Deck 7: Sensors II: Sensing on Contact

Question 1

What are two ways of classifying sensory systems as described in opening paragraphs of chapters 6 and 7? Propose another method that you might use to classify sensory systems and state how the senses presented in chapters 6 and 7 would be incorporated.

Answer 1

No Answer.

Question 2

Which of the following is true regarding mechanosensory neurons?

A) Their axons terminate as free nerve-endings in the skin.
B) Their axons terminate or are found in close association with specialized mechanosensory structures.
C) Ion channels that are "gated" by mechanical stimuli depolarize mechanosensory neurons.
D) All of the above are true.

Answer 2

D

Question 3

Analyze figure 7.1,In the text Which of the following is NOT true regarding the anatomy of mechanosensation?

A) Mechanosensory neurons are located in the dorsal root ganglion outside of the spinal cord.
B) Mechanosensory neurons synapse with spinal cord neurons in the ventral horn of the spinal cord.
C) Mechanosensory neurons receive input regarding movement of hairs as well as mechanical stimuli in the dermal tissue.
D) Merkel cells are generally found in the deepest layers of the dermis.

Answer 3

B

Question 4

Analyze figure 7.2, In the text Which of the following can you conclude by the data presented in this figure?

A) Merkel cells readily adapt to mechanical stimulation, with their response quickly diminishing even as a stimulus is applied.
B) Merkel cells respond to an increase in mechanical pressure by increasing the amount of neurotransmitter released.
C) Axons of mechanosensory neurons illustrate the neural organization principle of divergence in their innervation of Merkel cells.
D) All of the above can be concluded from these data.

Question 5

Which of the following is true of Merkel cells?

A) Merkel cells are located in the deepest layers of the dermis.
B) Merkel cells must be present in order for mechanosensory axons to detect mechanosensory stimuli.
C) Merkel cells communicate with mechanosensory axons via glutamatergic synapses.
D) Merkel cells respond to deep pressure on the skin and are primarily found in less sensitive skin areas such as the calf.
E) all of the above are true statements.

Question 6

Which of the following is true of Meissner's corpuscles?

A) Meissner's corpuscles are located in the deepest layers of the dermis.
B) Lamellar cells must be present in order for mechanosensory axons to detect mechanical stimuli.
C) Lamellar cells are similar to Merkel cells in that they communicate with mechanosensory axons via glutamatergic synapses.
D) Merkel cells respond to low frequency vibration and rapidly adapt to stimuli.
E) all of the above are true statements.

Question 7

Which of the following is NOT true of Pacinian Corpuscles?

A) Pacinian corpuscles are located in the deepest layers of the dermis.
B) Pacinian corpuscles consist of many glial-like cells surrounding a mechanosensory axon.
C) Mechanosensory neurons that innervate Pacinian corpuscles rapidly adapt to stimuli.
D) Mechanosensory neurons that innervate Pacinian corpuscles respond to low frequency vibration.
E) Mechanosensory ion channels are likely located in the mechanosensory axon of each Pacinian corpuscle, and are not found in the glia.

Question 8

You are a scientist studying mechanosensation, and are performing electrical recordings on a single mechanosensory axon that innervates a finger. You find that when slight pressure is applied to the finger, the axon responds with multiple action potentials that do not decrease in frequency over time. You have likely found an axon associated with which cell type/structure?

A) Merkel cells
B) Pacinian corpuscles
C) Meissner's corpuscles
D) None of the above

Question 9

A patient is badly burned, and much of the epidermis is destroyed, along with the most superficial layers of the dermis. Which mechanosensory function is most likely to be retained in this patient?

A) The ability to detect slight mechanical indentation of the skin
B) The ability to detect low frequency vibration
C) The ability to detect high frequency vibration
D) None of the above

Question 10

Which of the following is NOT true regarding neurons in the dorsal root ganglia?

A) Their axons can be 6-10 feet long in some animals.
B) They have two axons that project from either side of the cell body and are bipolar.
C) They primarily convey sensory stimuli to the spinal cord.
D) They have a single axon that splits in a T-shaped junction outside the cell body and are pseudounipolar.

Question 11

Analyze Figure 7.6, In the text What can be concluded from these data?

A) C fibers respond to dull pain and noxious heat.
B) There are two groups of myelinated sensory nerve fibers that differ in size.
C) There are two groups of sensory nerve fibers that differ in myelination.
D) All of the above can be concluded from these data.

