Blood Pressure

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  • Topic Anchor: Blood Pressure 
    • Pressure experienced by blood inside the circulation
      • Fluid travels from high → low pressure, which drives circulation and perfusion
      • Highest pressure in aorta, lowest in veins
    • Blood pressure usually reported as pressure inside arteries
      • Systolic (SBP)
        • highest pressure in vessels
        • during contraction (systole) of ventricles
      • Diastolic (DBP)
        • lowest pressure in vessels
        • during relaxation (diastole) and filling of ventricles
      • Mean arterial pressure (MAP)
        • Average blood pressure throughout a cardiac cycle
        • Calculated as MAP = (SBP + 2*DBP)/3
    • Blood pressure depends on two factors
      • Blood pressure = cardiac output * vascular resistance
      • Cardiac output (CO)
        • Determines the amount of blood pumped into the circulation by the heart per unit time.
        • Calculated as CO = stroke volume x heart rate
      • Vascular Resistance (VR)
        • Resistance to blood flow determined by diameter of blood vessels
        • Controlled by vasoconstriction/dilation
        • Largest pressure drop across arterioles
          • Main source and determinant of vascular resistance
    • Regulation of blood pressure
      • Nervous Control acts quickly/fast
        • Baroreceptors in arteries detect changes in blood pressure, then signal brainstem to alter sympathetic and parasympathetic nervous system
      • Hormones act slowly