Because flight is metabolically demanding, birds have very efficient systems that help to meet these demands....
Because flight is metabolically demanding, birds have very efficient systems that help to meet these demands. Look at the following list of characteristics and choose those that contribute to the physiological demands of flight. One-way airflow respiration Nucleated red blood cells Air sacs Separate pulmonary systemic circulation Endothermy Slow heart rate Two-cycle lung ventilation Large heart Air capillaries