the sensation of smell doesn’t linger after the source of the odor is removed.
ANSWER: True
178.The primary olfactory cortex is on the temporal lobe.
ANSWER: True
Fill-in-the-Blank
179.__________ is our conscious interpretation of the external world as created by the brain from a pattern of nerve impulses delivered to it from sensory receptors.
ANSWER: perception
180.An incoming pathway for subconscious information derived from the internal viscera is called a(n) __________, whereas an incoming pathway for information propagated to the conscious levels of the brain is called a(n) __________.
181.A generator potential in a receptor begins with the influx of ________ ions into the cell.
ANSWER: sodium
182.By ________, a stimulus of the same intensity does not elicit a receptor potential of the same magnitude.
ANSWER: adaptation
183.Each sensory neuron responds to stimulus information within its __________, which is a circumscribed region of the skin surface surrounding it.
ANSWER: receptive field
184. _________ are the receptors that display the least amount of adaptation.
ANSWER: nociceptors
185.__________, a neurotransmitter unique to pain fibers, is released from afferent pain terminals.
ANSWER: Substance P
186.The intensity of a stimulus is coded by the _________ of the action potentials sent along the related afferent neuron.
ANSWER: frequency
187._________ attach the lens to the ciliary body.
ANSWER: suspensory ligaments
188.Light is a form of electromagnetic radiation composed of particle-like individual packets of energy called _________ that travel in wavelike fashion.
ANSWER: photons
189.The __________ is the layer of the eye that contains the photoreceptor cells.
ANSWER: retina
190.The iris consists of layers of________ and ________ smooth muscle fibers.
ANSWER: circular, radial
191.The two major components of the ciliary body are the __________, which regulates the strength of the lens, and a capillary network that produces __________.
ANSWER: ciliary muscle, aqueous humor
192.The point of the retina with the most distinct vision is the __________.
ANSWER: fovea
193.__________ is the bending of light rays as they pass from one medium to another.
ANSWER: refraction
194.The eye structure with the greatest refractive ability is the __________.
ANSWER: cornea
195.The refractive structure of the eye that has the ability to change its strength is the __________.
ANSWER: lens
196.Myopia is another name for ________.
ANSWER: nearsightedness
197.The ________ is the region of the retina where rods and cones are absent.
ANSWER: blind spot or optic disk
198.Rods and cones have a G protein called ________.
ANSWER: transducin
199.__________ are traveling vibrations of air that consist of alternating with regions of low pressure caused by rarefaction of the molecules.
ANSWER: sound waves
200.Night blindness develops from a deficiency of vitamin ________.
ANSWER: A
201.The left cerebral cortex receives information from the ________ half of each visual field.
202.The lateral geniculate nucleus is located in the ________ of the brain.
ANSWER: thalamus
203.The ______ is the ossicle attached to the oval window.
ANSWER: stapes
204.______ discrimination depends of the region of the basilar membrane that vibrates.
ANSWER: pitch
205.Moving air through the eustachian tube equalizes air pressure on the ________.
ANSWER: tympanum
206.Glucose interacts with ________ receptor binding sites on the surface of the tongue.
ANSWER: sweet
207. The rods and cones synapse with __________ cells which in turn synapse with ganglion cells before entering the optic nerve.
ANSWER: bipolar
Sequencing
208.Indicate the proper sequence of involvement in the visual pathway by writing the appropriate letter in the blank, using the answer code below.
(a) bipolar neurons (b) optic nerve
(c) lateral geniculate nucleus (d) rods and cones
(e) visual cortex (f) optic tracts (g) ganglion cells (h) optic radiations
_____ First _____ Second _____ Third _____ Fourth _____ Fifth _____ Sixth _____ Seventh _____ Eighth
ANSWERS: d, a, g, b, f, c, h, e
Statement Completion
Complete the statements by circling the correct response.
209.For near vision, the ciliary muscle (contracts or relaxes) so that the suspensory ligaments become (taut or slack). This allows the lens to (flatten or round up), which (increases or decreases) the strength of the lens.
ANSWERS: contracts, slack, round up, increases
210.When light of suitable wavelength strikes a photoreceptor, the photopigment (absorbs or reflects) the light, causing the photopigment to (dissociate or regenerate). This photopigment transformation acts through a second messenger system to cause Na+ channels in the outer segment
to (open or close). Subsequently, the
photoreceptor (depolarizes or hyperpolarizes), which results in a(n) (increase or decrease) in release of an (excitatory or inhibitory) transmitter from its synaptic terminal.
