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Introduction to the cardiovascular system
Published on October 31, 2019 35 min
A selection of talks on Physiology & Anatomy
Hello, I'm Jeremy Ward. I was Head of Physiology at King's College London for 10 years and I researched into the cardiovascular system and respiratory system. I'm going to be giving an "Introduction to the Cardiovascular System".
The areas I'm going to talk about. What is the cardiovascular system? Why is it important? The basic organization, structure and function of the heart and vasculature, and important questions yet to be answered. By convention, blood pressure is still usually measured in millimeters of mercury or Torr not SI units kilopascals. So I will be following this convention throughout this lecture.
So what is the cardiovascular system? It consists of the heart and the vasculature as one might expect. The heart pumps oxygenated blood through the arteries, so it can be distributed to the tissue metabolism. Note, that arteries always go from the heart, veins go to the heart. The veins collect deoxygenated blood from the tissues and return it to the heart and lungs for re-oxygenation. A parallel series of vessels( lymphatics) collects excess fluid from the tissues and returns it to the circulation.
So why is the cardiovascular system important? It evolved due to the limits of diffusion. Diffusion is fairly slow and very distance dependent. So whilst simple diffusion is sufficient for metabolism in single celled organisms, it becomes far too slow as distances approach a millimeter or more. Small multicellular organisms circumvent this with thin walls, tubular structures such as the gut seen in the hydra at the bottom. This eventually evolved into the cardiovascular system as we know it. So larger organisms use circulatory system which bring the blood close enough to individual cells for diffusion to be sufficiently rapid to support metabolism. Cardiovascular system was therefore developed very early in evolution and is pretty similar in design across multicellular organisms. Particularly from fish all the way up to humans.