Deck 21: Sensory Transduction

Question 1

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

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.

Answer 1

C

Question 2

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

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.

Answer 2

A

Question 3

Which would serve to demonstrate the workings of the Weber-Fechner Relationship?

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.

Answer 3

D

Question 4

Which is true about the Weber-Fechner Law?

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.

Question 5

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

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.

Question 6

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

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.

Question 7

Which is true about adaptation?

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.

Question 8

Which is probably not an example of adaptation?

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

Question 9

Which is an example of rapidly adapting receptors responding?

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

Question 10

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

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.

Question 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?

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

Question 12

How are nuclear bag fibers and nuclear chain fibers similar?

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

Question 13

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

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.

Question 14

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

A) Group Ia afferents
B) Group II afferents
C) Both group Ia and II afferents
D) Gamma motoneurons
E) Alpha motoneurons

Question 15

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

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.

Question 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?

A) 1
B) 2
C) 3
D) 4
E) 5

Question 17

The hair on hair cell receptors are composed of

A) actin polymers.
B) tubulin polymers.
C) keratin.
D) a mixture of actin and lipids.
E) a mixture of actin and keratin.

Question 18

Depolarization of hair cell receptors is caused by

A) sodium entry.
B) potassium entry.
C) calcium entry.
D) chloride exit.
E) potassium entry and chloride exit.

Question 19

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

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

Question 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?

A) 10 nm
B) 50 nm
C) 100 nm
D) 200 nm
E) 500 nm

Question 21

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

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.

Question 22

Breaking off the tip link abolishes mechanotransduction because

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.

Question 23

According to the gating spring hypothesis, transduction occurs because

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.

Question 24

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

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.

Question 25

The olfactory transduction cascade is initiated by

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.

Question 26

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

A) Gasoline
B) Leaves burning
C) Sugar burning
D) Acetone
E) Hot coffee

Question 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?

A) Electron microscopy
B) Fluorescent microscopy
C) Receptor binding
D) Purification, sequencing and cloning of each of the GPCRs
E) Affinity chromatography

Question 28

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

A) 1-10 mM
B) 1-10 µM
C) 1-10 nM
D) 1-10 pM
E) 1-10 fM

Question 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?

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

Question 30

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

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.

Question 31

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

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

Question 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 _______.

A) I; VI, VII, IX
B) I; VI, VII, X
C) I; VII, IX
D) I; VII, IX, X
E) VI; I, IX, X

Question 33

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

A) Sweet
B) Salty
C) Bitter
D) Sour
E) Unami

Question 34

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

A) Sweet
B) Salty
C) Bitter
D) Sour
E) Unami

Question 35

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

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

Question 36

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

A) Salt or sour
B) Salt or unami
C) Salt or sweet
D) Sweet or bitter
E) Sweet or unami

Question 37

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

A) ANKTM1
B) TRPM8
C) TRPV4
D) TRPV3 and TRPV1
E) TRPV1 and TRPV2

Question 38

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

A) ANKTM1
B) TRPM8
C) TRPV4
D) TRPV3
E) TRPV1

Question 39

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

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.

Question 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

A) tissue damage.
B) cell and tissue death.
C) nociceptor activation.
D) ANKTM1 activation.
E) vanilloid receptor activation.

Question 41

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

Question 42

Why is the Weber-Fechner relationship important in animal sensory function?

Question 43

Describe the morphology of the crayfish stretch receptor.

Question 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?

Question 45

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

Question 46

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

Question 47

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

Question 48

Explain one reason why hearing loss in humans is permanent.

Question 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?

Question 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?

Question 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?

Question 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?

Question 53

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

Question 54

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

Question 55

Could the expression "the pain is all in your head" be considered valid?