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Circulatory System Organsheart, blood vessels,arteries,veins,capillaries Major Function transportation of nutrients,gases and wastes; defense against infection The transport of materials into and out of cells happens by diffusion and active transport. Closed circulatory systems have 3 components: pumpheart, fluid, transporting vessels. . The components of blood are Red blood cells, white blood cells, platelets and plasma. Cellular component Function Characteristics Red Blood Cells Carries oxygen; also Most numerous of carries carbon all blood cells dioxide Round, donut shaped (concave) Lacks nuclei at maturityLife span of approx. 120 days Produced in the bone marrow Contains haemoglobin White Blood Cells Fights bacteria and infection; digests foreign materials Various types Fewer than red blood cellsLarge, irregularshaped nucleiLife span of approx. 10 daysCan squeeze out of the blood vessels Produced in bone marrow, lymph glands, spleen, and thymus Platelet Helps in blood clotting process Irregular shaped cell fragmentsLife span of 510 days Produced in bone marrow 1 The following table describes the major differences between arteries and veins. Arteries Veins Carry blood away from the heart Carry blood towards the heart Strong, thick, muscular walls Thin, nonmuscular walls Carries blood at high pressure, Carries blood at low pressure, 120 mmHg 010 mmHg Has a pulse Has no pulse Carries oxygenated blood (except the pulmonary artery which carries deoxygenated blood) Carries deoxygenated blood (except the pulmonary vein which carries oxygenated blood) Does not contain valves Contains valves Located deep below the surface Many are found close to the surface 2 All mammals have four chambered hearts. The human heart, like all mammalian hearts, is a muscular sac that is divided completely into two halves. Each half is separated from the other half by tissue called the septum. Normally there is no mixing of the blood between these two halves. Each half of the heart is divided into two chambers. Chamber Location Function Left atrium Top left Receives blood from the lungs Right atrium Top right Receives blood from the entire body Left ventricle Bottom left Sends blood to the entire body Right ventricle Bottom right Sends blood to the lungs 3