ANSWERS: absorbs, dissociate, close, hyperpolarizes, decrease, inhibitory
Matching
211.Match the receptor below to its function. (a) tonic receptor
(b) phasic receptor
(c) specialized receptor ending of afferent neuron (d) separate cell serving as a receptor
_____ generates action potentials in afferent neuron by opening voltage-gated Na+ channels.
_____ generates action potentials in afferent neuron by opening messenger-gated channels. _____ provides continuous information about the
stimuli being monitored.
_____ provides information about changes in the energy form being monitored.
212.Indicate the properties associated with each type of nociceptor by using the answer code below (more than one answer may apply):
(a) mechanical nociceptor (b) thermal nociceptor (c) polymodal nociceptor
_____ responds to cutting, crushing, pinching. _____ responds to irritating chemicals. _____ responds to temperature extremes. _____ transmits its signals via A-delta fibers. _____ transmits its signals via C fibers. _____ activates slow pain pathway. _____ activates fast pain pathway.
ANSWERS: a, c, b, a and b, c, c, a and b
213.Indicate which of the following regions are part of ascending pain pathways, descending analgesic pathways, or both.
(a) part of ascending pain pathway (b) part of descending analgesic pathway (c) participates in both pain and analgesic pathways
_____ periaqueaductal gray area _____ thalamus
_____ reticular formation
ANSWERS: b, a, c
214.Indicate the properties of rods and cones using the following answer code:
(a) rods (b) cones
(c) both rods and cones
_____ used for day vision _____ used for night vision _____ confer color vision
_____ confer vision in shades of gray _____ high acuity
_____ low acuity
_____ contain opsin and retinene _____ much convergence in pathway _____ little convergence in pathways
_____ three different types as a result of difference in photopigment content
ANSWERS: b, a, b, a, b, a, c, a, b, b
215.Match the following eye disorder with its description.
(a) color blindness (b) night blindness (c) glaucoma (d) hyperopia (f) presbyopia (e) diplopia (g) myopia lens (h) cataract (i) astigmatism
_____ eyeball too long _____ eyeball too short
_____ corrected by cylindrical lens _____ corrected by concave lens _____ corrected by convex _____ corneal surface uneven
_____ images from two eyes not fused within cortex _____ increased intraocular pressure
_____ opaque lens _____ stiffened lens _____ vitamin A deficiency _____ lack of a cone type
ANSWERS: g, d, i, g, d, i, e, c, h, f, b, a
216.Indicate the characteristics associated with each part of the ear using the answer code below (more than one answer may apply):
(a) external ear (b) middle ear
(c) cochlea in the inner ear
(d) semicircular canal in the inner ear (e) utricle and saccule in the inner ear
_____ is air-filled. _____ is fluid-filled.
_____ contains receptive hair cells. _____ is concerned with hearing.
_____ is concerned with sense of equilibrium. _____ contains the tympanic membrane, which
vibrates in synchrony with sound waves. _____ contains the ossicular system, which
contributes to the amplification of the sound wave.
_____ containing. a cupula, which sways in the direction of endolymph movement, bending the embedded hair cells
_____ provides information about the position of the head relative to gravity.
_____ detects rotational acceleration or deceleration of the head.
_____ contains the organ of Corti whose hair cells are bent during vibration of the basilar membrane.
_____ is connected with the throat via the eustachian tube.
_____ provides information useful for keeping the eyes focused on a fixed object even when the head is moving.
_____ is part of the vestibular apparatus. _____ consists of three elongated spiral
compartments.
_____ components aligned in three different planes all perpendicular to each other.
ANSWERS: a and b; c, d, and e; c, d, and e; c; d and e; b; b; d; e; d; e; c; b; d and e; d and e; d; d
217.Match the following term with its description. (a) timbre (quality)
(b) pitch (tone)
(c) intensity of a sound wave (loudness)
_____ the frequency of sound waves. _____ dependent on the overtones.
_____ dependent on the amplitude of the sound wave.
_____ measured in cycles per second. _____ measured in decibels.
ANSWERS: b, a, c, b, c
218.Match the following receptors to their locations. (a) chemoreceptors
(b) mechanoreceptors (c) photoreceptors
_____ receptors in retina _____ receptors in cochlea _____ receptors in otolith organs _____ receptors in semicircular canals _____ receptors in taste buds
_____ receptors in olfactory mucosa
ANSWERS: c, b, b, b, a, a
219.Match the following terms with their descriptions. (a) alkaloid
(b) acid
(c) anything with chemical configuration similar to glucose
(d) NaCl
_____ tastes salty _____ tastes sour _____ tastes bitter _____ tastes sweet
ANSWERS: d, b, a, c
Essay Questions
1. Describe how sensory adaptation occurs.
2. Describe the phototransduction process.
3. What are the various roles of secondary messenger systems in sensory pathways?
4. Describe the conduction of sound energy and its subsequent transduction into neural stimuli.
