Cardiac anatomy and physiology


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Cardiac anatomy and physiology

  1. 1. Cardiac Anatomy and Physiology Iris Ken R. Rico, OTRP Lecturer
  2. 3. <ul><li>OUTLINE: </li></ul><ul><li>Introduction </li></ul><ul><li>Functions of the Heart </li></ul><ul><li>Size, Form, and Location of the Heart </li></ul><ul><li>Anatomy of the Heart </li></ul><ul><ul><li>Pericardium </li></ul></ul><ul><ul><li>External Anatomy </li></ul></ul><ul><ul><li>Heart Chambers and Internal Anatomy </li></ul></ul><ul><ul><ul><li>Right and Left Atria </li></ul></ul></ul><ul><ul><ul><li>Right and Left Ventricles </li></ul></ul></ul><ul><ul><li>Heart Valves </li></ul></ul><ul><ul><ul><li>Atrioventricular valves </li></ul></ul></ul><ul><ul><ul><ul><li>Tricupsid valve </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Mitral valve </li></ul></ul></ul></ul><ul><ul><ul><li>Semi-lunar valves </li></ul></ul></ul><ul><ul><ul><ul><li>Aortic valve </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Pulmonic valve </li></ul></ul></ul></ul><ul><ul><li>Route of Blood Flow Through the Heart </li></ul></ul><ul><ul><li>Blood Supply to the Heart </li></ul></ul><ul><li>Histology of the Heart </li></ul><ul><ul><li>Heart Wall </li></ul></ul><ul><ul><li>Cardiac Muscle </li></ul></ul>
  3. 4. <ul><li>Electrical Activity of the Heart </li></ul><ul><ul><li>Action Potentials in Cardiac Muscle </li></ul></ul><ul><ul><li>Conduction System of the Heart </li></ul></ul><ul><ul><li>Electrocardiogram </li></ul></ul><ul><li>Cardiac Cycle </li></ul><ul><li>Heart sounds </li></ul><ul><li>Regulation of Heart Function </li></ul><ul><ul><li>Intrinsic Regulation of the Heart </li></ul></ul><ul><ul><li>Extrinsic Regulation of the Heart </li></ul></ul><ul><li>Control of the Heart by Sympathetic and Parasympathetic Nerves </li></ul><ul><ul><li>Excitation of the Heart by Sympathetic Nerves </li></ul></ul><ul><ul><li>Parasympathetic (Vagal) Stimulation of the Heart </li></ul></ul><ul><li>Effect of Potassium and calcium Ions on heart Function </li></ul><ul><ul><li>Effect of Potassium Ions </li></ul></ul><ul><ul><li>Effect of Calcium Ions </li></ul></ul><ul><li>Effect of Temperature on Heart Function </li></ul><ul><li>Systems Pathology </li></ul><ul><ul><li>Effects of Aging on the Heart </li></ul></ul>
  4. 5. FUNCTIONS OF THE HEART <ul><li>Generating blood pressure. </li></ul><ul><li>Routing blood. </li></ul><ul><li>Ensuring one-way blood flow. </li></ul><ul><li>Regulating blood supply. </li></ul>
  5. 6. <ul><li>SIZE, FORM, AND LOCATION OF THE HEART </li></ul>
  6. 7. <ul><li>Blunt cone and size of a closed fist </li></ul><ul><li>> age 65 </li></ul><ul><li>Location </li></ul><ul><li>Mediastinum = heart, trachea, esophagus </li></ul><ul><li>Knowledge on the shape and location of the heart </li></ul><ul><li>Lies obliquely in the mediastinum, with its base directed posteriorly and slightly superiorly and the apex directed anteriorly and slightly inferiorly </li></ul><ul><li>Apex = directed to the left, approximately 2/3 pf the heart’s mass, lies left of the midline of the sternum, deep to the left 5th ICS, approximately 7-9 cm to the left of the sternum near the midclavicular line </li></ul><ul><li>Base = located deep to the sternum and extends to the level of the 2nd ICS </li></ul><ul><li>Size/dimensions </li></ul><ul><li>At rest and during exercise </li></ul>
  7. 10. <ul><li>ANATOMY OF THE HEART </li></ul>
  8. 12. Pericardium <ul><li>Pericardial cavity </li></ul><ul><li>Pericardium or pericardial sac </li></ul><ul><ul><li>Two layers: </li></ul></ul><ul><ul><ul><li>Fibrous pericardium </li></ul></ul></ul><ul><ul><ul><li>Serous pericardium </li></ul></ul></ul><ul><li>Parietal pericardium </li></ul><ul><li>Visceral pericardium or Epicardium </li></ul><ul><li>Pericardial fluid </li></ul>
