The document provides an overview of cardiovascular physiology, including: 1. It describes the basic components and regulation of the cardiovascular system, including the heart, vessels, and regulatory mechanisms. 2. It discusses the pulmonary and systemic circulations in terms of pressure, resistance, and flow. 3. It covers the structure and function of the heart as a pump, including cardiac cycle, regulation of contractility, and the Frank-Starling mechanism.

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)

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

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%

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

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)

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

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)

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)

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

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