Count to 10 - Anaesthetic Primary Podcast EP25 – Regional Circulation | Anaesthetic Primary Topic | Cardiac Physiology | CT10
Aug 28, 2024
Dive into the fascinating world of regional circulation and discover how systemic circulation and the physics of blood flow influence blood pressure. Explore the differences between arterial, capillary, and venous systems, along with the principles of Ohm's law and its applications to blood flow. Uncover the complexities of microcirculation and the role of baroreceptors in blood pressure regulation. Learn about the cardiovascular control arc and how various factors, including sympathetic tone and hormones, modulate vascular resistance.
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Functional Differences Of Vessel Systems
- Systemic circulation divides into arterial, capillary and venous systems with distinct roles and wall structures.
- Arteries convert pulsatile LV output into continuous flow while capillaries maximize exchange and veins act as high-capacitance reservoirs.
Radius Rules Resistance
- Flow equals pressure difference divided by resistance (Ohm's law) and Poiseuille's law links resistance to viscosity, length and radius^4.
- Radius dominates resistance because it is raised to the fourth power, so small diameter changes massively alter flow.
Why Poiseuille Still Applies Clinically
- Poiseuille's law assumptions (steady, laminar, Newtonian) don't strictly hold for blood, but physiology compensates via Windkessel, arteriolar smoothing and apparent viscosity.
- These mechanisms justify using the equation clinically despite blood's non-ideal behavior.