eezing blood through the mitral valve into the left ventricle. The mitral valve is similar to the tricuspid valve except that it has only two flaps. The left ventricle then contracts sending the blood through another semilunar valve into the aorta. The aorta with its numerous branches then sends the blood throughout the body (140). The heart has two phases, the first is a relaxing/filling phase, and the second is a contracting/emptying phase. The relaxing/filling phase is called the diastole phase. The contracting/pumping phase is called the systole phase (140).The blood and blood vessels are also a necessary component of the circulatory system. The blood vessels form a complicated system of connecting tubes throughout the body. There are three major types of blood vessels. Arteries carry blood from the heart. Veins return blood to the heart. Capillaries are extremely tiny vessels that connect the arteries and the veins (World Book Ci-Cz 559). Blood is the life stream of the human body. This red fluid performs many tasks, and no part of the body can survive without it. Blood supplies cells with the food and oxygen they need, and removes waste from the cells and carries them to organs that remove them from the body, or break them down into harmless substances. In addition the blood fights germs in the body (World Book B 422). Blood has four major parts: plasma, red blood cells, white blood cells, and platelets(423).Plasma is the liquid part of the blood. This straw colored fluid makes up about fifty five to sixty five percent of the total volume of blood. The red and white blood cells and the platelets are all suspended in the plasma. Plasma consists mainly of water. However, it also contains hundreds of other substances, including proteins, digested food, and waste products. The major proteins in plasma are albumin, fibrinogen, and globulin. Albumin helps keep plasma in the blood vessels. If the amount of albumin ...
