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Physical principles of hemodynamic and bioreology. The Heart and the Cardiovascular System. (2) Cardiac Mechanics. (1) Cardiac electrophysiology.
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The Heart and the Cardiovascular System (2) Cardiac Mechanics.(1) Cardiac electrophysiology.
The Heart: two pumps in series: (1) Pulmonary circulation: propels blood through lungs for exchange of O2 and CO2. (2) Systemic circulation: propels blood to all other tissues or organs of body.
Types of flow Flow of fluid in a cylindrical tube may be laminar of turbulent. Laminar flow: flow in lamina, fluid particles do not move in radial or circumferential direction. In Laminar flow the pressure drop (DP) is proportional to flow.
Poiseuille’s law Effect of stenosis degree on resistance
Types of flow Turbulent flow: irregular flow of fluid elements. Rapid radial and circumferential mixing. In turbulent flow the pressure drop is approximately proportional to square of flow.
Pressure and Volume in the Circulation Pressure is pulsatile in the arteries but steady in the capillaries and veins. Pressure falls along the circuit with the greatest fall across arterioles. Volume is greatest in the venous system. At any time most of the blood is in veins
The Cardiac Cycle Ventricular Ejection Phase Atrial Systole Ventricular Filling Isovolumetric Contraction Isovolumetric Relaxation 120 Semi-Lunar Valve Closes Semi-Lunar Valve Opens 100 Arterial Pressure 80 60 Pressure (mm Hg) 40 AV Valve Closes AV Valve Opens 10 Ventricular Pressure 0 R Electrocardiogram T P S Q Atrial Systole Ventricular Systole Diastole Approx. Time 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 Arterial Pressure Curve
Relationship of myocardial resting sarcomer length (end-diastolic volume) to developed force (peak systolic ventricular pressure) during ventricular contraction in the intact dog heart
ESV Pressure-volume loop C D B A
DV C = DP DVa DPa = Ca Compliance: Definition: In regards to aortic mechanics DVor Dva is stroke volume (SV) and DPor DPa is pulse pressure (PP, or Ps-Pd). For aorta
120 Systolic mm Hg Dicrotic Notch 100 Pulse Pressure Mean Pressure 80 Diastolic Systole Diastole Aortic Pressure Waveform