Presentation on theme: "Circulatory System Chapter 37. Circulatory System Why do we need one? ◦Diffusion is too slow for large multicellular organisms. They need a transport."— Presentation transcript:
Blood Vessels Arteries – carry blood away from the heart. ◦Thick, elastic walls. Pulse. ◦Aorta is largest blood vessel in the body. Veins – carry blood back to the heart. ◦Thinner walls and less elastic. ◦Veins have valves. Capillaries - exchange of materials. ◦Walls are one cell thick. ◦Every cell touches a capillary.
Blood Fluid tissue that bathes all cells of the body. Carries nutrients and oxygen to the cells and wastes and carbon dioxide away from the cells. Helps regulate body temperature. Some components help fight disease. Composed of plasma and cells.
Plasma Liquid part. Mostly water. Carries dissolved carbon dioxide, nutrients, wastes, hormones, antibodies, vitamins, salts and various proteins.
Blood Cells Red blood cells (erythrocytes) ◦Carry oxygen; most numerous; no nuclei White blood cells (leukocytes) ◦Fight disease; less numerous; multinucleate Platelets (thrombocytes) ◦Clot the blood
Section 37-2 Figure 37-10 Blood Clotting Break in Capillary Wall Blood vessels injured. Clumping of Platelets Platelets clump at the site and release thromboplastin. Thromboplastin converts prothrombin into thrombin.. Clot Forms Thrombin converts fibrinogen into fibrin, which causes a clot. The clot prevents further loss of blood..
Lymphatic System Network of vessels that return fluid back to the blood. Lymph nodes filter bacteria and microbes from the fluid. The thymus gland in the neck matures T lymphocytes. The spleen removes damaged blood cells from circulation.