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Cardiovascular System

Cardiovascular System. Size of Heart. Average Size of Heart 14 cm long 9 cm wide. Location of Heart. posterior to sternum medial to lungs anterior to vertebral column base lies beneath 2 nd rib apex at 5 th intercostal space lies upon diaphragm. Coverings of Heart .

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Cardiovascular System

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  1. Cardiovascular System

  2. Size of Heart • Average Size of Heart • 14 cm long • 9 cm wide

  3. Location of Heart • posterior to sternum • medial to lungs • anterior to vertebral column • base lies beneath 2nd rib • apex at 5th intercostal space • lies upon diaphragm

  4. Coverings of Heart

  5. Wall of the Heart

  6. Wall of the Heart

  7. Heart Chambers • Right Atrium • receives blood from • inferior vena cava • superior vena cava • coronary sinus • Left Atrium • receives blood from pulmonary veins • Right Ventricle • receives blood from right atrium • Left Ventricle • receives blood from left atrium

  8. Heart Valves

  9. Coronal Sections of Heart

  10. Heart Valves Tricuspid Valve Pulmonary and Aortic Valve

  11. Skeleton of Heart • fibrous rings to which the heart valves are attached

  12. Path of Blood Through the Heart

  13. Path of BloodThrough the Heart

  14. Blood Supply to Heart

  15. Blood Supply to Heart

  16. Angiogram of Coronary Arteries

  17. Heart Actions Atrial Diastole/Ventricular Systole Atrial Systole/Ventricular Diastole

  18. Cardiac Cycle • Atrial Systole/Ventricular Diastole • blood flows passively into ventricles • remaining 30% of blood pushed into ventricles • A-V valves open/semilunar valves close • ventricles relaxed • ventricular pressure increases

  19. Cardiac Cycle • Ventricular Systole/Atrial diastole • A-V valves close • chordae tendinae prevent cusps of valves from bulging too far into atria • atria relaxed • blood flows into atria • ventricular pressure increases and opens semilunar valves • blood flows into pulmonary trunk and aorta

  20. Heart Sounds • Lubb • first heart sound • occurs during ventricular systole • A-V valves closing • Dupp • second heart sound • occurs during ventricular diastole • pulmonary and aortic semilunar valves closing Murmur – abnormal heart sound

  21. Heart Sounds

  22. Cardiac Muscle Fibers • Cardiac muscle fibers form a functional syncytium • group of cells that function as a unit • atrial syncytium • ventricular syncytium

  23. Cardiac Conduction System

  24. Cardiac Conduction System

  25. Muscle Fibers in Ventricular Walls

  26. Electrocardiogram • recording of electrical changes that occur in the myocardium • used to assess heart’s ability to conduct impulses P wave – atrial depolarization QRS wave – ventricular depolarization T wave – ventricular repolarization

  27. Electrocardiogram

  28. Electrocardiogram A prolonged QRS complex may result from damage to the A-V bundle fibers

  29. Cardiac Cycle

  30. Regulation of Cardiac Cycle Autonomic nerve impulses alter the activities of the S-A and A-V nodes

  31. Regulation of Cardiac Cycle Additional Factors that Influence HR • physical exercise • body temperature • concentration of various ions • potassium • calcium • parasympathetic impulses decrease heart action • sympathetic impulses increase heart action • cardiac center regulates autonomic impulses to the heart

  32. Blood Vessels • arteries • carry blood away from ventricles of heart • arterioles • receive blood from arteries • carry blood to capillaries • capillaries • sites of exchange of substances between blood and body cells • venules • receive blood from capillaries • veins • carry blood toward ventricle of heart

  33. Arteries and Arterioles • Arterioles • thinner wall than artery • endothelial lining • some smooth muscle tissue • small amount of connective tissue • helps control blood flow into a capillary • Artery • thick strong wall • endothelial lining • middle layer of smooth muscle and elastic tissue • outer layer of connective tissue • carries blood under relatively high pressure

  34. Walls of Artery and Vein

  35. Arteriole • smallest arterioles only have a few smooth muscle fibers • capillaries lack muscle fibers

  36. Metarteriole connects arteriole directly to venule

  37. Capillaries • smallest diameter blood vessels • extensions of inner lining of arterioles • walls are endothelium only • semipermeable • sinusoids – leaky capillaries

  38. Capillary Network

  39. Regulation of Capillary Blood Flow • Precapillary sphincters • may close a capillary • respond to needs of the cells • low oxygen and nutrients cause sphincter to relax

  40. Exchange in the Capillaries • water and other substances leave capillaries because of net outward pressure at the capillaries’ arteriolar ends • water enters capillaries’ venular ends because of a net inward pressure • substances move in and out along the length of the capillaries according to their respective concentration gradients

  41. Venules and Veins • Venule • thinner wall than arteriole • less smooth muscle and elastic tissue than arteriole • Vein • thinner wall than artery • three layers to wall but middle layer is poorly developed • some have flaplike valves • carries blood under relatively low pressure • serves as blood reservoir

  42. Venous Valves

  43. Characteristics of Blood Vessels

  44. Blood Volumes in Vessels

  45. Arterial Blood Pressure Blood Pressure – force the blood exerts against the inner walls of the blood vessels • Arterial Blood Pressure • rises when ventricles contract • falls when ventricles relax • systolic pressure – maximum pressure • diastolic pressure – minimum pressure

  46. Pulse • alternate expanding and recoiling of the arterial wall that can be felt

  47. Factors That InfluenceArterial Blood Pressure

  48. Control of Blood Pressure Controlling cardiac output and peripheral resistance regulates blood pressure

  49. Control of Blood Pressure If blood pressure rises, baroreceptors initiate the cardioinhibitory reflex, which lowers the blood pressure

  50. Control of Blood Pressure Dilating arterioles helps regulate blood pressure

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