Browsing by Author "OUDJANE , Faiza"

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    ANIMAL PHYSIOLOGY 2nd year Agronomy : The invertebrates & the vertebrates
    (Faculty of Sciences, 2023) OUDJANE , Faiza
    The first Metazoans developed an external rather than an internal circulation system. the sponges and the Cnidarians don't have neither heart, neither system circulatory differentiated. the Transport of O2 and nutrients takes place from cell to cell by diffusion. It's the middle exterior which serves as a transport medium thanks to a permanent renewal ensured by the activity of ciliated, flagellated or muscular cells. In all other cases, transport is assured by internal fluid movements : blood or hemolymph