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Human Circulation

Human Circulation. A closer look. Contents. Cardiac cycle Maintenance of heartbeat Principles governing blood circulation Cardiovascular disease Lymphatic system Blood composition and function. Cardiac cycle complete sequence of pumping and filling. Electrical activity of the heart.

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Human Circulation

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  1. Human Circulation A closer look

  2. Contents • Cardiac cycle • Maintenance of heartbeat • Principles governing blood circulation • Cardiovascular disease • Lymphatic system • Blood composition and function

  3. Cardiac cycle complete sequence of pumping and filling

  4. Electrical activity of the heart 1 - Sinoatrial node (Pacemaker)2 - Atrioventricular node3 - Atrioventricular Bundle (Bundle of His)4 - Left & Right Bundle branches5 - Bundle Branches 6 - Purkinje fibers AV valves SL valves

  5. Cardiac output • Total volume of blood pumped by the left ventricle per minute • Heart rate (HR)  # beats per minute • Stroke volume (SV) mL • Product gives the cardiac output (Q) • Average adult Q = HR x SV = 70 beats/min x 75 mL/beat = 5.25 L/min • Maximum HR = 200-your age • Training heart rate is 75% MHR • e.g. 200-15 = 185 * 0.75 = 139 beats/min • 20 minutes, 3x a week

  6. Pulse • Stretching of arteries as an effect of heartbeat • Pressure waves moving the artery walls when blood moves into aorta • Usually accurate measure of heart rate • Normal resting pulse is 60-100 bpm • Common pulse points 1. Temporal artery 3. Carotid artery 4. Brachial artery 5. Radial artery

  7. Blood vessel structure

  8. Physical principles governing blood circulation • Blood flow velocity • Aorta (30 cm/s) • Capillaries (0.026 cm/s) • Law of continuity • Volume of flow per second must be constant through the entire pipe • Total cross-sectional area of the capillaries determines flow rate • Blood flow slows down in capillary beds

  9. Osmotic pressure – amount of pressure required to prevent diffusion of water

  10. Blood pressure • Force exerted by blood on walls of vessels • Pressure decreases from arteries to veins • Determined by cardiac output and peripheral resistance by arterioles • Arterial pressure measured by a sphygmomanometer • Systolic/Diastolic (mmHg) • Factors • Heart rate • Blood volume • Resistance of vessels • Viscosity

  11. Blood composition and function

  12. Lymphatic System • Functions • Returns excess body fluid to blood • Transports fats from intestines to blood • Defense • Anatomy • Lymph nodes scattered throughout body (thymus, spleen) • Vessels

  13. Cardiovascular disease • Cardiovascular disease (>50% of all deaths) • Heart attack- death of cardiac tissue due to coronary blockage • Stroke- death of nervous tissue in brain due to arterial blockage • Atherosclerosis: arterial plaques deposit • Arteriosclerosis: plaque hardening by calcium deposits • Hypertension: high blood pressure • Hypercholesterolemia: LDL, HDL

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