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Helminthes

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الكلية كلية الصيدلة     القسم  فرع البايولوجي     المرحلة 2
أستاذ المادة رشا هادي صالح عبد العيساوي       10/03/2018 14:15:26
Helminthes
Trematodes

General characteristics
- Fluke is the common name for any member of the class Trematoda - Trematodes are relatively simple, flatworms, soft-bodied, the fluke body is unsegmented and covered by a tough cuticular tegument for its protection from digestive enzymes of the host. - Possess two suckers, one oral anterior in position and surrounding the mouth and the other the ventral lying on the ventral surface. - They have a blind digestive system, i.e. without anus: the only opening is the mouth. waste products are regurgitated. - Most are hermaphroditic and capable of self-fertilization. except for schistosoma, which have separate male and female. - Have complicated life cycle occurring in two or more host, involving sexual reproduction in mammalian and other vertebrate (definitive hosts) and asexual reproduction in snail (intermediate hosts). Each species requires a certain species of snail as an intermediate host. - Trematode eggs usually have a smooth, transparent, yellow-brown shell and may have spines - Reproductive system: Uterus is the largest organ; a single ovary, testes and a series of glandular structures that produce egg. Uterus may be filled with thousands of eggs. - Trematodes infect various organs of the human host (for example, intestinal veins, urinary bladder, liver, or lung).
Types of Flukes
Flukes can be categorized into groups on the basis of the systems they infect:
(1) The hermaphroditic liver flukes which reside in the liver such as Clonorchis sinensis, Fasciola hepatica
(2) The hermaphroditic intestinal fluke occur attached to the mucosa of the intestine such as Fasciolopsis buski, Heterophyes.
(3) The hermaphroditic lung fluke which reside in the lung such as Paragonimus
(4) The bisexual blood flukes such as Schistosoma, inhabits the blood in some stages of their life cycle which live in the intestinal or vesical (urinary bladder) venules


Blood flukes: Schistosoma
Schistosoma is by far the most important trematode parasite. It is flat worms live in the blood stream of warm-blooded hosts and undermine the health of the blood. They differ from other trematodes in that they have separate sexes. Adults exist as two sexes but are attached to each other. The female resides in a groove in the male, the gynecophoric canal (schist) where he continuously fertilizes her eggs The male worms resemble a rolled leaf where they bear the longer and more slender female in a ventral canal (the gynaecophoric canal). Both sexes have two suckers, one anterior and one ventral, which are used to grip venule walls. They require definitive and intermediate hosts to complete their life cycle. Humans are definitive hosts, while snails are intermediate hosts. Dogs, cats, rodents, pigs, horses, and goats are reservoirs for S. japonicum.
Schistosoma is the only trematode that invades through the skin; all other trematodes infect only via ingestion. It s causes schistosomiasis or Bilharzia disease and is the most important of helminth diseases. The source of infection is through swimming in infected water. There are three main species of schistosoma that infect humans, have similar life cycles:

1- S. mansoni: Adult worms live in the plexus of veins draining the rectum and colon, and in branches of the portal vein in the liver. Its cause intestinal disease.
2- S. japonicum: Adults worms live in the anterior mesenteric blood vessels and in the portal vein in the liver. Its cause intestinal disease.
3- S. haematobium: Adult worms lives in the veins draining the urinary bladder Its causes urinary tract disease.



Schistosoma (blood flukes)


المادة المعروضة اعلاه هي مدخل الى المحاضرة المرفوعة بواسطة استاذ(ة) المادة . وقد تبدو لك غير متكاملة . حيث يضع استاذ المادة في بعض الاحيان فقط الجزء الاول من المحاضرة من اجل الاطلاع على ما ستقوم بتحميله لاحقا . في نظام التعليم الالكتروني نوفر هذه الخدمة لكي نبقيك على اطلاع حول محتوى الملف الذي ستقوم بتحميله .
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