Chapter 8: Somatosensory Neurotransmission: Touch, Pain, & Temperature

Chapter 8. Somatosensory Neurotransmission: Touch, Pain, & Temperature

A 28-year-old man was seen by a neurologist because he had experienced prolonged episodes of tingling and numbness in his right arm. He underwent a neurologic exam to evaluate his sensory nervous system. Which of the following cutaneous mechanoreceptors is correctly paired with the type of stimulus to which it is most apt to respond?

A. Pacinian corpuscle and rapid vibration

B. Meissner corpuscle and skin stretch

C. Merkel cells and slow vibration

D. Ruffini corpuscles and sustained pressure

An MD/PhD student was recording responses in different cutaneous receptors and noted the following. One receptor was inactive until the skin temperature was increased to 33°C and then its firing rate continued to increase as the skin temperature was gradually raised to 45°C. A second receptor was inactive until the skin temperature reached 46°C. A third receptor was inactive at skin temperatures of 40°C, but then steadily increases its firing rate as skin temperature was lowered to 24°C. For each of these cases, classify the type of receptor and the nonselective cation channel that was possibly activated.

A. Receptor one is a thermal nociceptor and the channel activated was TRPV1; receptor two is a thermal nociceptor and the channel activated was TRPA1; receptor three was an innocuous cold receptor and the channel activated was TRPV4.

B. Receptor one is an innocuous warm receptor and the channel activated was TRPV1; receptor two is a thermal nociceptor and the channel activated was TRPM8; receptor three was an innocuous cold receptor and the channel activated was TRPV3.

C. Receptor one is an innocuous warm receptor and the channel activated was TRPV3; receptor two is a thermal nociceptor and the channel activated was TRPV1; receptor three was an innocuous cold receptor and the channel activated was TRPM8.

D. Receptor one is a thermal nociceptor and the channel activated was TRPA1; receptor two is a thermal nociceptor and the channel activated was TRPV1; receptor three was an innocuous cold receptor and the channel activated was TRPM8.

List the steps involved in the generation of an action potential in a sensory nerve fiber beginning with the stimulation of a Pacinian corpuscle.

A. Light touch is applied to the Pacinian corpuscle, and a receptor potential is generated; as the pressure is increased, the size of the receptor potential is increased; when it reaches 30 mV, an action potential is produced at a point of the sensory ...