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Circulatory System Chapter 37 Why do we need one? ◦ Diffusion is too slow for large multicellular organisms. They need a transport system. The heart, blood and vessels make up the human circulatory system. Circulatory System Four-chambered double-pump. Left side pumps oxygen rich blood to the body. Right side pumps oxygen poor blood to the lungs. Heart Made of cardiac muscle. Pacemaker initiates beat. Valves keep blow flowing forward. ◦ Lub-dup sound when they close. The septum divides the heart into right and left sides. The Heart Circulatory Pathways 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 Vessels Section 37-1 Vein Artery Endothelium Arteriole Capillary Venule Connective tissue Connectiv e tissue Smooth muscle Smooth muscle Endothelium Endothelium Valve 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. Blood Liquid part. Mostly water. Carries dissolved carbon dioxide, nutrients, wastes, hormones, antibodies, vitamins, salts and various proteins. Plasma Red blood cells (erythrocytes) ◦ Carry oxygen; most numerous; no nuclei White blood cells (leukocytes) ◦ Fight disease; less numerous; multinucleate Platelets (thrombocytes) ◦ Clot the blood Blood Cells Figure 37-10 Blood Clotting Section 37-2 Break in Capillary Wall Blood vessels injured. Clumping of Platelets Clot Forms Platelets clump at the site and release thromboplastin. Thromboplastin converts prothrombin into thrombin.. Thrombin converts fibrinogen into fibrin, which causes a clot. The clot prevents further loss of blood.. 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. Lymphatic System Section 37-2 Superior vena cava Thymus Heart Thoracic duct Spleen Lymph nodes Lymph vessels The Respiratory System Chapter 37 Cellular respiration – the release of energy stored in food. Takes place in mitochondria. Breathing – exchange of gases. Respiration Basic function is to exchange oxygen for carbon dioxide. Pathway of airflow: ◦ ◦ ◦ ◦ ◦ ◦ ◦ Nose Pharynx Larynx Trachea Bronchi Bronchioles Alveoli Human Respiratory System Figure 37-13 The Respiratory System Section 37-3 Line the entire respiratory passageway. Filters and moistens air. Cilia and Mucus Oxygen and carbon dioxide exchange places by diffusion in both the lungs and the body cells. Gas Exchange Figure 37-14 Gas Exchange in the Lungs Section 37-3 Alveoli Bronchiole Capillary Active phase – chest muscles and diaphragm contract; chest cavity increases in size; air rushes in. Passive phase – muscles relax; chest cavity decreases in size; air is forced out. Breathing Figure 37-15 The Mechanics of Breathing Section 37-3 Air exhale d Air inhale d Rib cage lowers Rib cage rises Diaphragm Diaphragm Inhalation Exhalation Figure 37-15 The Mechanics of Breathing Section 37-3 Air exhale d Air inhale d Rib cage lowers Rib cage rises Diaphragm Diaphragm Inhalation Exhalation