HUBS1404 Lecture Notes - Lecture 1: Pulmonary Circulation, Circulatory System, Closed System
19 Jul 2018
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Functions: oxygen and nutrients to cells - primary, co2 and waste from cells - primary, transport hormones, antibodies and immune cells - secondary. Why have a cv system: cells require oxygen and nutrients from the environment, they also produce carbon dioxide ad metabolic wastes, as organisms become larger they require more sophisticated systems to keep internal cells. For small organisms surrounded by water, simple diffusion is sufficient alive. Nutrient uptake and waste removal relies primarily on diffusion gradients: cells can only afford to be a short distance from oxygen and nutrients. Also they need to dispose of their wastes down significant concentration gradients: multicellular organisms with no circulatory system are limited in size because of concentration gradients. Moving fluid past cells helps maintain concentration gradients when animals become larger. Distribution of blood volume: circulation holds around 5l in the average individual, at rest the bulk of the blood is found in the systemic veins and venules.
