Sensory Transduction Chapter.21 Test Bank Answers

Chapter 21: Sensory Transduction

Test Bank

Type: multiple choice question

Title: Chapter 21 Question 01

1. Long receptors are much better able to adapt to different stimulus intensities mostly because

Feedback: Subhead: Stimulus Coding by Mechanoreceptors

Learning Objective: Describe how short and long receptors differ in morphology and function.

Bloom’s Level: 4. Analyzing

a. their axons are much longer.

b. their somas are much larger.

c. both presynaptic and postsynaptic membranes are capable of changing the shape and size of the synapse.

d. long receptors usually release more neurotransmitter than short ones do.

e. electrical potentials travel faster in long receptors than in short receptors.

Type: multiple choice question

Title: Chapter 21 Question 02

2. Spread of electrical potentials throughout the membrane of long receptors is arguably more reliable than in short receptors because

Feedback: Subhead: Stimulus Coding by Mechanoreceptors

Learning Objective: Describe how short and long receptors differ in morphology and function.

Bloom’s Level: 4. Analyzing

a. long receptors fire action potentials, which do not decay with distance.

b. long receptors’ distance is much longer than that in short receptors.

c. short receptors fire only sub-threshold potentials, each of which is slower than action potentials are.

d. short receptors rely on the disturbance of cilia, which can easily be damaged.

e. short receptors rely on extensions, such as cilia (hair cells) or photoreceptors (retinal layer of cells) to transfer the potential.

Type: multiple choice question

Title: Chapter 21 Question 03

3. Which would serve to demonstrate the workings of the Weber–Fechner Relationship?

Feedback: Subhead: Stimulus Coding by Mechanoreceptors

Learning Objective: Explain what the Weber–Fechner relationship is and what its consequences are for the perception of stimuli.

Bloom’s Level: 3. Applying

a. Cover one eye in dim light and then shine a light into the uncovered eye. Observe the pupillary reaction of the uncovered eye.

b. Testing for color blindness—whether one can discern among the different primary colors.

c. Testing hearing whether one can distinguish among different pitches or tones.

d. Without looking, another person places successively heavier weights, starting with a barely perceptible weight, on your outstretched hand to determine the sensitivity or the point at which a difference is perceived.

e. While looking, another person places successively heavier weights, starting with barely a perceptible weight, on your outstretched hand to determine the sensitivity or the point at which a difference is perceived.

Type: multiple choice question

Title: Chapter 21 Question 04

4. Which is true about the Weber–Fechner Law?

Feedback: Subhead: Stimulus Coding by Mechanoreceptors

Learning Objective: Explain what the Weber–Fechner relationship is and what its consequences are for the perception of stimuli.

Bloom’s Level: 2. Understanding

a. It is a ratio of the just-noticeable difference (JND)/standard stimulus.

b. Is applicable to all sensory modalities.

c. Strength of the sensation increases as the logarithm of stimulus intensity.

d. It is applicable across the entire range of a stimulus intensity: from the JND to the most intense.

e. It is applicable to only subtle JND values of stimulus intensity.

Type: multiple choice question

Title: Chapter 21 Question 05

5. Which is an advantage to using the crayfish stretch receptor to analyze stimulus coding?

Feedback: Subhead: Stimulus Coding by Mechanoreceptors

Learning Objective: Give two reasons why the crayfish stretch receptor is such a useful model for mechanosensory investigations.

Bloom’s Level: 1. Remembering

a. The soma of the stretch receptor is integrated within the ganglion.

b. The soma of the stretch receptor is separate from the ganglion.

c. The soma of the stretch receptor is durable and can be used many times over after multiple procedures.

d. It has a low resting membrane potential, making it highly sensitive to any stimulus.

e. It has a large axon, into which implanting electrodes is easy.

Type: multiple choice question

Title: Chapter 21 Question 06

6. Which is a (small) disadvantage to using the crayfish stretch receptor to analyze stimulus coding?

Feedback: Subhead: Stimulus Coding by Mechanoreceptors

Learning Objective: Give two reasons why the crayfish stretch receptor is such a useful model for mechanosensory investigations.

Bloom’s Level: 4. Analyzing

a. The experiments are highly specialized and difficult to set up.

b. Crayfish axons are tiny and difficult into which to insert microelectrodes.

c. The CNS regulates receptor sensitivity, thereby confounding any kind of Weber–Fechner type of stimulus coding.

d. The stretch receptor soma is isolated from any ganglion.

e. Inhibitory innervation predominate over that of excitatory innervation.

