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Cardiovascular II

Cardiovascular II. Outline. Cardiac Cycle Cardiac Output Stroke Volume Heart Rate Fetal Circulation Blood Vessels Blood Flow Blood Pressure Circulatory System Response to Exercise. Cardiac Cycle. Cardiac cycle refers to all events associated with blood flow through the heart.

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Cardiovascular II

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  1. Cardiovascular II

  2. Outline • Cardiac Cycle • Cardiac Output • Stroke Volume • Heart Rate • Fetal Circulation • Blood Vessels • Blood Flow • Blood Pressure • Circulatory System Response to Exercise

  3. Cardiac Cycle • Cardiac cycle refers to all events associated with blood flow through the heart

  4. Phases of the Cardiac Cycle Figure 19.19b

  5. Phases of the Cardiac Cycle Figure 19.19a

  6. Cardiac Output (CO) and Reserve • CO is the amount of blood pumped by each ventricle in one minute • CO = HR x SV

  7. Regulation of Stroke Volume

  8. Factors Affecting Stroke Volume • Preload • Contractility • Afterload

  9. Preload

  10. End Diastolic Volume

  11. Contractility

  12. Figure 12.27

  13. Afterload • The pressure that must be overcome for the ventricles to eject blood • Can be important in people with high blood pressure because it reduces the ability of the ventricles to eject blood

  14. Afterload

  15. Regulation of Heart Rate: Autonomic Nervous System

  16. Chemical Regulation of the Heart • The hormones epinephrine and thyroxine increase heart rate • Intra- and extracellular ion concentrations must be maintained for normal heart function

  17. Ion Imbalances • Hypocalcemia • Hypercalcemia • Hypernatremia • Hyperkalemia

  18. Congestive Heart Failure (CHF) • Congestive heart failure (CHF), caused by: • Coronary atherosclerosis • Increased blood pressure in aorta • Successive myocardial infarcts • Dilated cardiomyopathy (DCM)

  19. Blood Vessels

  20. Generalized Structure of Blood Vessels Figure 20.1b

  21. Blood Flow

  22. Resistance • Resistance – opposition to flow • Measure of the amount of friction blood encounters as it passes through vessels • Generally encountered in the systemic circulation • Referred to as peripheral resistance (PR) • The three important sources of resistance are blood viscosity, total blood vessel length, and blood vessel diameter

  23. Resistance Factors: Viscosity and Vessel Length • Resistance factors that remain relatively constant are: • Blood viscosity – thickness or “stickiness” of the blood • Blood vessel length – the longer the vessel, the greater the resistance encountered

  24. Thought Questions

  25. Radius Effects

  26. Figure 12.21

  27. Blood Pressure (BP) • Force per unit area exerted on the wall of a blood vessel by its contained blood

  28. Systemic Blood Pressure Figure 20.5

  29. Figure 12.30

  30. Figure 12.31

  31. Capillary Blood Pressure

  32. Figure 12.40

  33. Figure 12.41

  34. Figure 12.47

  35. Venous Blood Pressure • Venous BP is steady and changes little during the cardiac cycle • The pressure gradient in the venous system is only about 20 mm Hg • A cut vein has even blood flow; a lacerated artery flows in spurts

  36. Figure 12.45

  37. Thought Question

  38. Control of Blood Pressure • Affecting Total Peripheral Resistance • Affecting Cardiac Output • Affecting Stroke Volume • Affecting Heart Rate • Affecting Total Blood Volume

  39. Figure 12.53

  40. Baroreceptor Activity

  41. Total Peripheral Resistance Local Control

  42. Local Control

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