Cardiovascular Physiology
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Cardiovascular Physiology Presentation Transcript

  • 1. CARDIOVASCULAR PHYSIOLOGY Dr. Poland Room 3-007, Sanger Hall Phone: 828-9557 E-mail: [email_address]
  • 2. CARDIOVASCULAR SYSTEM HEART (PUMP) VESSELS (DISTRIBUTION SYSTEM) REGULATION AUTOREGULATION NEURAL HORMONAL RENAL-BODY FLUID CONTROL SYSTEM
  • 3. PULMONARY CIRCULATION 1. LOW RESISTANCE 2. LOW PRESSURE (25/10 mmHg) SYSTEMIC CIRCULATION 1. HIGH RESISTANCE 2. HIGH PRESSURE (120/80 mmHg) PARALLEL SUBCIRCUITS UNIDIRECTIONAL FLOW
  • 4. VEINS CAPACITY VESSELS HEART 80 mmHg 120 mmHg SYSTOLE DIASTOLE ARTERIES (LOW COMPLIANCE) CAPILLARIES
  • 5. THE SYSTEMIC CIRCULATION CAPACITY VESSELS
  • 6. NORMAL
  • 7. Na + K + Na + K + -70 mV RESTING THRESHOLD -0 Gradually increasing P Na AUTOMATICITY
  • 8. PURKINJE FIBERS BUNDLE BRANCHES Sino-atrial (SA) node Atrio-ventricular (AV) node
  • 9. INTERCALATED DISC (TIGHT JUNCTION)
  • 10. PACEMAKERS (in order of their inherent rhythm)
    • Sino-atrial (SA) node
    • Atrio-ventricular (AV) node
    • Bundle of His
    • Bundle branches
    • Purkinje fibers
  • 11. MEMBRANE POTENTIAL (mV) -90 0 0 1 2 3 4 TIME PHASE 0 = Rapid Depolarization (inward Na + current) 1 = Overshoot 2 = Plateau (inward Ca ++ current) 3 = Repolarization (outward K + current) 4 = Resting Potential Mechanical Response
  • 12. MEMBRANE POTENTIAL (mV) 0 0 -50 -50 -100 -100 SAN VENTRICULULAR CELL ACTION POTENTIALS 0 1 2 3 4 4 0 3
  • 13. SINGLE VENTRICULAR ACTION POTENTIAL ECG P Q S T R 1 mV Repolarization of ventricles Depolarization of ventricles Depolarization of atria ENDOCARDIAL FIBER EPICARDIAL FIBER ATRIAL FIBER
  • 14. LA RA LL ECG Recordings (QRS Vector pointing leftward, inferiorly & posteriorly) 3 Bipolar Limb Leads: I = RA vs. LA (+)
  • 15. LA RA LL ECG Recordings (QRS Vector pointing leftward, inferiorly & posteriorly) 3 Bipolar Limb Leads: I = RA vs. LA (+) II = RA vs. LL (+)
  • 16. LA RA LL ECG Recordings (QRS Vector pointing leftward, inferiorly & posteriorly) 3 Bipolar Limb Leads: I = RA vs. LA (+) II = RA vs. LL (+) III = LA vs. LL (+)
  • 17. LA RA LL ECG Recordings (QRS Vector pointing leftward, inferiorly & posteriorly) 3 Bipolar Limb Leads: I = RA vs. LA (+) II = RA vs. LL (+) III = LA vs. LL (+) 3 Augmented Limb Leads: aVR = (LA-LL) vs. RA(+)
  • 18. LA RA LL ECG Recordings (QRS Vector pointing leftward, inferiorly & posteriorly) 3 Bipolar Limb Leads: I = RA vs. LA (+) II = RA vs. LL (+) III = LA vs. LL (+) 3 Augmented Limb Leads: aVR = (LA-LL) vs. RA(+) aVL = (RA-LL) vs. LA(+)
  • 19. LA RA LL ECG Recordings (QRS Vector pointing leftward, inferiorly & posteriorly) 3 Bipolar Limb Leads: I = RA vs. LA (+) II = RA vs. LL (+) III = LA vs. LL (+) 3 Augmented Limb Leads: aVR = (LA-LL) vs. RA(+) aVL = (RA-LL) vs. LA(+) aVF = (RA-LA) vs. LL(+)
  • 20. V 1 V 2 V 3 V 4 V 5 V 6 6 PRECORDIAL (CHEST) LEADS Spine Sternum
  • 21. ECG Recordings: (QRS vector---leftward, inferiorly and posteriorly 3 Bipolar Limb Leads I = RA vs. LA(+) II = RA vs. LL(+) III = LA vs. LL(+) 3 Augmented Limb Leads aVR = (LA-LL) vs. RA(+) aVL = (RA-LL) vs. LA(+) aVF = (RA-LA) vs. LL(+) 6 Precordial (Chest) Leads: Indifferent electrode (RA-LA-LL) vs. chest lead moved from position V 1 through position V 6 .