Type: multiple choice question

Title: Chapter 21 Question 07

7. Which is true about adaptation?

Feedback: Subhead: Stimulus Coding by Mechanoreceptors

Learning Objective: Define adaptation.

Bloom’s Level’s 1. Remembering

a. Stimulus leads to strong response followed by decreasing response.

b. Stimulus leads to weak response followed by an increasingly stronger response.

c. Stimulus leads to intermittent response throughout.

d. Stimulus leads to a strong response followed by intermittent responses.

e. Stimulus leads to a weak response followed by intermittent response.

Type: multiple choice question

Title: Chapter 21 Question 08

8. Which is probably not an example of adaptation?

Feedback: Subhead: Stimulus Coding by Mechanoreceptors

Learning Objective: Define adaptation.

Bloom’s Level’s 3. Applying

a. Feeling the clothing against your skin as you get dressed but then after a few seconds no longer feeling it

b. At first disliking the taste of a food that is novel to you, but then after a while acquiring a taste for it

c. Suffering severe intractable pain because of cancer and its treatment

d. Entering a dimly lit room from the outside bright sunlight, after which your vision improves

e. Attending a loud concert where you cannot hear anything except the noise coming from the stage

Type: multiple choice question

Title: Chapter 21 Question 09

9. Which is an example of rapidly adapting receptors responding?

Feedback: Subhead: Stimulus Coding by Mechanoreceptors

Learning Objective: Differentiate between rapidly adapting receptors and slowly adapting receptors.

Bloom’s Level’s 3. Applying

a. Stepping from a warm room to outside in the snow where you are shivering for as long as you are outside in the cold

b. Putting on and wearing a pair of shoes that are far too tight for you

c. Entering a landfill where you smell all kinds of offensive odors

d. Getting dressed, feeling the flutter of clothing against your skin

e. Giving your eyes time to adjust to sudden changes in brightness

Type: multiple choice question

Title: Chapter 21 Question 10

10. Experimentally, to differentiate rapidly adapting receptors from slowly adapting receptors would be to determine

Feedback: Subhead: Stimulus Coding by Mechanoreceptors

Learning Objective: Differentiate between rapidly adapting receptors and slowly adapting receptors.

Bloom’s Level’s 4. Analyzing

a. the peak of the electrical potentials in the response.

b. if the preparation is responding by firing action potentials or excitatory/inhibitory postsynaptic potentials.

c. the relative frequency and pattern (start strong, end weak) of action potentials for the duration of the stimulus.

d. the relative frequency and pattern of excitatory/inhibitory postsynaptic potentials for the duration of the stimulus.

e. whether action potentials are firing when the stimulus starts and then cease when the stimulus ends.

Type: multiple choice question

Title: Chapter 21 Question 11

11. The authors mention that it is unusual for the muscle spindle to release glutamate (or any neurotransmitter, for that matter) because sensory nerve endings usually receive input rather than send them out. How might glutamate change the sensitivity of the stretch receptors?

Feedback: Subhead: Stimulus Coding by Mechanoreceptors

Learning Objective: Describe the basic scheme of mammalian muscle spindle innervation.

Bloom’s Level: 4. Analyzing

a. By modulating the density of the alpha motor neurons synapsing in the neuromuscular junctions

b. By modulating the entry of calcium into the muscle during stretch

c. By modulating the sensitivity of the Golgi tendon organs

d. By changing the density of calcium-activated potassium channels

e. By modulating the density of spiral endings of Group Ia and II afferents around the nuclear chain fibers

Type: multiple choice question

Title: Chapter 21 Question 12

12. How are nuclear bag fibers and nuclear chain fibers similar?

Feedback: Subhead: Stimulus Coding by Mechanoreceptors

Learning Objective: Describe the basic scheme of mammalian muscle spindle innervation.

Bloom’s Level: 2. Understanding

a. Multinucleation

b. The arrangement of nuclei

c. Sensitivity to changes in muscle length

d. Sensitivity to how fast muscle length changes

e. The type of afferents they use

Type: multiple choice question

Title: Chapter 21 Question 13

13. What can you reasonably deduce about why the Group Ia afferents conduct faster than the Group II afferents?

Feedback: Subhead: Stimulus Coding by Mechanoreceptors

Learning Objective: Discuss the functional differences between Group Ia and Group II afferent fibers.

