Problem 6 - Biology: The Dynamic Science

Question

A speed skater is finishing his last lap. At this time: a. the diaphragm and rib muscles contract when he exhales. b. positive pressure brings air into his lungs. c. his lungs undergo an elastic recoil when he inhales. d. his tidal volume is at vital capacity. e. his residual volume momentarily reaches zero.

Step-by-Step Solution

Answer

For the speed skater in the scenario, a. is correct, while b., c., d., and e. are incorrect.

Step 1: Understand the terms

Before providing the correct answer, it's crucial to understand what each term in the exercise means: Diaphragm, rib muscles, contract, exhale, positive pressure, elastic recoil, inhale, tidal volume, vital capacity, and residual volume.

Step 2: Process Explanation

a. When the speed skater exhales, the diaphragm and rib muscles contract. This is because exhaling requires a decrease in lung volume, which is accomplished by the contraction of these muscles. \n b. Positive pressure does not bring air into the lungs. On the contrary, negative pressure (created by the expansion of the chest cavity) brings air into the lungs. \n c. Elastic recoil of the lungs does not occur during inhalation. It happens when the person exhales, allowing the lungs to return to their resting volume. \n d. Tidal volume refers to the volume of air displaced between normal inhalation and exhalation when the person is at rest. During strenuous exercise, such as speed skating, this would increase, but it would not reach vital capacity (the maximal amount of air a person can expel from the lungs after a maximum inhalation).\n e. Residual volume, the volume of air still remaining in the lungs after the most forcible expiration possible, never reaches zero. Even when we exhale completely, there’s always some air left in our lungs that helps to keep them open.

Step 3: Concluding the answers

Therefore, in the given scenario: a. is correct, b. is incorrect, c. is incorrect, d. is incorrect, and e. is incorrect.