  9. 14. External Anatomy <ul><li>Atria (R/L) </li></ul><ul><li>Ventricles </li></ul><ul><li>Coronary sulcus </li></ul><ul><li>Anterior ventricular sulcus </li></ul><ul><li>Posterior interventicular sulcus </li></ul><ul><li>6 veins that carry blood to the heart </li></ul><ul><li>Pulmonary trunk and aorta </li></ul>
  10. 16. Heart Chambers and Internal Anatomy <ul><li>Right (pulmonic) pump: circulates blood to the lungs </li></ul><ul><li>Left (systemic) pump: circulates blood to the body </li></ul>
  11. 17. Right Atrium <ul><ul><li>Thin muscle wall </li></ul></ul><ul><ul><li>Most blood flow into the right atrium during inspiration when RA pressure drops below that in IVC and SVC (higher to lower pressure) </li></ul></ul><ul><ul><li>High flow; low pressure system </li></ul></ul><ul><ul><li>Function: Receives unoxygenated blood from the venous system </li></ul></ul><ul><ul><li>Inflow: Superior and inferior vena cava </li></ul></ul><ul><ul><li>Outflow: Tricuspid valve </li></ul></ul>
  12. 19. Left Atrium <ul><ul><li>Slightly thicker than the right atrium </li></ul></ul><ul><ul><li>Breathing does not affect filling </li></ul></ul><ul><ul><li>Function: Receives oxygenated blood from the lungs </li></ul></ul><ul><ul><li>Inflow: 4 Pulmonic veins </li></ul></ul><ul><ul><li>Outflow: Mitral (Bicuspid) valve </li></ul></ul><ul><ul><li>Normal filling pressure: 4-12mmHg </li></ul></ul>
  13. 21. Right Ventricle <ul><ul><li>Function: Delivers unoxygenated blood to the lungs </li></ul></ul><ul><ul><li>Inflow: Tricuspid valve </li></ul></ul><ul><ul><li>Outflow: Pulmonic valve </li></ul></ul><ul><ul><li>Four muscular bands: </li></ul></ul><ul><ul><ul><li>Infundibulum septum </li></ul></ul></ul><ul><ul><ul><li>Parietal band </li></ul></ul></ul><ul><ul><ul><li>Septal band </li></ul></ul></ul><ul><ul><ul><li>Moderator band </li></ul></ul></ul><ul><ul><li>Normal systolic pressure: 15– 28mmHg </li></ul></ul><ul><ul><li>End diastolic pressure: 0-8mmHg </li></ul></ul>
  14. 23. Left Ventricle <ul><ul><li>Function: Delivers oxygenated blood to the body </li></ul></ul><ul><ul><li>Inflow: Mitral valve </li></ul></ul><ul><ul><li>Outflow: Aortic valve </li></ul></ul><ul><ul><li>Normal systolic pressure: 120mmHg (100-140) </li></ul></ul><ul><ul><li>End diastolic pressure: 4-12mmHg </li></ul></ul>
  15. 25. Cardiac Skeleton <ul><li>Anulus fibrosus – firm anchor to which most of the heart’s muscles and valves are attached </li></ul><ul><ul><li>Gives structure to the heart and acts as an insulator to ensure that electrical impulses move through the AV node and bundle only </li></ul></ul><ul><ul><li>Consists of tough fibrous rings surrounding the AV valves, and the bases of the aortic and the pulmonary trunks connected by the tendon of the conus </li></ul></ul>
  16. 26. Heart Valves <ul><li>Atrioventricular valve </li></ul><ul><ul><li>Tricuspid valve </li></ul></ul><ul><ul><li>Bicuspid or mitral valve </li></ul></ul><ul><li>Semilunar valve </li></ul><ul><ul><li>Aortic valve </li></ul></ul><ul><ul><li>Pulmonary valve </li></ul></ul>
  17. 30. <ul><li>Papillary muscles – contract when ventricle walls contract </li></ul><ul><ul><li>Do not help the valves to close </li></ul></ul><ul><ul><li>Pull vanes inward toward the ventricles to prevent bulging too far backward toward the atria </li></ul></ul><ul><li>Chordae tendinae – connect valve leaflet to papillary muscles in the ventricles </li></ul>
  18. 32. Route of Blood Flow through the Heart
  19. 34. Blood Supply to the Heart
  20. 35. Coronary Arteries <ul><li>Left coronary artery – originates from the left side of the aorta </li></ul><ul><ul><li>3 branches: </li></ul></ul><ul><ul><ul><li>Anterior interventricular artery – lies in the anterior interventricular sulcus </li></ul></ul></ul><ul><ul><ul><li>Circumflex artery – extends around the coronary sulcus on the left to the posterior surface of the heart </li></ul></ul></ul><ul><ul><ul><li>Left marginal artery – extends inferiorly along the lateral wall of the left coronary artery </li></ul></ul></ul>