Bloom’s Level: 3. Applying

a. Group Ia afferents spiral around both nuclear bag and nuclear chain fibers, whereas Group II spiral around only nuclear chain fibers.

b. Group II afferents spiral around both nuclear bag and nuclear chain fibers, whereas Group Ia spiral around only nuclear chain fibers.

c. Group Ia spirals comprise primary endings, whereas Group II spirals comprise secondary endings.

d. Group Ia afferents have larger diameters and are more heavily myelinated than Group II afferents.

e. Group II afferents have larger diameters and are more heavily myelinated than Group Ia afferents.

Type: multiple choice question

Title: Chapter 21 Question 14

14. If the spindle length suddenly increases, which will respond the most vigorously?

Feedback: Subhead: Stimulus Coding by Mechanoreceptors

Learning Objective: Discuss the functional differences between Group Ia and Group II afferent fibers.

Level: 3. Applying

a. Group Ia afferents

b. Group II afferents

c. Both group Ia and II afferents

d. Gamma motoneurons

e. Alpha motoneurons

Type: multiple choice question

Title: Chapter 21 Question 15

15. What might be the advantage of both the cochlea and semicircular canals being curved?

Feedback: Subhead: Transduction by Mechanosensory Cells

Learning Objective: Name the two structures in the inner ear where mechanosensitive hair cells are found.

Bloom’s Level: 3. Applying

a. Hair cell receptor sensitivities are best suited to curved structures.

b. Curved structures have more surface area than structures of other shapes would within the confines of the inner ear.

c. Endolymph flow is more dynamic (and the least static) in curved structures.

d. Curved structures are most susceptible to vibrational disturbances of sound or angular rotation.

e. Curved structures are the least susceptible to debris and other particulate matter from interfering with their functions.

Type: multiple choice question

Title: Chapter 21 Question 16

16. In humans, the acoustic range is 20–20,000 Hz. According to the Weber–Fechner Law, how many orders of magnitude does this represent?

Feedback: Subhead: Transduction by Mechanosensory Cells

Learning Objective: Name the two structures in the inner ear where mechanosensitive hair cells are found.

Bloom’s Level: 3. Applying

a. 1

b. 2

c. 3

d. 4

e. 5

Type: multiple choice question

Title: Chapter 21 Question 17

17. The hair on hair cell receptors are composed of

Feedback: Subhead: Transduction by Mechanosensory Cells

Learning Objective: Describe the basic structure and functional specializations of hair cell receptors.

Bloom’s Level: 1. Remembering

a. actin polymers.

b. tubulin polymers.

c. keratin.

d. a mixture of actin and lipids.

e. a mixture of actin and keratin.

Type: multiple choice question

Title: Chapter 21 Question 18

18. Depolarization of hair cell receptors is caused by

Feedback: Subhead: Transduction by Mechanosensory Cells

Learning Objective: Describe the basic structure and functional specializations of hair cell receptors.

Bloom’s Level: 3. Applying

a. sodium entry.

b. potassium entry.

c. calcium entry.

d. chloride exit.

e. potassium entry and chloride exit.

Type: multiple choice question

Title: Chapter 21 Question 19

19. When recording mechanotransduction in hair cells, which would affect the magnitude of the response?

Feedback: Subhead: Transduction by Hair Bundle Deflection

Learning Objective: Outline the experimental setup used to record mechanotransduction in hair cells.

Bloom’s Level: 2. Understanding

a. The magnitude of the deflection of the hairs by the glass fiber rod

b. The speed at which the glass fiber rod deflects the hairs

c. The salinity of the preparation

d. The angle at which the glass fiber rod deflects the hairs

e. Whether the deflection of the hairs was constant or intermittent

Type: multiple choice question

Title: Chapter 21 Question 20

20. If a 1-nm deflection can produce a 0.2 mV voltage change in the hair cell, how many nm must the hair cell be deflected to move the resting membrane potential of -70 mV to a threshold of -50 mV?

Feedback: Subhead: Transduction by Hair Bundle Deflection

Learning Objective: Outline the experimental setup used to record mechanotransduction in hair cells.