  • 22. LATE DIASTOLE ATRIAL SYSTOLE ISOMETRIC VENTRICULAR CONTRACTION VENTRICULAR EJECTION ISOMETRIC VENTRICULAR RELAXATION THE CARDIAC CYCLE DIASTOLE
  • 23. ISOVOLUMETRIC RELAXATION RAPID INFLOW DIASTASIS ATRIAL SYSTOLE EJECTION ISOVOLUMETRIC CONTRACTION SYSTOLE DIASTOLE SYSTOLE AORTIC PRESSURE ATRIAL PRESSURE VENTRICLE PRESSURE ECG PHONO- CARDIOGAM VOLUME (ml) PRESSURE (mmHg)
  • 24. MEASUREMENT OF CARDIAC OUTPUT THE FICK METHOD: VO 2 = ([O 2 ] a - [O 2 ] v ) x Flow Flow = VO 2 [O 2 ] a - [O 2 ] v Spirometry (250 ml/min) Arterial Blood (20 ml%) Pulmonary Artery Blood (15 ml%) CARDIAC OUTPUT PERIPHERAL BLOOD FLOW VENOUS RETURN PULMONARY BLOOD FLOW
  • 25. CARDIAC OUTPUT (Q) = VO 2 [O 2 ] a - [O 2 ] v 250 ml/min 20 ml% - 15 ml% = = 5 L/min . Q = HR x SV . SV = Q HR . = 5 L/min 70 beats/min = 0.0714 L or 71.4 ml CARDIAC INDEX = Q m 2 body surface area . 5 L/min 1.6 m 2 = = 3.1 L/min/m 2
  • 26. THE HEART AS A PUMP
    • REGULATION OF CARDIAC OUTPUT
      • Heart Rate via sympathetic & parasympathetic nerves
      • Stroke Volume
        • Frank-Starling “Law of the Heart”
        • Changes in Contractility
    • MYOCARDIAL CELLS (FIBERS)
      • Regulation of Contractility
      • Length-Tension and Volume-Pressure Curves
      • The Cardiac Function Curve
  • 27. CARDIAC OUTPUT = STROKE VOLUME x HEART RATE Autoregulation (Frank-Starling “Law of the Heart”) Contractility Sympathetic Nervous System Parasympathetic Nervous System
  • 28. STRIATED MUSCLE CARDIAC MUSCLE SKELETAL MUSCLE - Functional Syncytium - Automaticity - Motor Units - Stimulated by Motor Nerves
  • 29. STRUCTURE OF A MYOCARDIAL CELL Mitochondria Sarcolemma T-tubule SR Fibrils
  • 30. SARCOLEMMA 10% Mitochondria THICK MYOFILAMENT THIN MYOFILAMENT SR Ca ++ T-tubule 20% 80%
  • 31. REGULATAION OF CONTRACTILITY
    • Recruitment of motor units
    • Increase frequency of firing of motor nerves
    • Calcium to trigger contraction
  • 32. INCREASING HEART RATE INCREASES CONTRACTILITY Normal Heart Rate Ca ++ Ca ++ Fast Heart Rate Ca ++ Ca ++ Ca ++ Ca ++
  • 33. SERIES ELASTIC ELEMENTS CONTRACTILE COMPONENT (ACTIVE TENSION) PARALLEL ELASTIC ELEMENTS (PASSIVE TENSION) TOTAL TENSION
  • 34. LENGTH-TENSION CURVE TOTAL TENSION ACTIVE TENSION PASSIVE TENSION OPTIMAL LENGTH (L o ) RESTING LENGTH EQUILIBRIUM LENGTH LENGTH LENGTH TENSION
  • 35. TENSION SARCOMERE LENGTH (  )