  21. 36. <ul><li>Right coronary artery – originates on the right side of the aorta and extends around the coronary sulcus on the right to the posterior interventricular sulcus </li></ul><ul><li>2 branches: </li></ul><ul><ul><ul><li>Posterior interventricular artery – lies in the posterior interventricular sulcus </li></ul></ul></ul><ul><ul><ul><li>Right marginal artery – extends inferiorly along the lateral wall of the right ventricle </li></ul></ul></ul><ul><li>Resting person – heart gives approximately 70% of its oxygen </li></ul>
  22. 39. Cardiac Veins <ul><li>Drain blood form the cardiac muscle </li></ul><ul><li>Pathways nearly parallel to the coronary arteries and most drain blood into the coronary sinus (large vein located within the coronary sulcus on the posterior aspect of the heart) </li></ul><ul><li>Some drain directly into the right atrium </li></ul>
  24. 42. Heart Wall <ul><li>Epicardium or visceral pericardium </li></ul><ul><li>Myocardium </li></ul><ul><li>Endocardium </li></ul><ul><li>Trabeculae carnea </li></ul>
  25. 44. Cardiac Muscle <ul><li>Cardiac muscle cell </li></ul><ul><li>3 major types of cardiac muscle </li></ul><ul><ul><li>Atrial muscle </li></ul></ul><ul><ul><li>Ventricular muscle </li></ul></ul><ul><ul><li>Excitatory and conducive muscle fibers </li></ul></ul><ul><ul><ul><li>Specialized fibers that contract only feebly because of few contractile fibrils </li></ul></ul></ul>
  26. 45. Physiologic Anatomy
  28. 48. Action Potentials in Cardiac Muscle <ul><ul><li>105 millivolts </li></ul></ul><ul><ul><li>After the initial spike, the membrane remains depolarized for about ___ second in atrial muscle and ____ second in ventricular muscle exhibiting a plateau followed by repolarization </li></ul></ul>
  29. 49. <ul><li>Depolarization phase </li></ul><ul><li>Early repolarization phase </li></ul><ul><li>Plateau phase </li></ul><ul><li>Final repolarization phase </li></ul>
  30. 50. What causes the long action potential and plateau? <ul><li>2 types of channels </li></ul><ul><ul><li>Fast sodium channels </li></ul></ul><ul><ul><li>Slow calcium channels </li></ul></ul><ul><li>Immediately after the onset of action potential, permeability of cardiac muscle for potassium ions decreases about fivefold </li></ul>
  31. 52. Conduction System of the Heart <ul><li>Sinoatrial node </li></ul><ul><li>Atrioventricular node </li></ul><ul><li>Atrioventricular bundle </li></ul><ul><li>Right and left bundle branches </li></ul><ul><li>Purkinje fibers </li></ul>
  32. 53. Sinoatrial node <ul><ul><li>Pacemaker of the Heart </li></ul></ul><ul><ul><li>Is a small flattened, ellipsoidal strip of specialized muscle about ___ millimeters wide, ___millimeters long, and ___ millimeter thick </li></ul></ul><ul><ul><li>Located in the superior posterolateral wall of the right atrium immediately below and slightly lateral to the opening of the SVC </li></ul></ul><ul><ul><li>Generates the normal rhythmical impulse </li></ul></ul><ul><ul><li>Sinus nodal fibers connect directly with the atrial muscle fibers </li></ul></ul><ul><ul><li>Ectopic pacemaker </li></ul></ul><ul><ul><li>Stokes-Adam syndrome </li></ul></ul>
  33. 54. Atrioventricular node <ul><ul><li>Located in the posterior wall of the right atrium immediately behind the tricuspid valve and adjacent opening of the coronary sinus </li></ul></ul><ul><ul><li>Delay transmission of impulse from atria to ventricles to allow time for atria to empty their blood into the ventricles before ventricular contraction begins </li></ul></ul><ul><ul><li>Discharge at an intrinsic rhythmical rate </li></ul></ul>
