Breathing, Meditation and Yoga Lab

How the model works: fresh air reaching the air sacs is breaths per minute × (breath depth − 0.15 L dead space). Arterial CO₂ settles toward 40 mmHg × 4.2 ÷ that fresh air value over about half a minute (sped up), and pH comes from the bicarbonate buffer equation with bicarbonate fixed at 24. Heart rate rises with each breath in and falls with each breath out; the size of that swing follows a resonance curve that peaks near 6 breaths per minute and grows a little with deeper breaths. Overbreathing raises the average heart rate a little, and a longer breath out lowers it slightly. The HRV swing is a teaching model, not a measurement.

For predict then watch items, choose an answer first; the picture then plays what happens. For math items, the worked solution builds step by step below the picture. Values are rounded teaching numbers.