Final answer:
The heart's fuel of choice is oxygen, which it uses for aerobic metabolism to produce ATP for energy. Unlike skeletal muscle, the heart primarily relies on aerobic metabolism. Skeletal muscle can switch between aerobic and anaerobic metabolism, depending on the activity.
Step-by-step explanation:
The fuel of choice of the heart is oxygen. The heart relies on aerobic metabolism, where oxygen is used to produce ATP for energy. Oxygen is brought to the heart through the lungs and is attached to the hemoglobin molecules within the erythrocytes, or red blood cells. The heart also stores oxygen in myoglobin. This aerobic metabolism allows the heart to have sufficient oxygen supply even during peak performance. Compared to skeletal muscle tissue, which can use both aerobic and anaerobic metabolism for fuel, the heart primarily relies on aerobic metabolism. Skeletal muscle can switch between aerobic and anaerobic metabolism depending on the intensity and duration of the activity. Skeletal muscle has a greater capacity for storing glycogen, which can be used for anaerobic metabolism when oxygen supply is limited.