<span>The largest of these is the aorta, or main artery, which carries nutrient-rich blood away from the heart. Another important vessel is the pulmonary artery which connects the heart with the lungs as part of the pulmonary circulation system.</span>
Cellular respiration<span> is a set of metabolic reactions and processes that take place in the </span>cells<span> of organisms to convert biochemical energy from nutrients into ATP, and then releases waste products.</span>
Lactase helps digest lactose which is a sugar found in milk and other dairy products.