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The Circulatory System

The Circulatory System. A closed system of the heart and blood vessels The heart pumps blood Blood vessels allow blood to circulate to all parts of the body The functions of the cardiovascular system To deliver oxygen and nutrients to cells and tissues

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The Circulatory System

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  1. The Circulatory System • A closed system of the heart and blood vessels • The heart pumps blood • Blood vessels allow blood to circulate to all parts of the body • The functions of the cardiovascular system • To deliver oxygen and nutrients to cells and tissues • To remove carbon dioxide and other waste products from cells and tissues

  2. Superior vena cava Aorta Parietal pleura (cut) Pulmonary trunk Left lung Pericardium (cut) Apex of heart Diaphragm (c) Figure 11.1c

  3. Left common carotid artery Brachiocephalic trunk Left subclavian artery Superior vena cava Aortic arch Right pulmonary artery Ligamentum arteriosum Ascending aorta Left pulmonary artery Pulmonary trunk Left pulmonary veins Left atrium Right pulmonary veins Auricle of left atrium Right atrium Circumflex artery Right coronary artery in coronary sulcus (right atrioventricular groove) Left coronary artery in coronary sulcus (left atrioventricular groove) Anterior cardiac vein Left ventricle Right ventricle Great cardiac vein Marginal artery Anterior interventricular artery (in anterior interventricular sulcus) Small cardiac vein Inferior vena cava Apex (a) Figure 11.3a

  4. Open vs. closed circulation • Arthropods have open system • Humans have closed system

  5. Systemic Circulation • Left atria to Aorta to arteries to arterioles to capillaries for gas/nutrient exchange • De-oxygenated blood travels through venules to veins to superior/inferior vena cava to right atrium of heart. • Superior and inferior vena cava feed the rt. Atrium.

  6. Pulmonary Circulation • Blood moves from rt. Atrium to rt. Ventricle through the tricuspid valve. • Blood is pumped from the rt. Ventricle through the pulmonary semilunar valve to the pulmonary (trunk) artery to the lungs • Gas exchange occurs in alveoli

  7. Superior vena cava Aorta Left pulmonary artery Right pulmonary artery Left atrium Right atrium Left pulmonary veins Right pulmonary veins Pulmonary semilunar valve Left atrioventricular valve (bicuspid valve) Fossa ovalis Aortic semilunar valve Right atrioventricular valve (tricuspid valve) Left ventricle Right ventricle Chordae tendineae Interventricular septum Inferior vena cava Myocardium Visceral pericardium (b) Frontal section showing interior chambers and valves. Figure 11.3b

  8. Capillary beds of lungs where gas exchange occurs Pulmonary Circuit Pulmonary arteries Pulmonary veins Venae cavae Aorta and branches Left atrium Left ventricle Right atrium Heart Right ventricle Systemic Circuit Capillary beds of all body tissues where gas exchange occurs KEY: Oxygen-rich, CO2-poor blood Oxygen-poor, CO2-rich blood Figure 11.4

  9. Thermoregulation • Characterizes human homeostasis • Endothermic animals regulate body temperature • Arteries carry warm blood from core to body, veins carry cold blood from body. • The vessels run next to each other – counter-current exchange

  10. Heart Cycle • 72 beats per min. • Beat begins in the right atrium at the sinoatrial node (“pacemaker”) • Then to the atrioventricular node • Then to the bundle of His and Purkinje Fibers in the ventricles causing contractions • Systole – during contraction • Diastole - relaxation

  11. Superior vena cava Sinoatrial (SA) node (pacemaker) Left atrium Atrioventricular (AV) node Atrioventricular (AV) bundle (bundle of His) Right atrium Bundle branches Purkinje fibers Interventricular septum Purkinje fibers Figure 11.7

  12. Contents of Blood • Plasma and cells • 3 types of cells • Red blood cells – erythrocytes – carry oxygen • White blood cells – leukocytes – fight infection • Platelets – clotting cells

  13. Clotting • When a blood vessel is damaged, the platelets stick to the vessel wall and send signals • Platlets release protein clotting factors that signal a series of reactions • Prothrobin activator converts prothrombin to thrombin • Thrombin converts fibrinogen to fibrin threads – this strengthens the clot and stops bleeding

  14. 1 Step Vascular spasms occur. • Smooth muscle contracts, causing vasoconstriction. Figure 10.6, step 1

  15. 2 Step Platelet plug forms. • Injury to lining of vessel exposes collagen fibers; • platelets adhere. Collagen fibers • Platelets release chemicals that make nearby • platelets sticky; platelet plug forms. Platelets Figure 10.6, step 2

  16. 3 Step Coagulation events occur. • Clotting factors present in plasma and releasedby injured tissue cells interact with Ca2+ to formthrombin, the enzyme that catalyzes joining offibrinogen molecules in plasma to fibrin. Fibrin • Fibrin forms a mesh that traps red blood cells and platelets, forming the clot. Figure 10.6, step 3

  17. Bone marrow • This is where the blood is made • Located in the center of bone

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