  • 36. TENSION MUSCLE LENGTH PASSIVE TENSION ACTAIVE TENSION TOTAL TENSION CARDIAC MUSCLE
  • 37. PRESSURE DIASTOLIC PRESSURE CURVE SYSTOLIC PRESSURE CURVE HEART End Diastolic Volume End Systolic Volume Isovolumetric Phase Isotonic (Ejection) Phase Stroke Volume Pre-load After-load
  • 38. PRESSURE DIASTOLIC PRESSURE CURVE SYSTOLIC PRESSURE CURVE HEART End Diastolic Volume End Systolic Volume Isovolumetric Phase Isotonic (Ejection) Phase Stroke Volume Pre-load After-load INCREASED CONTRACTILITY
  • 39. PRESSURE DIASTOLIC PRESSURE CURVE SYSTOLIC PRESSURE CURVE HEART End Diastolic Volume End Systolic Volume Isovolumetric Phase Isotonic (Ejection) Phase Stroke Volume Pre-load After-load DECREASED CONTRACTILITY
  • 40. PRESSURE DIASTOLIC PRESSURE CURVE SYSTOLIC PRESSURE CURVE HEART End Diastolic Volume End Systolic Volume Isovolumetric Phase Isotonic (Ejection) Phase Stroke Volume Pre-load After-load INCREASED FILLING
  • 41. CARDIAC FUNCTION CURVE STROKE VOLUME DIASTOLIC FILLING Cardiac Output = Stroke Volume x Heart Rate Constant If: Then:  CO reflects  SV Right Atrial Pressure (RAP) reflects Diastolic Filling
  • 42. CARDIAC FUNCTION CURVE CARDIAC OUTPUT (L/min) RAP mmHg 15- 10- 5- -4 0 +4 +8 Volume Pressure THE FRANK- STARLING “LAW OF THE HEART”
  • 43. CARDIAC FUNCTION CURVE CARDIAC OUTPUT (L/min) RAP mmHg 15- 10- 5- -4 0 +4 +8 THE FRANK- STARLING “LAW OF THE HEART” Increased Contractility
  • 44. CARDIAC FUNCTION CURVE CARDIAC OUTPUT (L/min) RAP mmHg 15- 10- 5- -4 0 +4 +8 THE FRANK- STARLING “LAW OF THE HEART” Decreased Contractility
  • 45. CARDIAC FUNCTION CURVE CARDIAC OUTPUT (L/min) RAP mmHg 15- 10- 5- -4 0 +4 +8 THE FRANK- STARLING “LAW OF THE HEART” Increased Heart Rate
  • 46. CARDIAC FUNCTION CURVE CARDIAC OUTPUT (L/min) RAP mmHg 15- 10- 5- -4 0 +4 +8 THE FRANK- STARLING “LAW OF THE HEART” Decreased Heart Rate
  • 47. P 1 P 2 P 1 > P 2 FLOW FLOW =  P R  P = FLOW x R R = mm Hg L/min or ml/sec mm Hg ml/sec Peripheral Resistance Units (PRU)  P FLOW
  • 48. LAMINAR or STREAMLINE FLOW P 2 P 1 P 1 > P 2 -Cone Shaped Velocity Profile -Not Audible with a Stethoscope
  • 49. MEASURING BLOOD PRESSURE TURBULENT FLOW 1. Cuff pressure > systolic blood pressure--No sound. 2. The first sound is heard at peak systolic pressure. 3. Sounds are heard while cuff pressure < blood pressure. 4. Sound disappears when cuff pressure < diastolic pressure.
