Respiration and excretion

Air travels through the nose, pharynx, trachea, and the bronchi within the lungs. Oxygen is gained by the respiratory system and glucose is gained from the digestive system. Both the oxygen and glucose are transported around the body by the circulatory system. With every breath, we pull oxygen out of the atmosphere. The atmosphere consists of 78% nitrogen, 21% oxygen, and 1% other gases, so the air that we breathe is not all taken into the body. Read More...