Energy means, it is the ability to do work. Energy metabolism is the process by which energy is produced and transformed. Food provides the source of energy. We need energy to move the muscles in our body to perform activities. The role of energy in the body is to extract oxygen from the air and distribute it into our bloodstream. Energy is needed to circulate blood, but also to breathe and absorb oxygen. I will now explain the physiology of the cardiovascular system and the respiratory system in relation to the body's energy metabolism. The cardiovascular systemThe cardiovascular system is responsible for energy supply. nutrients throughout the body and eliminate gaseous waste from the body. The cardiovascular system is made up of the heart, blood and blood vessels. Arteries, veins and capillaries are the blood vessels of the cardiovascular system. The heart and its role The heart is an organ of the cardiovascular system. The heart is responsible for providing oxygen to all parts of the body. The heart is about the size of a closed fist. It is located right next to the center of the chest. It is surrounded by a protective membrane called the pericardium. The heart is divided into left and right sides. The heart is made of muscles and has walls. It comes in contact to pump blood through blood vessels and throughout your body. The heart beats to maintain blood circulation. The heartbeat directs the cardiac cycle and pumps blood to the body's cells and tissues. Veins supply deoxygenated blood from the body to the right side of the heart. Then the heart returns it to the lungs, where it absorbs more oxygen. Then the oxygen in the blood returns to the left side of your heart and then it pumps it out to the middle of the paper......large diameter to give the least resistance to flow. It has valves to prevent low-pressure blood from flowing backward. Blood circulation There are two types of circulatory systems: pulmonary and systemic. The pulmonary circuit brings blood to the lungs to be oxygenated and then returned to the heart. In the lungs, deoxygenated blood is removed and the oxygen absorbed by hemoglobin in red blood cells. The systemic circuit brings blood throughout the body to return oxygen and deoxygenated blood to the heart. The blood also absorbs nutrients and wastes. The cardiovascular system binds to energy because it circulates oxygen to your body's cells and also circulates nutrients. The cardiovascular system provides oxygen and nutrients to the body's cells and these must generate energy and also make larger molecules. Also the energy needed to pump the heart.