  • 50. RESISTANCES IN SERIES R T = R A + R C + R V RESISTANCES IN PARALLEL R 1 R 2 R 3 P A P V Flow T = Flow 1 + Flow 2 + Flow 3  P R T  P R 1  P R 2  P R 3 = + + 1 R T 1 R 1 1 R 2 1 R 3 = + + 1 R 1 1 R 2 1 R 3 R T 1 + + =
  • 51. If: R 1 = 2; R 2 = 4; R 3 = 6 PRU’s Then a series arrangement gives: R T = R 1 + R 2 + R 3 R T = 12 PRU’s But a parallel arrangement gives: R T = =1.94 PRU’s 1 1 R 1 1 R 2 1 R 3 + +
  • 52. v =  Pr 2 /8  l Q = v  r 2 Poiseuille's Law  P  r 4 8  l Q =  P R Flow = R = 8  l/  r 4
  • 53. TOTAL PERIPHERAL RESISTANCE TPR = Aortic Pressure - RAP FLOW TPR = 100 - 0 mmHg 83.3 ml/sec (5 L/min) = 1.2 PRU’s SYSTEMIC CIRCULATION: PULMONARY CIRCULATION: Pul. R. = Pul. Art. P. - LAP FLOW Pul. R. = 15 - 5 mmHg 83.3 ml/sec = 0.12 PRU’s
  • 54. VASCULAR COMPLIANCE C =  V  P PRESSURE (mmHg) VOLUME (L) 1 2 3 4 Arteries Veins 100-  Sym  Sym C v = 24 x C a C a = =2.5 ml/mmHg C v = = 60 ml/mmHg 250 ml 100 mmHg 300 ml 5 mmHg  Sym  Sym
  • 55. MEAN CIRCULATORY PRESSURE PRESSURE (mmHg) 7- 1 2 3 4 5 6 Unstressed Volume Stressed Volume VOLUME (L) MCP = 7 mmHg
  • 56. CAPILLARIES
    • Pressure inside is 35 to 15 mmHg
    • 5% of the blood is in capillaries
    • exchange of gases, nutrients, and wastes
    • flow is slow and continuous
  • 57. Metarteriole Arteriole Precapillary Sphincters Capillaries Venule ?
  • 58. VASOMOTION = Intermittent flow due to constriction- relaxation cycles of precapillary shpincters or arteriolar smooth muscle (5 - 10/min) AUTOREGULATION OF VASOMOTION: 1. Oxygen Demand Theory (Nutrient Demand Theory) O 2 is needed to support contraction (closure) 2. Vasodilator Theory Vasodilator substances produced (via  O 2 ) e.g. Adenosine  Heart CO 2  Brain Lactate, H + , K +  Skeletal Muscle 3. Myogenic Activity
  • 59. DIFFUSION BETWEEN BLOOD & INTERSTITIAL FLUID Plasma Proteins BLOOD O 2 CO 2 Glucose INTERSTITIAL FLUID CELL active transport
  • 60. FLUID BALANCE 40- 30- 20- 10- 0- PRESSURE (mmHg) Filtration vs. Reabsorption Outward Forces: 1. Capillary blood pressure (P c = 35 to 15 mmHg) 2. Interstitial fluid pressure (P IF = 0 mmHg) 3. Interstitial fluid colloidal osmotic pressure (  IF = 3 mmHg) TOTAL = 38 to 18 mmHg Inward Force: 1. Plasma colloidal osmotic pressure (  C = 28 mmHg)
  • 61. CAPILLARY FLUID SHIFT P out >  c P out <  c  P c  P c FAVORS FILTRATION FAVORS REABSORPTION PULMONARY CIRCULATION
  • 62. FLUID BALANCE 40- 30- 20- 10- 0- PRESSURE (mmHg) Filtration vs. Reabsorption Filtration Reabsorption Via lymphatics RADIAL FLOW
  • 63. Anchoring Filaments “ PUMP” Compression Smooth muscle contraction 2 - 4 L/day (  125 ml/hr) LYMPHATIC CAPILLARY
  • 64. Effects of gravity on arterial and venous pressures. Each cm of distance produces a 0.77 mmHg change. Sphincters protect capillaries VENOUS PUMP keeps P V < 25 mm Hg Veins Arteries 190 mm Hg 100 mm Hg 0
  • 65. ARTERIES VEINS (RAP)  7 mmHg 7 mmHg   RAP  Art. BP Peripheral Blood Flow HEART CO = PBF