Bloom’s Level: 3. Applying

a. 10 nm

b. 50 nm

c. 100 nm

d. 200 nm

e. 500 nm

Type: multiple choice question

Title: Chapter 21 Question 21

21. Tip links are likely arranged only along the axis of mechanical stimulation because this

Feedback: Subhead: Transduction by Hair Bundle Deflection

Learning Objective: Explain how tip links are involved in mechanotransduction.

Bloom’s Level: 3. Applying

a. limits the movement and increases the sensitivity of the stereocilia.

b. decreases the distance the stereocilia must be deflected.

c. provides maximal activation of ion-gated channels for rapid depolarization.

d. enables the stereocilia to maximally respond to even the tiniest deflection.

e. lowers the threshold for firing action potentials.

Type: multiple choice question

Title: Chapter 21 Question 22

22. Breaking off the tip link abolishes mechanotransduction because

Feedback: Subhead: Transduction by Hair Bundle Deflection

Learning Objective: Explain how tip links are involved in mechanotransduction.

Bloom’s Level: 3. Applying

a. the calcium channels are inactivated.

b. the potassium channels are inactivated.

c. the sodium channels are inactivated.

d. all ion channels are broken off along with the tip link.

e. the stereocilia are no longer aligned.

Type: multiple choice question

Title: Chapter 21 Question 23

23. According to the gating spring hypothesis, transduction occurs because

Feedback: Subhead: Transduction by Hair Bundle Deflection

Learning Objective: Explain what the gating spring hypothesis of mechanotransduction in hair cells is.

Bloom’s Level: 2. Understanding

a. Deflection in the negative direction (tallest-to-shortest stereocilia) pulls on the tip links, leading to a deformation and subsequent opening of transduction ion channels.

b. Deflection in the positive direction (shortest-to-tallest stereocilia) pulls on the tip links, leading to a deformation and subsequent opening of transduction ion channels.

c. Tip links are bent, causing a deformation of the aligned stereocilia, thereby opening the transduction ion channels.

d. Tip links are broken off, which facilitates deformation of the aligned stereocilia, thereby opening the transduction ion channels.

e. Calcium-dependent potassium channels are activated, allowing potassium to enter to depolarize the cell.

Type: multiple choice question

Title: Chapter 21 Question 24

24. Based on current knowledge of the tip links, the next experimental step(s) should be to

Feedback: Subhead: Transduction by Hair Bundle Deflection

Learning Objective: Explain what the gating spring hypothesis of mechanotransduction in hair cells is.

Bloom’s Level: 6. Creating

a. characterize the energetics (e.g., energy of activation) of deformation of the stereocilia.

b. determine the minimum amount of force needed to bend the stereocilia to threshold so that action potentials fire.

c. determine the specificity (e.g., potassium? calcium?) of the transduction ion channel.

d. determine the kinetics of ion transport through the transduction channel.

e. purify, characterize, and then clone the proteins of which the tip links are composed.

Type: multiple choice question

Title: Chapter 21 Question 25

25. The olfactory transduction cascade is initiated by

Feedback: Subhead: Olfaction

Learning Objective: Outline the basic steps in the olfactory transduction cascade.

Bloom’s Level: 1. Remembering

a. an odorant molecule binding to a GPCR.

b. the entry of monovalent cations

c. the entry of divalent cations.

d. the exit of both monovalent and divalent anions.

e. the production of cAMP.

Type: multiple choice question

Title: Chapter 21 Question 26

26. Which odorant molecules would probably bind several different isoforms of the same receptor type (GPCR)?

Feedback: Subhead: Olfaction

Learning Objective: Outline the basic steps in the olfactory transduction cascade.

Bloom’s Level: 3. Applying

a. Gasoline

b. Leaves burning

c. Sugar burning

d. Acetone

e. Hot coffee

Type: multiple choice question

Title: Chapter 21 Question 27

27. What kind of experiments or procedures would you have to perform in the olfactory epithelium to show that the vast array of odorant molecules are detected by different GPCRs with different binding affinities?

Feedback: Subhead: Olfaction

Learning Objective: Discuss what accounts for the ability of mammals to discriminate such a large number of odors.

Bloom’s Level: 6. Creating

a. Electron microscopy

b. Fluorescent microscopy

c. Receptor binding

d. Purification, sequencing and cloning of each of the GPCRs

e. Affinity chromatography

Type: multiple choice question

Title: Chapter 21 Question 28

28. What is the plausible range of how different the affinities of the same odorant receptors can be?

Feedback: Subhead: Olfaction

Learning Objective: Discuss what accounts for the ability of mammals to discriminate such a large number of odors.

