Intrinsic Regulation of the Heart: Starling’s Law Increased Venous Return Increased cardiac muscle stretch Increase contraction force Increased SV = Increased CO Occurs without SNS/PSNS involvement Exercise….
Pressure and Resistance Increased Resistance = Increased Pressure Increased Resistance = Increased Work of the Heart Measurement: 120/80 mm Hg
Vasoconstriction: Decreases Vessel Diameter Increases Resistance Increases Diastolic BP Increases Work of Heart Increases SBP later SNS, Cold, Hemorrhage etc cause vasoconstriction to “rescue” vital organs
Vasodilation: Increases Vessel Diameter Decreases Resistance Decreases Diastolic Pressure PSNS, Heat, Local Exercise Demand cause vasodilation to perfuse skin, muscles for special situations
Systolic and Diastolic BP: Systolic: Ventricular Systole Greatest Arterial Pressure Reflects CO and heart’s contribution to BP Diastolic: Ventricular Diastole Lowest Arterial Pressure Reflects the resistance of the vessels to CO
Essay Choices: Exercise and the Heart/Vessels Chronic Hypoxic Vasoconstriction of the Pulmonary Arteries The effect of Nitroglycerin on peripheral resistance, work of the heart, BP