Question 12

You are a scientist studying the impact of a drug on conduction velocity. You find that you are unable to identify any axons that conduct action potentials faster than 70 m/s. You conclude that the drug likely has a negative effect on which type of neurons?

A) A-alpha fibers
B) A-beta fibers
C) A-gamma fibers
D) A-delta fibers
E) C-fibers

Question 13

You are a scientist studying the impact of a disease that destroys myelin in peripheral nerves. What might be a symptom of such a disease?

A) Impaired muscle function
B) Impaired mechanosensory function
C) Impaired temperature-sensation (thermosensation)
D) all of the above might be affected

Question 14

You apply a colored axonal tracer to dorsal root ganglion neurons that are associated with Merkel cells. You would expect that you might find color in which areas within the spinal cord?

A) Rexed lamina II
B) Rexed lamina VIII
C) Rexed lamina IX
D) you would expect to find color in each of the above areas

Question 15

Somatosensory neurons in the fingertips in general have (larger/smaller) receptive fields than somatosensory neurons that innervate the calf.

Question 16

The portion of the body's surface that is served by each touch sensor is defined as that sensor's ________________________.

Question 17

You have learned about somatotopic, tonotopic, and chemotopic mapping in the brain. Compose a short description of these ideas, and tell how these organizational schemes are similar and different from each other.

Question 18

Sensory neurons that respond to inflammation, extremes of temperatures, or other painful (noxious) stimuli are referred to as _____________________.

Question 19

Nociceptors are polymodal sensory neurons. What mechanisms might account for how these sensory neurons are involved in the detection of more than one sensory modality? What might be an evolutionary benefit of this, rather than having unimodal detectors convey painful sensations to the CNS?

Question 20

Predict how an individual's ability to detect painful stimuli might change if they have a disease that impairs the function of myelinated peripheral sensory neurons.

Question 21

Create a sketch that shows the anatomical differences between mechanosensory fibers and nociceptive fibers as they enter the spinal cord and synapse with neurons that project rostrally.

Question 22

A patient is in a severe car accident and suffers damage to the spinal cord. They no longer experience pain in their left leg, but their ability to feel touch and vibration in the left leg remains normal. Which side of the spinal cord was affected by injury?

A) left
B) right
C) both

Question 23

A patient presents to the clinic with a severe, belt-like rash that is confined to a single area and has clearly-defined borders. Given the information presented in this chapter, the most likely explanation is __________________.
a) shingles
b) Brown-Sequard syndrome
c) a demyelinating disease that primary affects A-delta fibers
d) none of the above

Question 24

Medications that reduce pain are known as __________________.

Question 25

Opioids such as morphine reduce pain by which of the following mechanisms?

A) blocking receptors that detect pain-producing compounds
B) activating receptors that lead to neuronal hyperpolarization
C) blocking receptors that lead to neuronal depolarization
D) blocking sodium channels that are expressed in a subset of nociceptors

Question 26

Compare and contrast molecular receptors expressed on sensory neurons. Opioid receptors are most similar to which other type of molecular receptor?

A) sodium channels in nociceptive neurons
B) TRP channels in thermosensitive neurons
C) odorant receptors in olfactory neurons
D) potassium channels in mechanosensory neurons

Question 27

If you were to perform an analysis of pain sensing neurons exposed to the centipede toxin described in section 7.2, what would you be likely to find?

A) action potentials are reduced or absent in these cells
B) action potentials are increased in these cells
C) the cells would no longer be able to release neurotransmitter after depolarization of the axon terminal
D) the cells would release an excessive amount of neurotransmitter from the axon terminal

Question 28

TENS (transcutaneous electrical nerve stimulation) exerts its effect because ____________________.

A) the activity of mechanosensory neurons has an inhibitory effect on the activity of nociceptors that innervate the same region.
B) it serves to close the "gate" described in the gate theory of pain
C) it selectively can act on large diameter neurons rather than small diameter neurons
D) all of the above

Question 29

Which of the following is NOT true of neurogenic inflammation?

A) it is blocked by lidocaine
B) it leads to release of Substance P and CGRP, which increase blood flow to the affected region
C) it promotes the release of histamine in the affected area, leading to swelling
D) it describes inflammation that occurs to injured neurons

Question 30

We often think of pain as a bad thing - and it certainly is in terms of its emotional quality. Why then do you think humans and other animals have evolved the ability to perceive pain? In what sense is pain a good thing?

Question 31

Neurons are one particular cell type, but-as you can see in this chapter and others-neurons display remarkable diversity in their structure and function. Give 3 examples from this chapter of how gene expression differences lead to different types of neurons.