  • 66. C v = 24 x C a  P RAP P v P a  P= P a - P v TPR PBF=TPR (mmHg) (mmHg) (mmHg) (mmHg) (PRU’s) (ml/sec) 7 7 7 0 1.2 0 6 31 25 1.2 20.8 5 55 50 1.2 41.7 4 79 75 1.2 62.5 0 3 103 100 1.2 83.3 (5 L/min) RELATIONSHIP BETWEEN RAP and PBF
  • 67. THE VASCULAR FUNCTION CURVE 10- 5- 0- PBF or VENOUS RETURN (L/min) -4 0 +4 +8 RAP (mmHg)
  • 68. WAYS TO ALTER THE VASCULAR FUNCTION CURVE
    • CHANGE THE MEAN CIRCULATORY PRESSURE
        • CHANGE BLOOD VOLUME
        • CHANGE VENOUS CAPACITY
    • CHANGE TOTAL PERIPHERAL RESISTANCE
  • 69. MEAN CIRCULATORY PRESSURE PRESSURE (mmHg) 7- 1 2 3 4 5 6 Unstressed Volume Stressed Volume BLOOD VOLUME (L)  VOLUME  MCP  VOLUME  MCP Normal Hemorrhage Infusion
  • 70. MEAN CIRCULATORY PRESSURE PRESSURE (mmHg) 7- 1 2 3 4 5 6 Unstressed Volume Stressed Volume BLOOD VOLUME (L) Normal VENOCONSTRICTION
  • 71. MEAN CIRCULATORY PRESSURE PRESSURE (mmHg) 7- 1 2 3 4 5 6 Unstressed Volume Stressed Volume BLOOD VOLUME (L) Normal VENODILATION
  • 72. C v = 24 x C a  P RAP P v P a  P= P a - P v TPR PBF=TPR (mmHg) (mmHg) (mmHg) (mmHg) (PRU’s) (ml/sec) 7 7 7 0 1.2 0 6 31 25 1.2 20.8 5 55 50 1.2 41.7 4 79 75 1.2 62.5 0 3 103 100 1.2 83.3 (5 L/min) 8 8 8 0 1.2 0 7 32 25 1.2 20.8 6 56 50 1.2 41.7 5 80 75 1.2 62.5 4 104 100 1.2 83.3 (5 L/min) 0 3 128 125 1.2 104.2 (6.25 L min RELATIONSHIP BETWEEN RAP and PBF  MCP
  • 73. THE VASCULAR FUNCTION CURVE 10- 5- 0- PBF or VENOUS RETURN (L/min) -4 0 +4 +8 RAP (mmHg)  MCP  MCP  Blood Volume or Venoconstriction  Blood Volume or Venodilation
  • 74. C v = 24 x C a  P RAP P v P a  P= P a - P v TPR PBF=TPR (mmHg) (mmHg) (mmHg) (mmHg) (PRU’s) (ml/sec) 7 7 7 0 1.2 0 6 31 25 1.2 20.8 5 55 50 1.2 41.7 4 79 75 1.2 62.5 0 3 103 100 1.2 83.3 (5 L/min) 7 7 7 0 2.0 0 6 31 25 2.0 12.5 5 55 50 2.0 25.0 4 79 75 2.0 37.5 0 3 103 100 2.0 50.0 (3 L/min) RELATIONSHIP BETWEEN RAP and PBF  TPR
  • 75. THE VASCULAR FUNCTION CURVE 10- 5- 0- PBF or VENOUS RETURN (L/min) -4 0 +4 +8 RAP (mmHg)  TPR  TPR Vasoconstriction Vasodilation
  • 76. CARDIAC & VASCULAR FUNCTION CURVES RAP mmHg 15- 10- 5- -4 0 +4 +8 CARDIAC OUTPUT or PERIPHERAL BLOOD FLOW [Venous Return] (L/min)
  • 77. CHANGES IN CARDIOVASCULAR PERFORMANCE BY ALTERING THE CARDIAC FUNCTION CURVE - CHANGING CONTRACTILITY - CHANGING HEART RATE BY ALTERING THE VASCULAR FUNCTION CURVE - CHANGING MEAN CIRCULATORY PRESSURE Blood Volume Venous Capacity - CHANGING TOTAL PERIPHERAL RESISTANCE
  • 78. MOTOR CORTEX HYPOTHALAMUS VASOMOTOR CENTER PRESSOR AREA DEPRESSOR AREA CARDIOINHIBITORY AREA Vagus HEART Arterioles Veins Adrenal Medulla Baroreceptors Carotid Sinus Aortic Arch Chemoreceptors Carotid Bodies Aortic Bodies Bainbridge Reflex (  Heart Rate) Atrial Receptors Volume Reflex (  Urinary OUTPUT) a.  Vascular Sympathetic Tone b.  ADH Secretion c.  Aldosterone Secretion Chemosensitive Area Glossopharyngeal Nerve Sympathetic Nervous System
  • 79.  BP (Kidney) Renin Angiotensinogen (renin substrate) Angiotensin Aldosterone Kidney  sodium & water retention Vasoconstriction Venoconstriction RENIN-ANGIOTENSIN-ALDOSTERONE MECHANISM
