It is late at night, and you are at the library doing some last-minute studying for your comparative physiology exam. You suddenly feel hungry, and you head to the vending machine to buy a snack

Question

Explain the role of the following sensory structures/organs, and give an example of how/when they will be active during this task.

a. Merkel cell
b. Gustatory receptors (choose one)
c. Macula of a utricle
d. Cone photoreceptor

What will be an ideal response?

Answer 1

Answer: Answers to this can be somewhat creative in giving examples for the use of these receptors.
a. Merkel cells are used for fine tactile discrimination and may be used for handling coins, opening a bag of food, touching the food, etc. (see page 274).
b. Gustatory receptors: Depending on the type of snack, the student may describe the function of any of the receptors from page 271 (salty, sour, bitter, umami, sweet). For example, a bag of chips may be purchased, and the taste bud would be active with a particular focus on the reception of a "salty" signal. Sodium from salty food enters the receptor cell through a sodium channel, which causes cell depolarization. This depolarization results in calcium influx and consequent neurotransmitter release. The afferent neuron is activated.
c. The utricle is a part of the vestibular apparatus that is sensitive to linear acceleration. It would be active during forward walking motion. (see page 281 Fig. 7.24a)
d. Cone photoreceptors in vertebrates detect color. Therefore, these would be active when looking at all the different packages in the vending machine. (see page 289-290, Figure 7.31, and Table 7.21)