Question 32

You feel a cool breeze on your skin. Though a variety of mechanisms are involved in this sensation, it is probably most due to the function of ___________________ in peripheral sensory neurons.

A) TRPV1
B) TRPM8
C) TRPA1
D) TRPM4

Question 33

Analyze Figure 7.11, In the text From these data you might conclude which of the following?

A) Mice without functional TRPM8 cannot tell the difference between 20C and 30C.
B) Wildtype mice prefer a temperature of about 20C.
C) TRPM8 permits a cation influx into cells after it is activated by cold temperatures.
D) Mice without functional TRPM8 lose their ability to perceive cold temperatures

Question 34

Analyze Figure 7.12, In the text What would be reasonable conclusions you could draw from these data?

A) Habanero peppers contain a compound that can activate TRPV1.
B) Wax peppers contain no capsaicin.
C) Thai green peppers contain more capsaicin than wax peppers.
D) Capsaicin is the ingredient that makes chili peppers taste "hot".

Question 35

Which of the following is NOT true regarding gustation?

A) There are several hundred different fundamental taste sensation recognized by taste receptors.
B) Taste buds contain 50-150 taste cells.
C) Molecular taste receptors are found in the tongue and in tissues such as the stomach and respiratory tract.
D) The tastes of sweet, bitter, and umami are mediated by G-protein coupled receptors.

Question 36

Which of the following is NOT an accurate comparison between gustation and phototransduction?

A) T1 receptors and rhodopsin are molecules that contain 7 membrane-spanning domains
B) The G-alpha subunits from T1 receptors and rhodopsin activates a phosphodiesterase
C) Sensory cells that respond to sweet and photons depolarize when presented with sweet tastants or photons
D) The detection of photons and sweet tastants both lead to changes in intracellular calcium levels in sensory cells.

Question 37

Analzye Figure 7.14. In the text What can you conclude from these data?

A) T1R3 is necessary for the detection of umami
B) T1R2 is necessary for the detection of sweet
C) T1R3 is necessary for the detection of both umami and sweet
D) all of the above can be concluded from these data

Question 38

Match the tastant with its role in gustation.
-________ helps to detect foods that are spoiled or unripe

A) acid
B) bitter
C)umami
D)sweet.

Question 39

Match the tastant with its role in gustation.
-________ helps to detect potentially harmful compounds

A) acid
B) bitter
C)umami
D)sweet.

Question 40

Match the tastant with its role in gustation.
-________ helps to detect that a food contains protein

A) acid
B) bitter
C)umami
D)sweet.

Question 41

Match the tastant with its role in gustation.
-________ helps to detect when a food contains carbohydrates

A) acid
B) bitter
C)umami
D)sweet.

Question 42

Analzye Figure 7.16. In the text What can you conclude from these data?

A) There is a gustatopic map in the medulla where similar tastes are recognized by clusters of adjacent neurons
B) Salt-tuned neurons seem to be rapidly adapting and decrease their response even as a stimulus is sustained
C) Sour-tuned neurons respond to NaCl, but not HCl
D) none of the above can be concluded from these data

Question 43

Construct an argument that the ability to discriminate different tastes is evolutionarily advantageous. In your answer, choose 3 examples from the reading of how differences in tasting between species illustrates an adaptation to an evolutionary niche.

Question 44

Analzye Figure 7.16. In the text What can you conclude from these data?

A) Animals that are injected with THC are more likely to crave sweet foods than animals injected with 2-AG
B) Wild-type mice injected with 2-AG experience increased responses to both sucrose and HCl
C) Wild-type mice injected with 2-AG experience increased responses to saccharine but not quinine
D) CB1 knockout mice experience injected with 2-AG experience an increased response to HCl

Question 45

What is an endogenous cannabinoid? Is an endogenous cannabinoid different than cannibinoids found in marijuana plants? Describe one role of an endongenous cannabinoid in gustation.

Question 46

Variations in human genes, such as T1R2, make people differentially sensitive to certain tastes. Propose a reason that so much variation in these genes can exist in the human population. Predict whether you think that our species will eventually have one form of this receptor, a non-functional receptor like cats, or will continue to have many variants and give rationale for your prediction.

Question 47

It is sometimes said that humans have 5 senses. Based on your reading of chapters 6 and 7, do you believe this is the case? Propose a definition of what constitutes a "sense" and give a rough estimate of how many senses humans possess. Note that there is not a correct answer for this number-just be sure to justify your response.

Question 48

Which of the following is NOT true regarding acid-sensing in the body?

