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Transcript
Essentials of Human Anatomy & Physiology Elaine N. Marieb Seventh Edition Chapter 11 The Cardiovascular System Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings The Cardiovascular 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 function of the cardiovascular system is to deliver oxygen and nutrients and to remove carbon dioxide and other waste products Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 11.1 The Heart Location Thorax between the lungs • Called the Mediastinum About the size of your fist Less than 1 lb. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide The Heart Figure 11.1 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide The Heart: Coverings Pericardium – a double serous membrane The Heart: Heart Wall (3 Layers) Epicardium Outside layer Connective tissue layer Myocardium Middle layer Mostly cardiac muscle Endocardium Inner layer Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 11.3 External Heart Anatomy Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Figure 11.2a Slide 11.5 The Heart: Chambers Right and left side act as separate pumps Four chambers Atria (Superior) Receiving chambers: Small with thin walls Right atrium Left atrium Ventricles (Inferior) Discharging chambers: Big with thick walls Right ventricle Left ventricle Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 11.6 Blood Vessels Arteries: “Superhighways” Carry blood away from the heart to the body Thick elastic walls to withstand spurts of blood produced by heart contractions • Veins: “Roads” • Thin walled and less elastic • Collect blood after it passes through capillaries and sends blood back to the heart Blood Vessels • Capillaries: “Side-streets and alleys” • Smallest, microscopic vessels • Wastes and nutrients are diffused through capillary membranes into and out of cells Blood Circulation Figure 11.3 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 11.7 Pathway of Blood • Pulmonary Circuit • Right side of heart heart to lungs back to heart • Oxygen poor and carbon dioxide rich blood • Short, low pressure circuit • Right ventricle is not as thick as the left Pathway of Blood • Systemic Circuit • Left side of the heart from heart to body to heart • Oxygen rich and carbon dioxide poor blood • Long, high pressure circuit because it pumps to entire body • Left ventricle is 3x as thick as the right Pathway of Blood 1. Superior/Inferior Vena Cavae 2. Right Atrium 3. Right Ventricle 4. Pulmonary Artery 5. Lungs 6. Pulmonary Veins 7. Left Atrium 8. Left Ventricle 9. Aorta 10. Arteries and Capillaries 11. Veins back to the Heart The Heart: Valves Allow blood to flow in only one direction Four valves Atrioventricular valves – between atria and ventricles Bicuspid valve (left) Tricuspid valve (right) Semilunar valves between ventricle and artery Pulmonary semilunar valve Aortic semilunar valve: guards base of artery Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 11.8 The Heart: Valves Valves open as blood is pumped through Held in place by chordae tendineae (“heart strings”) Close to prevent backflow Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 11.9 Operation of Heart Valves Figure 11.4 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide Electrocardiograms (EKG/ECG) • A graphic picture of cardiac conduction cycle • Three formations “waves” – P wave: Atria depolarize and contract – Small, lasts .08 seconds – QRS complex: ventricles depolarize and contract – Larger, lasts .08 seconds – T wave: ventricles repolarize and relax – More spread out, low height Electrocardiograms (EKG/ECG) (cont.) Figure 8.15B, C Blood Pressure Measurements by health professionals are made on the pressure in large arteries Force exerted by blood against inner walls of blood vessels Systolic – left ventricle; contracting and pushing blood into Aorta causes pressure to peak Diastolic – amount of pressure that the Aorta and Arteries can maintain on reducing blood volume. Ex: 120/70 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide Measuring Arterial Blood Pressure Figure 11.18 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide Variations in Blood Pressure Human normal range is variable Normal 140–110 mm Hg systolic 80–75 mm Hg diastolic Hypotension Low systolic (below 110 mm HG) Often associated with illness Hypertension High systolic (above 140 mm HG) Can be dangerous if it is chronic Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide Heart Sounds “Lub-dub”: closing of the heart valves 1st Sound: “Lub” AV valves closing 2nd Sound: “Dub” Semi-lunar valves closing Heart Murmurs Indicate valve problem (Ex: Leaky Valve) Pacemaker Small mass of cells on the posterior of right atrium just inferior to superior vena cava They “excite” themselves and initiate rhythmic contractions of the heart, the S-A node The Heart: Cardiac Output Cardiac output (CO) Amount of blood pumped by each side of the heart in one minute CO = (heart rate [HR]) x (stroke volume [SV]) Stroke volume Volume of blood pumped by each ventricle in one contraction Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide Cardiac output, cont. • CO = Heart Rate x Stroke Volume – Normal = 5000 ml/min Example: HR= 75 beats/min SV= 70 mL/ beat CO=? CO= 75 x 70 CO= 5250 ml/min= 5.25 L/min • Entire blood supply passes through body once per minute. • CO varies with demands of the body. Cardiac Reserve The ability of the heart to push its cardiac output beyond normal limit depends on the person Most can push their CO up to 4x beyond normal, whereas trained athletes can push their CO up to 7x above normal Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide Sterling’s Law of the Heart The enlargement of the ventricular chambers drives stroke volume and the force of heart contractions The more blood received by the right atrium through the SVC and IVC the stronger the ventricular contraction and the greater the stroke volume and cardiac output Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide