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Heart Rate, Blood Pressure, and Exercise Blood Pressure • Made up of two numbers: – systolic blood pressure – diastolic blood pressure. • Written as: Systolic/Diastolic • Spoken as: Systolic Over Diastolic • Measured in mmHg Measuring Blood Pressure • Sphygmomanometer and stethoscope • Normally, inflate cuff to 180 mmHg –Allow pressure to drop at a rate of 3 mmHg/second • Three Conditions –No Flow –Turbulent Flow –Laminar Flow Cardiac Output and Exercise Q = HR x SV • Q is cardiac output (L/min) •HR is heart rate (beats/min) • SV is stroke volume (ml/beat) • Cardiac output must increase in exercise to meet the metabolic demand of the active tissues. Total Peripheral Resistance • Describes the resistance in vessels • Change it via physiological response or by physical measures • Vasoconstrict or Vasodilate in response to exercise. – Active Skeletal muscles: Vasodilate – Non essential organs & Non-active skeletal muscles: Vasoconstrict Systolic Blood Pressure • Refers to the arterial pressure during the contraction phase of the heart • Corresponds with the onset of turbulent flow through the arteries • Pressure at first Korotkoff sound (a beating sound with each heart beat) • Average value is around 120 mmHg • Reflects Cardiac Output, but is not equal to it Diastolic Blood Pressure • Refers to the arterial pressure during the relaxation phase of the heart • Corresponds with the onset of laminar flow through the arteries • Pressure at last Korotkoff sound (a beating sound with each heart beat) • Average value is around 80 mmHg • Reflects total peripheral resistance, but is not equal to it Blood Pressure Must Be Regulated • Low Blood Pressure Blood will not reach all tissues Specifically those where gravity is acting against flow Most importantly the brain • High Blood Pressure – Heart is placed under great stress – Excess plasma leakage – At the extreme, capillaries burst Rate Pressure Product RPP = HR x Systolic BP / 100 • Has no units • An estimation of the total work of the heart • Also known as the double product Two Types of Exercise • Dynamic – Involves repetitive motions – What we typically think of as exercise • Static – A held position with little or not muscle movement – Still requires energy What happens during exercise? • Exercising tissues require an increase in blood flow • Cardiac output (Q) must increase • Cardiac output = heart rate (HR) x stroke volume (SV) Q = HR x SV But how does that affect blood pressure? MAP = Q x TPR Mean Arterial Pressure (MAP) Cardiac Output (Q) Total Peripheral Resistance (TPR) MAP = Diastolic +1/3 (systolic-diastolic) Effects of Exercise on Blood Pressure • Dynamic Exercise – – – – Need increased Q Increased HR Decreased TPR Diastolic BP stays ~ the same – Systolic BP increases and then levels off or slightly decreases • Static Exercise – – – – – Need increased Q Increased HR Increased TPR Increased MAP Increased DBP/SBP