Bloom’s Level: 4. Analyzing

a. 1–10 mM

b. 1–10 µM

c. 1–10 nM

d. 1–10 pM

e. 1–10 fM

Type: multiple choice question

Title: Chapter 21 Question 29

29. Mammals vary greatly in their ability to smell odors. Which property about the olfactory epithelium do you suppose is responsible for the ability of an animal to detect various odors and its sensitivity to them?

Feedback: Subhead: Olfaction

Learning Objective: Discuss what accounts for the ability of mammals to discriminate such a large number of odors.

Bloom’s Level: 3. Applying

a. The number of turbinates that support the olfactory epithelium

b. The density of odorant receptor genes expressed by different populations of olfactory receptor neurons

c. The actual density of odorant receptors themselves on olfactory sensory neurons

d. The size of the olfactory epithelium

e. The number of turbinates plus the density of the odorant receptors on the olfactory sensory neurons

Type: multiple choice question

Title: Chapter 21 Question 30

30. When people are suffering from head colds, they often cannot smell food as well because

Feedback: Subhead: Mechanisms of Taste (Gustation)

Learning Objective: Explain why discussions of taste and smell are often combined.
Bloom’s Level: 3. Applying

a. the sense of taste is impaired as well.

b. the sense of smell and taste are intertwined centrally.

c. the sense of smell and taste are intertwined peripherally.

d. only the taste rather than their corresponding odors are being detected.

e. the cortical areas for detecting taste and smell are the same.

Type: multiple choice question

Title: Chapter 21 Question 31

31. Olfactory receptor cells are embedded in the ­­­_______, whereas taste receptor cells are embedded in _______.

Feedback: Subhead: Mechanisms of Taste (Gustation)

Learning Objective: Describe how taste receptor cells differ anatomically from olfactory receptor cells.

Bloom’s Level: 4. Analyzing

a. ethmoid bone, mucosa

b. mucus membrane of the olfactory epithelium, taste buds

c. mucus membrane of the olfactory epithelium, the tongue

d. nostrils, taste buds

e. glomeruli, taste buds

Type: multiple choice question

Title: Chapter 21 Question 32

32. Axons of the olfactory receptor cells converge as cranial nerve _______, whereas axons of the taste receptor cells exit the tongue or palate as cranial nerves _______.

Feedback: Subhead: Mechanisms of Taste (Gustation)

Learning Objective: Describe how taste receptor cells differ anatomically from olfactory receptor cells.

Bloom’s Level: 2. Understanding

a. I; VI, VII, IX

b. I; VI, VII, X

c. I; VII, IX

d. I; VII, IX, X

e. VI; I, IX, X

Type: multiple choice question

Title: Chapter 21 Question 33

33. Which of the five categories of taste means that the taste receptor is stimulated by a proton?

Feedback: Subhead: Mechanisms of Taste (Gustation)

Learning Objective: Name the five categories of taste stimuli.

Bloom’s Level: 2. Understanding

a. Sweet

b. Salty

c. Bitter

d. Sour

e. Unami

Type: multiple choice question

Title: Chapter 21 Question 34

34. Which of the five categories of taste means that the taste receptor is stimulated by a sodium ion?

Feedback: Subhead: Mechanisms of Taste (Gustation)

Learning Objective: Name the five categories of taste stimuli.

Bloom’s Level: 2. Understanding

a. Sweet

b. Salty

c. Bitter

d. Sour

e. Unami

Type: multiple choice question

Title: Chapter 21 Question 35

35. How can you group the five different tastes based on the two types of receptors (ion channels vs. GPCRs) they activate?

Feedback: Subhead: Mechanisms of Taste (Gustation)

Learning Objective: State the two basic ways by which taste is transduced.

Bloom’s Level: 1. Remembering

a. Sweet, bitter, salt vs. unami, sour

b. Sweet, bitter, unami vs. sour, salt

c. Sweet, salt, sour vs. unami, bitter

d. Salt, sour, bitter vs. sweet, unami, bitter

e. Salt, sour, unami vs. sweet, bitter

Type: multiple choice question

Title: Chapter 21 Question 36

36. Which type of taste molecules will depolarize the taste receptor cells the fastest?

Feedback: Subhead: Mechanisms of Taste (Gustation)

Learning Objective: State the two basic ways by which taste is transduced.

