You should notice from the graph that cardiac output (CO) increases as heart rate increases from 30 bpm to 100 bpm. However, CO does not significantly change between 100 bpm to 130 bpm, and beyond 130 bpm CO begins to decline. Explain why CO decreases when the heart rate is increased above 130 bpm in this experiment. How is stroke volume changing along the curve from 30 bpm to 130 bpm? (10pts)