  34. 55. Atrioventricular bundle <ul><ul><li>Composed of multiple small fascicles passing through the fibrous tissue separating the atria from the ventricles </li></ul></ul><ul><ul><li>Delay from A-V node to bundle is about 0.13 second </li></ul></ul>
  35. 56. Right and left bundle branches
  36. 57. Purkinje fibers <ul><ul><li>Very large fibers </li></ul></ul><ul><ul><li>Transmit velocity about 6 times that in usual ventricular muscle and 150 times that in some A-V nodal fibers </li></ul></ul><ul><ul><li>Rapid transmission of action potential </li></ul></ul><ul><ul><li>Discharge at an intrinsic rhythmical rate </li></ul></ul>
  37. 59. Electrocardiogram <ul><li>Recording device that detect the small electrical changes resulting form the action potentials in all of the cardiac muscle cells </li></ul>
  38. 60. Normal ECG consists of: <ul><ul><li>P wave </li></ul></ul><ul><ul><ul><li>Atrial depolarization </li></ul></ul></ul><ul><ul><li>QRS complex </li></ul></ul><ul><ul><ul><li>Ventricular depolarization </li></ul></ul></ul><ul><ul><li>T wave </li></ul></ul><ul><ul><ul><li>Ventricular repolarization </li></ul></ul></ul>
  39. 61. <ul><li>PQ/PR interval – beginning of the P wave and beginning of QRS complex </li></ul><ul><ul><li>Atria contract and begin to relax </li></ul></ul><ul><ul><li>End – ventricle begin to depolarize </li></ul></ul><ul><ul><li>Normal PQ interval is 0.16 second sometimes called the PR interval cause the Q wave is frequently absent </li></ul></ul><ul><li>QT interval – beginning of the QRS complex to the end of the T wave </li></ul><ul><ul><li>Represents the length of time required for ventricular depolarization and repolarization </li></ul></ul><ul><ul><li>0.35 second </li></ul></ul>
  41. 64. <ul><li>Beginning of one heartbeat to the beginning of the next beat </li></ul><ul><li>Includes systole, diastole, and a short pause called diastasis cordis </li></ul><ul><li>Duration depends on heart rate </li></ul><ul><li>Entire heart rests for 0.4 seconds </li></ul>
  42. 65. Components of cardiac event: <ul><ul><li>Ventricular systole </li></ul></ul><ul><ul><ul><li>Isometric contraction phase </li></ul></ul></ul><ul><ul><ul><li>Rapid ejection phase </li></ul></ul></ul><ul><ul><ul><li>Slow ejection phase </li></ul></ul></ul><ul><ul><li>Ventricular diastole </li></ul></ul><ul><ul><ul><li>Isometric interval phase </li></ul></ul></ul><ul><ul><ul><li>Atrial systole phase </li></ul></ul></ul><ul><ul><ul><li>Slow ventricular filling phase </li></ul></ul></ul><ul><ul><ul><li>Rapid ventricular filling phase </li></ul></ul></ul>
  43. 66. Isometric contraction phase <ul><ul><ul><ul><li>Isovolumetric contraction phase = all valves closed and no ejection of blood </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Beginning of ventricular contraction </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Increase in pressure = AV close </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Atria fills with blood </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Tension is increasing in the muscle but no shortening of the muscle fibers is occuring </li></ul></ul></ul></ul>
  44. 67. Rapid ejection phase <ul><ul><ul><ul><li>Left ventricular pressure exceeds 80mmHg and right ventricular pressure exceeds 8mmHg = aortic and pulmonic valves open </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Pouring of blood from atria to ventricles </li></ul></ul></ul></ul><ul><ul><ul><ul><li>70% emptied during first third of ejection period </li></ul></ul></ul></ul>
  45. 68. Slow ejection phase <ul><ul><ul><ul><li>Remaining 30% of blood in the ventricle is emptied during 2/3 of ejection phase </li></ul></ul></ul></ul>
  46. 69. Isometric interval phase <ul><ul><ul><ul><li>A.K.A. - Isovolumetric interval phase </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Relaxation phase and is the beginning of diastole </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Ventricular pressure lower than in the aorta and pulmonary artery = momentary backflow of blood and closure of semilunar valves (2nd heart sound) </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Ventricular pressure drops to 00mmHg </li></ul></ul></ul></ul>