Bloom’s Level: 3. Applying

a. Salt or sour

b. Salt or unami

c. Salt or sweet

d. Sweet or bitter

e. Sweet or unami

Type: multiple choice question

Title: Chapter 21 Question 37

37. Which of the TRP channels are activated at higher temperatures (greater than 37^⸰C)?

Feedback: Subhead: Temperature and Pain Sensation

Learning Objective: Describe how changes in skin temperature are transduced.

Bloom’s Level: 4. Analysis

a. ANKTM1

b. TRPM8

c. TRPV4

d. TRPV3 and TRPV1

e. TRPV1 and TRPV2

Type: multiple choice question

Title: Chapter 21 Question 38

38. Which of the TRP channels are the most sensitive to even the slightest change in temperature?

Feedback: Subhead: Temperature and Pain Sensation

Learning Objective: Describe how changes in skin temperature are transduced.

Bloom’s Level: 4. Analysis

a. ANKTM1

b. TRPM8

c. TRPV4

d. TRPV3

e. TRPV1

Type: multiple choice question

Title: Chapter 21 Question 39

39. Capsaicin is used as a long-term analgesic because prolonged exposure to it

Feedback: Subhead: Temperature and Pain Sensation

Learning Objective: Describe how sensations of pain are transduced.

Bloom’s Level: 1. Remembering

a. causes death of c-fiber afferents by inward flooding of calcium.

b. causes death of spinal cord dorsal root ganglion cells.

c. causes death of neurons in the somatosensory cortex.

d. blunts the sensitivity of nociceptors.

e. inactivates vanilloid receptors.

Type: multiple choice question

Title: Chapter 21 Question 40

40. It is well known that prolonged direct contact of skin against cold surfaces or ice water (<15^⸰ C) is painful. This is because of

Feedback: Subhead: Temperature and Pain Sensation

Learning Objective: Describe how sensations of pain are transduced.

Bloom’s Level: 3. Appling

a. tissue damage.

b. cell and tissue death.

c. nociceptor activation.

d. ANKTM1 activation.

e. vanilloid receptor activation.

Type: essay/short answer question

Title: Chapter 21 Question 41

41. Discuss the difference(s) between short receptor cells and long receptor cells in terms of temporal and spatial summation.

Feedback: Temporal and spatial summation in short receptor cells is barely an issue: All stimuli act on the cell in one discrete location (e.g., cilia), which are then translated into sub-threshold electrical potentials and action potentials, only having to travel a short distance to the opposite end to release neurotransmitter into the synapse. All potentials, therefore, arrive at nearly the same time and at the same place. In long receptor cells, however, all incoming stimuli (sub-threshold potentials and action potentials) arrive at a dispersed array of dendrites, from which all potentials will be summed both temporally and spatially. If their sum is of threshold strength, the action potentials have to travel down the long axon to reach the terminal boutons, where they will release neurotransmitter into the synapse.

Subhead: Stimulus Coding by Mechanoreceptors

Learning Objective: Describe how short and long receptors differ in morphology and function.

Bloom’s Level: 3. Adapting

Type: essay/short answer question

Title: Chapter 21 Question 42

42. Why is the Weber–Fechner relationship important in animal sensory function?

Feedback: This law takes advantage of the fact that even slight changes sight, hearing and touch can be detected over several orders of magnitude (logarithms), meaning that stimulus coding is not limited to a narrow bandwidth of stimuli (linear relationship). This is of great advantage because the animal can respond and adjust to a wide range of stimulus intensities.

Subhead: Stimulus Coding by Mechanoreceptors

Learning Objective: Explain what the Weber–Fechner relationship is and what its consequences are for the perception of stimuli.

Bloom’s Level: 2. Understanding.

Type: essay/short answer question

Title: Chapter 21 Question 43

43. Describe the morphology of the crayfish stretch receptor.

Feedback: The stretch receptor cell soma lies adjacent to the muscle it innervates. Embedded in the muscle are numerous dendrites. Parallel to the axon, which the cell sends to the central ganglion, are excitatory fibers that innervate the muscle and inhibitory fibers that innervate the dendrites. These excitatory and inhibitory fibers are sent from the ganglion and are compartmentally separate in the muscle they innervate.

Subhead: Stimulus Coding by Mechanoreceptors

Learning Objective: Give two reasons for why the crayfish stretch receptor is such a useful model for mechanosensory investigations.

