01:146:328 Lecture Notes - Lecture 14: Praziquantel, Mitosis, Cecum
3 Apr 2016
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Document Summary
The phylum platyhelminthes includes various dorsoventrally flattened animals known as flatworms, who are typically bilaterally symmetrical and lack a body cavity. If present, the digestive tract is incomplete therefor the only opening to the exterior, the mouth, seven both for ingestion and egestion. They usually lack skeletal, circulatory, and respiratory systems. The space between the body wall and internal organs contain connective tissues fibers, muscle, and unattached and fixed cells of various types. The fibers, cells, and spaces between are referred to as the parenchyma. 4 classes make up the phylum but only. Trematoda and cercomeromorphae contain flatworms parasitic to humans. An evolutionary scheme for trematodes propose that they arose from a stock of free- living flatworms, became intimately associated with molluscs, and developed into parasitic forms. Evolutionary divergence of this endoparasite gave rise to digenea and aspidobothrea. Digenea proliferated asexually in molluscs and parasitized evoking vertebrates, while aspidogastrean forms remained within their molluscan host through adulthood.
