Chapter 44, Problem 1TYK

In the human ear, how do different hair cells respond to different frequencies of sound?

a. Waves of pressure move through the fluid in the cochlea.

b. Hair cells are “sandwiched” between membranes.

c. Receptor proteins in the stereocilia of each hair cell are different; each protein responds to a certain range of frequencies.

d. Because the basilar membrane varies in stiffness, it vibrates in certain places in response to certain frequencies.

Summary Introduction

Introduction:

The human ear apart from performing the function of hearing is also responsible for the maintenance of balance in the body. The hair cells present in the ear run through the basilar membrane.

Answer to Problem 1TYK

Correct answer:

The difference in the stiffness of the basilar membrane and its vibration at some places is caused in response to certain frequencies. Hearing refers to the sensation generated by the wavelike alterations in the air pressure known as sound.

Explanation of Solution

Explanation/Justification for the correct answer:

Option (d) is given as the stiffness variation of the basilar membrane and the vibration of hair cells in response to certain frequencies. The hair cells forming the rows within the middle chamber are pierced in a tissue, which is deposited on the basilar membrane. Some portions of the basilar membrane vibrate in response to specific frequencies and this causes the bending of the hair cell stereocilia. The hair cells present in the particular region on the membrane respond to the sound of a particular frequency. Hence, Option (d) is correct.

Explanation for incorrect answers:

Option (a) is given as the movement of the waves of pressure in the cochlea through the fluid. Hearing refers to the sensation generated by the wavelike alterations in the air pressure known as sound. The sound is composed of waves of pressure in the water or air. However, it does not describe the response of the hair cells. So, it is a wrong answer.

Option (b) is given that the hair cells are sandwiched between the membranes. The hair cells are embedded in the tissue that sits atop the basilar membrane. In addition to this, the hair cells touch another small surface known as a tectorial membrane. This results in the formation of the sandwich. However, it does not describe the response of the hair cells. So, it is a wrong answer.

Option (c) is given as the generation of the response by the proteins present in the stereocilia to a certain range of frequencies only. However, it is not the mechanism of response generation by the hair cells in order to aid hearing. So, it is a wrong answer.

Hence, options (a), (b), and (c) are incorrect.

Conclusion

Thus, the hair cells, which are present in the basilar membrane, generate response to different frequencies as a result of variation in the stiffness of the basilar membrane. Furthermore, the vibration occurs only in response to certain frequencies.