  47. 70. Rapid ventricular filling phase <ul><ul><ul><ul><li>Ventricular pressure falls below atrial pressure = AV valves open, blood rushes rapidly from atria to ventricles </li></ul></ul></ul></ul>
  48. 71. Slow ventricular filling phase <ul><ul><ul><ul><li>Diastasis or the last part of diastole </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Small amount drain from the lungs and peripheral circulation into the atria and added to ventricles </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Towards ends= depolarization of atria begins </li></ul></ul></ul></ul>
  49. 72. Atrial systole phase <ul><ul><ul><ul><li>Atrial contraction or atrial kick </li></ul></ul></ul></ul><ul><ul><ul><ul><li>25% more blood to the ventricle during last phase of ventricular systole </li></ul></ul></ul></ul>
  50. 74. HEART SOUNDS
  51. 75. <ul><li>Stethoscope </li></ul><ul><li>First heart sound – “Lubb” </li></ul><ul><ul><li>Lower pitch </li></ul></ul><ul><ul><li>Occurs at the beginning of ventricular systole and results form closure of the AV valves </li></ul></ul><ul><li>Second heart sound - “Dub” </li></ul><ul><ul><li>Occurs at the beginning of ventricular systole and results from closure of semilunar valves </li></ul></ul><ul><li>Murmurs </li></ul>
  53. 77. <ul><li>Cardiac output (CO) – volume of blood puped by either ventricle of the heart each minute </li></ul><ul><ul><li>CO = SV x HR </li></ul></ul><ul><li>Stroke volume (SV) – volume of blood pumped per ventricle each time the heart contracts </li></ul><ul><li>Heart rate – number of times the heart contracts each minute </li></ul><ul><li>Resting conditions – 72 beats/min , SV = 70 mL/beat, CO – 5040 mL/min </li></ul><ul><li>Athletes - higher SV and lower HR </li></ul>
  54. 78. 4 Interrelated factors that govern cardiac output: <ul><li>Preload </li></ul><ul><li>Afterload </li></ul><ul><li>Contractility </li></ul><ul><li>Heart rate </li></ul>
  55. 79. Preload <ul><ul><li>Ventricular filling </li></ul></ul><ul><ul><ul><li>Influenced by the total volume of circulating blood </li></ul></ul></ul><ul><ul><ul><li>> venous return > stretch of myocardial fibers </li></ul></ul></ul><ul><ul><ul><li>FRANK-STARLING’S LAW = the greater the myocardial stretch, the greater the force of contraction </li></ul></ul></ul>
  56. 80. Afterload <ul><ul><li>Resistance to ejection of blood </li></ul></ul><ul><ul><ul><li>Amount of tension the ventricles must develop to eject the blood through the semilunar valves </li></ul></ul></ul><ul><ul><ul><li>Resistance against which the heart must pump the blood to all parts of the body </li></ul></ul></ul><ul><ul><ul><li>Factors causing higher that normal resistance: </li></ul></ul></ul><ul><ul><ul><ul><li>Systemic and pulmonary arterioles </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Increased blood viscosity </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Pulmonary valve stenosis </li></ul></ul></ul></ul>
  57. 81. Contractility <ul><ul><ul><li>Refers to changes in the force of myocardial contraction and is a function of the interaction between the contractile elements </li></ul></ul></ul><ul><ul><ul><li>Depends on: </li></ul></ul></ul><ul><ul><ul><ul><li>Amount of contractile proteins </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Presence of ATP and calcium </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Sympathetic stimulation </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Pharmacologic agents </li></ul></ul></ul></ul>