Bloom’s Level: 2. Understanding

Type: essay/short answer question

Title: Chapter 21 Question 44

44. What is the difference between wearing a comfortable pair of shoes and a pair of shoes that is so uncomfortable that it is painful?

Feedback: A comfortable pair of shoes represents rapidly adapting receptors, which, at first, fire a fierce volley of action potentials when putting the shoes on, but which then rapidly dissipate over the next few seconds. The painful pair of shoes represents slowly adapting fibers and also cause the firing of an intense barrage of action potentials, but which do not dissipate over time; that is, the pain is felt via the nociceptors in your feet indefinitely or until the shoes are removed.

Subhead: Stimulus Coding by Mechanoreceptors

Learning Objective: Differentiate between rapidly adapting receptors and slowly adapting receptors.

Bloom’s Level: 3. Adapting

Type: essay/short answer question

Title: Chapter 21 Question 45

45. How does a muscle spindle respond to statically vs. dynamically?

Feedback: Static response: Upon slowly stretching a muscle spindle, both primary and secondary endings respond by firing action potentials, the frequency of which, are proportional to the extent of stretch. These primary and secondary endings of the nuclear chain fibers are innervated by Group Ia and II afferents, respectively. Dynamic response: If the spindle length suddenly increases, there will be vigorous response from the primary sensory fiber, innervated by Group Ia afferents wrapped around the nuclear bag fiber.

Subhead: Stimulus Coding by Mechanoreceptors

Learning Objective: Discuss the functional differences between Group Ia and Group II afferent fibers.

Bloom’s Level: 2. Understanding

Type: essay/short answer question

Title: Chapter 21 Question 46

46. Which anatomical parts about the cochlea and semicircular canals would be analogous in terms of the stimulus that activates them?

Feedback: The base (oval window) of the cochlea and the semicircular canals both respond to low-frequency vibrations: the oval window segment of the cochlea responds to low-frequency sounds and the semicircular canals respond to the slowly-moving head as it swivels or moves in space.

Subhead: Transduction by Mechanosensory Cells

Learning Objective: Name the two structures in the inner ear where mechanosensitive hair cells are found.

Bloom’s Level: 2. Understanding

Type: essay/short answer question

Title: Chapter 21 Question 47

47. What comes in direct contact with the stereocilia of the hair cells in the cochlea and semicircular canals?

Feedback: The hair cells in the cochlea are stimulated by displacement between the basilar and tectorial membranes, whereas the hair cells in the saccule and utricle are stimulated by the overlying otolithic membrane. In the ampula, movement of the head causes inertial displacement of endolymph, which then causes bending in one direction or the other, resulting in either depolarization or hyperpolarization.

Subhead: Transduction by Mechanosensory Cells

Learning Objective: Describe the basic structure and functional specializations of hair cell receptors.

Bloom’s level: 2. Understanding

Type: essay/short answer question

Title: Chapter 21 Question 48

48. Explain one reason why hearing loss in humans is permanent.

Feedback: There is evidence that damaged tip links that allow the stereocilia to fall out of alignment is a marker for permanent damage and hearing loss. In this way, mechanoelectrical transduction (MET) is impaired, calcium channels are no longer functional, and the auditory nerve no longer transmits impulses (or at least, is compromised).

Subhead: Transduction by Hair Bundle Deflection

Learning Objective: Explain how tip links are involved in mechanotransduction.

Bloom’s Level: 3. Applying

Type: essay/short answer question

Title: Chapter 21 Question 49

49. At least two distinct cadherins have been identified as being essential for the function of tip links. What kind(s) of experiments/studies should be performed to characterize how tip links open the transduction channels?

Feedback: The cadherins and transduction channels should be purified, cloned and sequenced. Then, molecular cloning techniques, such as site-directed mutagenesis should be performed to determine which residues are involved in the opening and closing the spring and transduction channel. Computer modeling and docking studies should also be performed to determine the energetics and forces necessary to operate the gating spring.

Subhead: Transduction by Hair Bundle Deflection

Learning Objective: Explain what the gating spring hypothesis of mechanotransduction in hair cells is.

Bloom’s Level: 6. Creating

Type: essay/short answer question

Title: Chapter 21 Question 50

50. Given how sensitive odor detection is, what could happen at the molecular cascade level that would give rise to anosmia or an increased tolerance to certain odors?

