Under normal physiological conditions, how many times per minute do lymph angions typically contract?

• A. 1-3
• B. 5-7
• C. 10-12
• D. 20-22

Answer: (C)

Lymphangions in the collecting lymphatic vessels beat with intrinsic rhythmic contractions to actively propel lymph forward. In a healthy adult at rest, this intrinsic pump cycles about ten to twelve times per minute. This moderate rate provides steady propulsion while allowing enough time for upstream segments to fill between contractions, and it works with the valve system to prevent backflow. External factors like movement and breathing can boost overall lymph flow by enhancing external pumping, but the baseline intrinsic contraction rate remains roughly 10–12 per minute. Rates much slower would not move lymph efficiently; rates much faster would be energetically costly and less effective given filling times.