  • 80. HORMONAL REGULATION
    • Epinephrine & Norepinephrine
      • From the adrenal medulla
    • Renin-angiotensin-aldosterone
      • Renin from the kidney
      • Angiotensin, a plasma protein
      • Aldosterone from the adrenal cortex
    • Vasopressin (Antidiuretic Hormone-ADH)
      • ADH from the posterior pituitary
  • 81. Hypothalamic Osmoreceptors  BP via Posterior Pituitary  Vasopressin (ADH) (Atrial Receptors) Vasoconstriction  Water Venoconstriction Retention VASOPRESSIN (ANTIDIURETIC HORMONE) X X
  • 82. RENAL--BODY FLUID CONTROL MECHANISM 8- 7- 6- 5- 4- 3- 2- 1- -8 -7 -6 -5 -4 -3 -2 -1 Uninary Output (x normal) Fluid Intake (x normal) 50 100 150 Normal ARTERIAL BLOOD PRESSURE (mmHg)  P alone All Mechanisms 3 x Normal
  • 83. HYPERTENSION (140/90 mmHg) Secondary Hypertension (10%) [e.g., Pheochromocytoma] Essential Hypertension (90%) - Normal cardiac output - Cardiac hypertrophy [left ventricle] - “Resetting” of the baroreceptors - Thickening of vascular walls ARTERIAL PRESSURE-URINARY OUTPUT THEORY Hypertension causes thickening of vascular walls NEUROGENIC THEORY Thickening of vascular walls causes hypertension TREATMENT: Reduce stress Sympathetic blockers Low sodium diet Diuretics
  • 84. HEMORRHAGE Pressure 7- 1 2 3 4 5 Blood Volume (L)  MCP -4 0 +4 +8 RAP (mmHg) CO or PBF (L/min)  CO  BP
  • 85. CARDIAC & VASCULAR FUNCTION CURVES RAP mmHg 15- 10- 5- -4 0 +4 +8 CARDIAC OUTPUT or PERIPHERAL BLOOD FLOW [Venous Return] (L/min) Response to Hemorrhage  HR & Contractility Venoconstriction (  MCP) Vasoconstriction (  TPR)
  • 86. RESPONSE TO HEMORRHAGE
    •  Sympathetic tone via baroreceptor reflex
      •  Heart rate and contractility
      • Venoconstriction (  MCP)
      • Vasoconstriction (  arterial BP & direct blood to vital organs)
    • Restore Blood Volume
      • Capillary fluid shift (  BP favors reabsorption)
      •  Urinary output (  Arterial BP, ADH, Renin-Angiotensin-Aldosterone)
    • Restore plasma proteins & hematocrit
  • 87. SYNCOPE (FAINTING) Postural syncope ( Blood pooling in the extremities) Vasovagal syncope Carotid sinus syncope
  • 88. SYNCOPE (FAINTING) Blood pooling in the extremities PRESSURE (mmHg) 7- 1 2 3 4 5 6 Unstressed Volume Stressed Volume BLOOD VOLUME (L)  Unstressed Vol.  Stressed Vol.  MCP Normal Syncope (Fainting)
  • 89. SYNCOPE (FAINTING) Blood pooling in the extremities Pressure 7- 1 2 3 4 5 Blood Volume (L)  MCP -4 0 +4 +8 RAP (mmHg) CO or PBF (L/min)  CO  BP
  • 90. CARDIAC & VASCULAR FUNCTION CURVES RAP mmHg 15- 10- 5- -4 0 +4 +8 CARDIAC OUTPUT or PERIPHERAL BLOOD FLOW [Venous Return] (L/min) Response to Syncope (Fainting  HR & Contractility Venoconstriction (  MCP) Vasoconstriction (  TPR)
  • 91. CARDIAC FAILURE
    • CAUSES: Impairment of electrical activity
    • Muscle damage
    • Valvular defects
    • Cardiomyopathies
    • Result of drugs or toxins
    • PROBLEM: Maintaining circulation with a weak pump
    • (  Cardiac output & cardiac reserve;  RAP)
