ATP is like a charged battery, while ADP is like a dead battery. ATP can be hydrolyzed to ADP and Pi by the addition of water, releasing energy. ADP can be "recharged" to form ATP by the addition of energy, combining with Pi in a process that releases a molecule of water.
What exercise? Post a picture of it.
The atria are chambers<span> in which </span>blood<span> enters the heart. They are located on the anterior end of the heart, with one atrium on each side. The right atrium </span>receives <span>deoxygenated </span>blood<span> from systemic circulation through the </span>superior vena cava<span> and</span>inferior venae cavae<span>.</span>