  58. 82. Heart Rate <ul><ul><ul><li>Influenced by many factors: </li></ul></ul></ul><ul><ul><ul><ul><li>Exercise </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Person’s physical size </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Age </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Gender differences </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Hypotension and hypertension </li></ul></ul></ul></ul><ul><ul><ul><ul><li>ANS via sympathetic and parasympathetic branches </li></ul></ul></ul></ul>
  59. 83. Extrinsic Regulation of the Heart <ul><ul><li>Refers to mechanisms external to the heart, such as either hormonal or nervous regulation </li></ul></ul><ul><li>Baroreceptors </li></ul><ul><ul><li>Plays an important role in regulating the function of the heart </li></ul></ul><ul><ul><li>Are stretch receptors that monitor pressure in the aorta and in the wall of the internal carotid arteries, which carry blood to the brain </li></ul></ul><ul><ul><li>Changes in blood pressure result in changes in the stretch of the walls of the blood vessels leading to changes in the frequency of action potentials produced by baroreceptors </li></ul></ul><ul><li>Chemoreceptors </li></ul><ul><li>Emotions influence heart function by increasing sympathetic stimulation of the heart in response to exercise, excitement, anxiety, or anger and by increasing parasympathetic stimulation in response to depression </li></ul><ul><li>Alterations in body fluid levels of cardon dioxide, pH, and ion concentrations, as well as changes in body temperature, influence heart function </li></ul>
  60. 84. Control of the Heart by Sympathetic and Parasympathetic Nerves <ul><li>Excitation of the Heart by Sympathetic Nerves </li></ul><ul><ul><li>Strong = increase heart rate from the normal 70 beats for minute to 180 to 200 and rarely 250 beats per minute </li></ul></ul><ul><ul><li>Increase force of contraction, increasing the volume of blood pumped and increasing the ejection pressure </li></ul></ul><ul><ul><li>Increases cardiac output tp twofold to threefold </li></ul></ul>
  61. 85. <ul><li>Parasympathetic (Vagal) Stimulation of the Heart </li></ul><ul><ul><li>Strong = stop heartbeat for a few seconds, but then the heart usually escapes and beats at a rate of 20 to 40 beats per minute, 40 % normal </li></ul></ul><ul><ul><li>Decrease the strength of heart contraction by 20 to 30% </li></ul></ul><ul><ul><li>Decrease heart rate rather than to decrease greatly the strength of heart contraction </li></ul></ul>
  62. 87. Effect of Potassium and Calcium Ions on heart Function <ul><li>Effect of Potassium Ions </li></ul><ul><ul><li>Excess potassium </li></ul></ul><ul><ul><li>Large quantities = block conduction from atria to ventricles through the A-V bundle </li></ul></ul><ul><ul><li>Elevation to only 8 to 12 mEq/L </li></ul></ul><ul><li>Effect of Calcium Ions </li></ul><ul><ul><li>Opposite the effect of potassium ions </li></ul></ul>
  63. 88. Effect of Temperature on Heart Function <ul><li>Increased temperature = increased heart rate </li></ul><ul><li>Decreased temperature = decreased heart rate </li></ul><ul><li>Near death due to hypothermia </li></ul><ul><li>Heat </li></ul><ul><li>Contractile strength = enhanced temporarily by a moderate increase in temperature, but prolonged elevation exhausts metabolic system of the heart and causes weakness </li></ul>
  64. 89. EFFECTS OF AGING ON THE HEART <ul><li>Gradual changes in function </li></ul><ul><li>Age 70 = decreases approximately 1/3 </li></ul><ul><li>Hypertrophy of the left ventricle = increase pressure in the aorta against which the left ventricle must pump </li></ul><ul><li>Greater amount time to contract and relax, decrease in maximum heart rate </li></ul><ul><li>Changes in connective tissue of the heart valves = less flexible and calcium deposits develop </li></ul><ul><li>Increased in cardiac arrhythmias </li></ul><ul><li>Development of CAD and heart failure </li></ul><ul><li>Aerobic exercise </li></ul>
  65. 90. Thank You!