    • SOLUTIONS:  Sympathetic tone via baroreceptor reflex
    • -  Heart rate and contractility
      • -Venoconstriction (  MCP)
      • -Vasoconstriction (  Arterial BP)
      • Fluid retention (  MCP)
      • -Capillary fluid shift
      • -ADH
      • -Renin-angiotensin-aldosterone
  • 92. CARDIAC & VASCULAR FUNCTION CURVES RAP mmHg 15- 10- 5- -4 0 +4 +8 CARDIAC OUTPUT or PERIPHERAL BLOOD FLOW [Venous Return] (L/min) Cardiac Failure Adjustments to Failure SYMPTOMS: Systemic Edema Pulmonary Congestion Enlarged Heart
  • 93. PRESSURE DIASTOLIC PRESSURE CURVE SYSTOLIC PRESSURE CURVE HEART End Diastolic Volume End Systolic Volume Isovolumetric Phase Isotonic (Ejection) Phase Stroke Volume Pre-load After-load CARDIAC FAILURE
  • 94. TEMPERATURE REGUALTION
    • Body Temperature
    • Heat Production
    • Heat Loss
    • Temperature Regulation
      • Heat Exhaustion
      • Heat Stroke
      • Hypothermia
    • Fever
  • 95. COLD WARM
  • 96. Upper limit of survival? Heat stroke Brain lesions Fever therapy Febrile disease and Hard exercise Usual range of normal Temperature regulation seriously impaired Temperature regulation efficient in febrile disease health and work Temperature regulation impaired Temperature regulation lost Lower limit of survival?
  • 97. HEAT PRODUCTION BASAL METABOLIC RATE - Catecholamines -Hyperthyroidism FOOD INTAKE (Specific Dynamic Action) -lasts up to 6 hours after a meal PHYSICAL ACTIVITY -Exercise (20 x BMR) -Shivering (5 x BMR)
  • 98. HEAT LOSS COOL HOT RADIATION CONDUCTION 70%  CONVECTION VAPORIZATION 30%  Insensible Water Loss * * Sweating *
  • 99. SKIN HYPOTHALAMUS Sweating Vasodilation Vasoconstriction Shivering W W W Set point C Warm Receptors Cold Receptors Preoptic Area
  • 100. Interaction Between Peripheral & Central Sensors Cooling the skin raises the set point above which sweating begins. Warm skin--sweating occurs above 36.7  C Cold skin--sweating occurs above 37.4  C The body is reluctant to give off heat (sweat) in a cold environment. Warming the skin lowers the set point below which shivering begins. Cold skin: shivering occurs at 37.1  C Warm skin: shivering occurs at 36.5  C The body is reluctant to produce heat (shiver) in a warm environment.
  • 101. LIMITS TO TEMPERATURE REGULATION Heat Exhaustion: Inadequate water/salt replacement Body temperature may be normal Symptoms: cerebral dysfunction nausea fatique Vasodilaton causing fatigue or fainting Heat Stroke: Temperature regulation lost Symptoms: high body temperature NO sweating dizziness or loss of consciousness Body temperature MUST be lowered!
  • 102. FEVER FEVER = an abnormally high body temperature PYROGEN = a fever producing substance PYROGEN WBC bacterial toxins, leukocytes, viruses, pollen, + monocytes = endogenous pyrogen proteins, dust Arachidonic Acid Prostaglandins Aspirin RAISES THE “SET POINT”
  • 103. Actual Core Temperature Onset of Fever Fever Breaks Reference Temperature or Set Point Shivering Vasoconstriction Sweating Vasodilation