Feedback: Anosmia indicates that some kind of neurological or physical trauma or damage or aging has been taking place. In any case, decreased sensitivity could mean that fewer ion channels are present in the sensory cilia. Prolonged exposure to an odor and subsequent increased tolerance to it could mean that there are fewer ion channels present per cubic area of cell volume. Density of such ion channels could be changed by invoking cAMP‘s other function of a second messenger, besides that of simply an ion channel regulator. That is, as a second messenger, cAMP can then activate kinases, such as protein kinase A, which could then phosphorylate transcription factors, causing changes in gene expression of ion channel subunits.

Subhead: Olfaction

Learning Objective: Outline the basic steps in the olfactory transduction cascade.

Bloom’s Level: 3. Applying

Type: essay/short answer question

Title: Chapter 21 Question 51

51. Given the relative simplicity of GPCRs, but the potentially enormous number of different odor ligands that can bind them, what might be possible ways that can give rise to such a diverse family of GPCR variants?

Feedback: Although the family of GPCRs is arguably one of the largest protein families in the human genome, comprising approximately 1% of it, all GPCRs follow a common structural motif: seven transmembrane spanning segments with both extracellular and intracellular loops, extracellular N-terminus, cytoplasmic C-terminus. Variations in the lengths and conformation of any of these segments can result in a functionally different receptor, with different binding affinities for a wide and diverse array of different odor ligands. Moreover, most GPCRs actually exist in the membrane as dimers, and not necessarily as homodimers, but rather, as heterodimers.

Subhead: Olfaction

Learning Objective: Discuss what accounts for the ability of mammals to discriminate such a large number of odors.

Bloom’s Level: 4. Analyzing

Type: essay/short answer question

Title: Chapter 21 Question 52

52. You are a forensic investigator at a crime scene when you enter a small poorly ventilated room, in which you find a badly decomposing body. The stench is overwhelming as you complete your part of the investigation. After you leave the room, you can still smell the rotting body and continue to do so, even over the next several days and although the stench does wane a little, you could swear that you can taste it. What do you suppose is the reason for continuing to smell and even taste the odor, despite having left the scene?

Feedback: Odor molecules of the decomposing body have likely stuck to the hairs in your nostrils and which continue to waft odor molecules into your olfactory epithelium.

Subhead: Mechanisms of Taste (Gustation)

Learning Objective: Explain why discussions of taste and smell are often combined.

Bloom’s Level: 3. Applying

Type: essay/short answer question

Title: Chapter 21 Question 53

53. How do the afferents of taste receptor cells and olfactory receptor cells differ?

Feedback: A taste bud is comprised of basal cells, supporting cells and taste cell receptors; the taste cell receptors make synaptic contact with afferent nerve fibers, which converge as the facial, glossopharyngeal and vagus cranial nerves. In the olfactory epithelium, there are also basal cells, supporting cells and receptor cells. However, here, the receptor cells send their own axons through the cribriform plate in the ethmoid bone to become the olfactory cranial nerve.

Subhead: Mechanisms of Taste (Gustation)

Learning Objective: Describe how taste receptor cells differ anatomically from olfactory receptor cells.

Bloom’s Level: 2. Understanding

Type: essay/short answer question

Title: Chapter 21 Question 54

54. Is it valid to apply the Weber–Fechner Law to changes in skin temperature.

Feedback: No. The Weber–Fechner Law uses a logarithmic scale of stimulus intensity and applies to sound, light, and touch. The scale of changes in skin temperature covers a range that is too narrow and would result in tissue damage if the W-F Law were applied.

Subhead: Temperature and Pain Sensation

Learning Objective: Describe how changes in skin temperature are transduced.

Bloom’s Level: 3. Applying

Type: essay/short answer question

Title: Chapter 21 Question 55

55. Could the expression “the pain is all in your head” be considered valid?

Feedback: Yes. Pain is a percept. Although pain can originate in the periphery, detected by nociceptors or thermoreceptors, the perception of pain actually occurs in the brain. From the periphery, pain signals are carried to the somatosensory cortex (among several other places) largely by the anterolateral system; from the head (e.g., mouth, teeth), by the trigeminal nerve (CN V). It is in the somatosensory cortex, therefore, where pain is perceived.

Subhead: Temperature and Pain Sensation

Learning Objective: Describe how sensations of pain are transduced.

Bloom’s Level: 3. Applying