BIO 101 Lecture Notes - Lecture 21: Sap, Gastrulation, Mesoderm
8 Apr 2016
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11/16/15 bio101 lecture notes: evolution of a fluid-filled body cavity. Coelomates-bilaterians that posses a coelom that is completely lined in mesoderm. Acoelomates are bilaterians that subsequently lost their coelom, no enclosed body cavity. Provides a space/container for the circulation of oxygen and nutrients. Enables the internal organs to move and grow independently of each other. When the muscles on one side contract, the fluid-filled chamber changes shape and the animal bends: variation of the events of early embryonic development. Gastrulation-formation of the gut and the embryonic tissue (germ) layers. Circle of cells, pore become mouth or pore becomes anus. Protostomes (mouth first)-as cells start to move inside and form the gut, a pore is created and that pore is one side of the gi tracts, which becomes the mouth. Deuterostomes (second mouth) (anus first)-the pore becomes the anus first. Protostomes: block of solid mesoderm splits to form coelom. Deuterostomes: mesoderm pockets pinch off of gut to form coelom.
