Question

multiple choice question
the thoracic pump generates force by which of the following?

increased abdominal pressure created during exhalation
increased abdominal pressure created during inhalation
increased abdominal pressure created by contraction of the rectus abdominus

Explanation:

The thoracic pump's force generation related to abdominal pressure: During inhalation, the diaphragm descends, increasing abdominal pressure (as the abdominal contents are displaced). Exhalation typically reduces abdominal pressure, and rectus abdominis contraction is more for other functions (like trunk flexion) rather than thoracic pump force. So the correct mechanism is increased abdominal pressure during inhalation.

Answer:

B. Increased abdominal pressure created during inhalation (assuming the options are labeled A, B, C with the second option as B; if original labels differ, adjust to match the option text: "Increased abdominal pressure created during inhalation")