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CARDIOVASCULAR SYSTEM

CARDIOVASCULAR SYSTEM. PHYSIOLOGY. Pulmonary circulation: Path of blood from right ventricle through the lungs and back to the heart. Systemic circulation: Oxygen-rich blood pumped to all organ systems to supply nutrients.

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CARDIOVASCULAR SYSTEM

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  1. CARDIOVASCULAR SYSTEM PHYSIOLOGY

  2. Pulmonary circulation: • Path of blood from right ventricle through the lungs and back to the heart. • Systemic circulation: • Oxygen-rich blood pumped to all organ systems to supply nutrients. • Rate of blood flow through systemic circulation = flow rate through pulmonary circulation. Fig. 13.9 P. 379

  3. Fig. 13.10b P. 380

  4. Atrioventricular and Semilunar Valves • Atria and ventricles are separated by AV (atrioventricular) valves. • One way valves. • At the origin of the pulmonary artery and aorta are semilunar valves. • One way valves. • Open during ventricular contraction. • Opening and closing of valves occur as a result of pressure differences. Fig. 13.10a P. 380

  5. Cardiac Cycle • Refers to the repeating pattern of contraction and relaxation of the heart. • Systole: • Phase of contraction. • Diastole: • Phase of relaxation.

  6. Fig. 13.12 P. 381

  7. End-diastolic volume - Amount of blood in the ventricles before they contract - also known as preload. Ave = 110 - 130 ml. Stroke volume - Amount of blood ejected from the heart in a single beat.Ave = 70 - 80 ml. End-systolic volume - Amount of blood remaining in the ventricles after they contract. Ave = 40 - 60 ml.

  8. Heart Sounds • Closing of the AV and semilunar valves. • Lub (first sound): • Produced by closing of the AV valves during isovolumetric contraction. • Dub (second sound): • Produced by closing of the semilunar valves when pressure in the ventricles falls below pressure in the arteries. Fig. 13.14 P. 383 • Murmur - Abnormal heart sounds produced by abnormal patterns of blood flow in the heart.

  9. Fig. 13.13 P. 382

  10. Electrical Activity of the Heart • Autorhythmic cardiac muscle cells: • Demonstrates automaticity: • Sinoatrial node functions as the pacemaker. • Spontaneous depolarization (pacemaker potential): • Caused by diffusion of Ca2+ through slow Ca2+ channels. • Cells do not maintain a stable RMP.

  11. Fig. 13.17 P. 385

  12. Electrical Activity of the Heart • Myocardial cells: • have a RMP of –90 mV. • SA node spreads APs to myocardial cells. • When myocardial cell reaches threshold, these cells depolarize.

  13. Fig. 13.18 P. 385

  14. Fig. 13.19 P. 386

  15. Electrical Activity of the Heart • Sinus rhythm - SA node is the pacemaker. Heart rate of 70 - 80 bpm • Ectopic focus: • Pacemaker other than SA node: • If APs from SA node are prevented from reaching these areas, these cells will generate pacemaker potentials. • Junctional rhythm - AV node is the pacemaker. Results in heart rate of 40 - 60 bpm.

  16. Fig. 13.20 P. 386

  17. Excitation-Contraction Coupling in Heart Muscle • Depolarization of myocardial cell stimulates opening of VG Ca2+ channels in sarcolemma. • Ca2+ diffuses down gradient into cell. • Stimulates opening of Ca2+-release channels in SR. • Ca2+ binds to troponin and stimulates contraction (same mechanisms as in skeletal muscle). • During repolarization Ca2+ actively transported out of the cell via a Na+-Ca2+- exchanger.

  18. Electrocardiogram (ECG/EKG) • The body is a good conductor of electricity. • Tissue fluids have a high [ions] that move in response to potential differences. • Electrocardiogram: • Measure of the electrical activityof the heart per unit time. • Potential differences generated by heart are conducted to body surface where they can be recorded on electrodes on the skin.

  19. Electrocardiogram (ECG/EKG) • The ECG helps the physician gain insight into: • The anatomical orientation of the heart • Relative sizes of its chambers • Disturbances of rhythm and conduction • The extent, location, and progress of ischemic damage to the myocardium • The effects of altered electrolyte concentrations • The influence of certain drugs ( i.e. digitalis, calcium channel blockers, and antiarrhythmic agents)

  20. Fig. 13.22 P. 388

  21. Electrocardiogram (ECG/EKG) • P wave: • Atrial depolarization. • QRS complex: • Ventricular depolarization. • Atrial repolarization. • T wave: • Ventricular repolarization. Fig. 13.23 P. 389

  22. Fig. 13.21 P. 387 P-R interval - Length of time between the P wave and the beginning of the QRS complex. Normal range = 0.12 - 0.20 sec.

  23. Fig. 13.21 P. 387 QRS complex - Normal range = 0.06 - 0.10 sec.

  24. Fig. 13.21 P. 387 S-T segment - Length of time during which the entire ventricular myocardium is depolarized. About 0.12 sec. Myocardial ischemia may be detected by changes in this segment.

  25. Fig. 13.31 P. 397

  26. Fig. 13.21 P. 387 Q-T interval - From the beginning of ventricular depolarization through their repolarization. Ave. = 0.36 - 0.40 sec; varies inversely with heart rate.

  27. SINUS RHYTHM

  28. JUNCTIONAL RHYTHM

  29. SECOND DEGREE HEART BLOCK

  30. Cardiac Rate Imbalances Tachycardia - Abnormally fast heart rate (>100 bpm). Bradycardia - Abnormally slow heart rate (<60 bpm).

  31. Fig. 13.32 P. 398

  32. Fig. 13.33 P. 399

  33. Fig. 13.24 P. 390

  34. Fig. 13.25 P. 391

  35. Fig. 13.26 P. 392

  36. Discontinuous

  37. Fig. 13.28 P. 394

  38. Atherosclerosis • The narrowing of the blood vessel lumen. • Responsible (indirectly) for half the deaths in the Western world. • Often begins with a tear in the tunica interna - and progressively builds up fatty plaque. - It usually ends in arteriosclerosis: the death of the tunica media and deterioration of elastic fibers. Fig. 13.30a P. 395

  39. LYMPHATIC SYSTEM Fig. 13.34 P. 400

  40. Fig. 13.35 P. 400

  41. Fig. 13.36 P. 401

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