Biology 2601A/B Lecture Notes - Osculum, Choanocyte, Cardiac Output
25 Nov 2012
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Document Summary
Circulation is a pressure-driven bulk flow of fluid that transports: o2, co2, nutrients, organic wastes, hormones, agents of the immune system, heat, and hydraulic pressure for organ function. The notion that most primitive animal phyla lack circulatory systems is inherently flawed because circulatory systems do not necessarily need to involve blood as the vascular fluid. Cardiac output is about 5l/min, a huge amount of work performed by the heart. Sponges belong to the phylum perifora and have dominated the world"s oceans from 600 mya to the present day. A sponge is essentially a pump, which, at approximately every 5 seconds, will pump the volume of its body size through its system. Sponges accomplish this because they possess massive cardiac tissue. Incoming water comes through the entire body of the animal and then shoots out through the top of the animal because it helps deliver oxygen and nutrients to the system as well as helps with feeding.
