MEDICAL BIOLOGY, ANATOMY, HUMAN PHYSIOLOGY AND PATHOLOGY - Ya.I. Fedoniuk 2010

BIOLOGY

CHAPTER 2. BIOGEOCENOTIC LEVEL OF LIFE ORGANIZATION AND HUMAN PLACE IN IT

2.4. MEDICAL HELMINTHOLOGY

Phylum Flatworms (Plathelminthes)

The phylum Flatworms encompasses about 7,300 species. In the course of evolution, flatworms originated from Coelenterates and, in turn, gave rise to Roundworms and Annelids. Animals of this phylum are characterized by: 1) triploblastic Structure (development of ecto-, ento-, and mesoderm in embryos); 2) presence of a Skin-muscular sac (body integument fused with Muscles); 3) absence of a body cavity (the space between Organs is filled with parenchyma); 4) bilateral body Symmetry; 5) dorsoventrally flattened body shape; 6) presence of well-developed Organ Systems: muscular, digestive, excretory, nervous, and reproductive; 7) absence of circulatory and respiratory systems.

Of medical importance are parasitic flatworms of humans belonging to two classes: 1) Class Trematodes (Trematoda) and 2) class Tapeworms (Cestoidea).



Last update: 08/08/2026

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