A) carbon dioxide build-up in the body leads to decreased pH
B) acids in tissues lead to sensations of pain
C) signals sensed by acid-sensing mechanisms can modulate breathing rates in organisms
D) only acid-sensing ion channels (ASICs) sense decreases in pH

Question 49

Analyze Figure b7.4.In the text What can you conclude from these data?

A) Bats are more likely to hibernate than squirrels or primates
B) Nav1.7 channels have more variation among animals that hibernate
C) Species that hibernate are more likely to contain Nav1.7 channels than species that do not hibernate
D) Hibernating organisms often contain Nav1.7 channels that are less sensitive than those in non-hibernating organisms

Question 50

What is NOT true of the carotid body?

A) It is a collection of cells found where the carotid artery divides to form the external and internal carotid branches.
B) it detects blood oxygenation levels
C) glomus cells primarily use dopamine as their neurotransmitter
D) glomus cells depolarize when oxygen levels drop

Question 51

The name of the sense responsible for determining the position and movements of your body parts relative to each other is known as _________________________.

Question 52

Compare and contrast the mechanosensory organs in muscles responsible for proprioception. Which of the following is NOT an accurate statement?

A) Most proprioceptive sensors are located in the joints.
B) Golgi tendon organs sense stretch in the tendon via mechanosensory ion channels
C) Muscle spindles sense both the magnitude and velocity of muscle stretch
D) Both golgi tendon organs and muscle spindles are innervated by myelinated nerve fibers

Question 53

Which of the following is NOT true of the vestibular system?

A) Head tilt and acceleration is detected by hair cells that sense fluid movement
B) The cochlea is the sensory organ associated with sensing head tilt and acceleration
C) The tips of hair cells that sense acceleration respond to movement of the otoconial membrane
D) saccular hair cells respond to movements such as that experienced when riding an elevator

Question 54

Compare and contrast the sensory cells that permit the detection of sound vs. the sensory cells the detect head movement and acceleration. In your answer, discuss where the cells are located and the structures associated with each that facilitate their functions.

Question 55

In certain amusement park rides, individuals are seated in front of a screen and their seats rock, move up and down, and tilt to simulate the types of stimuli they would be experiencing while on a boat, spaceship, or other vehicle. Using your knowledge of the vestibular system, construct an argument that if such a simulation were perfectly designed, a viewer could be completely fooled into believing they were actually moving through space. Be sure to justify your answer with specific reference to the structural features of the utricle, saccule, and semicircular canals.

Question 56

Match the structures to the function of the parts of the vestibular system using the following words/phrases:
-_______________________ utricles

A) vertical acceleration
B) forward head tilt
C) head rotation.

Question 57

Match the structures to the function of the parts of the vestibular system using the following words/phrases:
-_______________________ saccules

A) vertical acceleration
B) forward head tilt
C) head rotation.

Question 58

Match the structures to the function of the parts of the vestibular system using the following words/phrases:
-_______________________ semicircular canals

A) vertical acceleration
B) forward head tilt
C) head rotation.

Question 59

Occasionally otoconia in the vestibular organs fall out of the dense gelatinous matrix that holds them and make contact directly with hair cells. Predict what symptoms you might expect? Look up the disorder Benign Paroxysmal Positional Vertigo and state whether your prediction was accurate.

Question 60

Analyze Figure 7.19.In the text Which of the following can be concluded from these data?

A) Some A-alpha fibers are motor neurons
B) C-fibers are unmyelinated
C) Sensory fibers can be divided into 3 classes based on their size
D) A-delta fibers respond to pressure and pain

Question 61

Analyze Figure 7.18.In the text What can you conclude from these data?

A) The darkly-stained axons are myelinated.
B) The darkly-stained axons are unmyelinated.
C) The darkly-stained axons respond to passive stretch.
D) The darkly-stained axons are A-alpha fibers.
E) none of the above

Question 62

ATP is a molecule that is used widely in cells as a readily-available energy source. However this chapter describes several other functions of ATP. Outline several roles for ATP other than energy storage that are described in this chapter.

Question 63

What is the primary function of the vestibular system?

A) To detect movement of joints.
B) To detect stretch of muscles.
C) To detect movements such as acceleration and head tilt.
D) To detect tactile stimuli such as warm and cold temperatures.

Question 64

Which of the following is true of enkephalins?

A) They are an example of a cannabinoid.
B) They lessen the perception of pain during acute stress.
C) They are primarily used as a neurotransmitter in glomus cells that detect blood oxygen.
D) all of the above