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44 Cards in this Set
- Front
- Back
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Where do Adult tapeworms live?
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In the intestines of members of all classes of vertebrates.
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The body of an adult tapeworm typically consists of the following body structures:
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Scolex
Neck Strobila |
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Describe the scolex of tapeworms of medical importance.
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At anterior region
Suckers (usually 4) Hooks (1 or more in circles) |
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What is a rostellum?
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Some speices have a protrusibe, dome shaped region at the apex of the scolex where hooks are located.
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What are bothria?
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Long grooves on some speices instead of suckers. Usually 2 but can be up to 6.
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Describe the neck of a tapeworm.
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Long or short between scolex and strobila. proglottids are formed at the posterior end by transverse constrictions.
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What happens if there is no neck present in the tapeworm?
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Porglottids are formed at the posterior end of the scolex.
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What are Proglottids?
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Segment-like structures. They are not true segments. As new ones are produced older ones move further away from the anterior end and gradually increase in size.
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What is a whole series of proglottids of a tapeworm referred to as?
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strobila
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What are the 3 categories of proglottids?
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Immature, mature and gravid.
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Describe immature proglottids:
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male & female reproductive organs have not developed or in the process of developing but are not functional.
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Describe mature proglottids:
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Primary reproductive organs (testes and ovaries) are developed. Cross-fertilization may occur between mature proglottid of the same tapeworm or adjacent tapeworms of the same speices. Some can fertilize themselves.
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Describe gravid proglottids:
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Most reproductive organs have degenrated. Typically contain a greatly enlarged uterus that is packed with eggs.
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Describe the eggs of the proglottids:
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the eggs are not ova. most contain a fully developed larva, but some contain a developing embryo.
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How are gravid proglottids shed?
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Terminal gravid proglottids detach daily & pass intact out of the DH with the feces.
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What is other methods of gravid proglottids exiting the DH?
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Crawl out the anus.
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List 2 ways that eggs can be released from the gravid proglottid before the proglottid detaches.
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Disintegrate (tears or slits) eggs are released into intestine. some speices have a uterine pore or tears/slits while still attached detaches when it is senile or exhausted of eggs.
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desribe the skin of tapeworms.
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Nonciliated syncytial tegument with microtiches.
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Function of the skin of tapeworms.
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Absorb nutrients - since the tapeworms lack a digestive system.
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What are microtriches?
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Tiny projections on the outer surface of the syncytial tegument that increase the surface area for nutrient absorption. They can only be seen by electron microscope.
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Describe the reproduction process for tapeworms.
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Most speices are monoecious. Each mature proglottid contains 1 complete set of both male & female reproductive systems.
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List the possbile male reproductive parts of tapeworms:
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Seminal vesicle, ejaculatory duct, cirrus, male genital pore.
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List the possible female reproductive parts of tapeworms:
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Ovary, oviduct, seminal receptacle(spermatheca), vagina, vitelline gland, vitelline ducts, ootype, uterus, female genital pore.
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Describe the genital atrium of tapeworms.
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sunken chamber that has a male & female genital pore.
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Describe the vagina of tapeworms.
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Channel sperm pass through to seminal receptacle.
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Some speices of tapeworms lack a vagina. Describe fertization for those worms.
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Hypodermic impregnation occurs in which the cirrus is forced through the body wall and sperm deposited in the parenchyma. It is not known how the sperm get to the seminal recptacle.
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describe the ootype of tapeworms.
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the ootype is an area of the oviduct and is not a separate organ as in flukes.
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describe the disappearing uterus of some tapeworms.
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The eggs either singly or in groups are enclosed in egg capsules that are embedded within the parenchyma.
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Tapeworm Life Cycle in general:
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All are parasites. Typically have an indirect LC with 2 or more hosts. DH is a vetebrate, IH vertebrate or invertebrate. some species have more than 1 IH.
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There are 3 types of larva that may present within eggs. 2 are of medical significants what are they?
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1. Oncospheres or hexacanths.
2. Coracida |
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Define Oncospheres or hexacanths
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They are spherical in shape and have 6 hooks. They typically hatch out of eggs after the eggs are eaten.
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Define Coracidia. (coracidium)
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They have 6 hooks. Eggs that contain them hatch in H20. These larvae are ciliated and are free-swimming.
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What are the typical stages of a speices life cycle that has a coracidium stage?
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Adult, egg, coracidium, oncosphere, procercoid, plerocercoid, adult.
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What is a procercoid?
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Oncosphere metamorphos into it and it has hooks at it posterior end and a scolex.
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What is a cercomer?
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A sturcture located at the posterior end of a procercoid that has hooks.
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What are the typical stages of a speices life cycle that has a oncosphere stage?
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Adult, egg, oncosphere, cysticercoid.
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Define Oncosheres.
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It is fully developed when the egg passes out of the DH, but only will hatch after being eaten by an IH.
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Define a cysticercoid.
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It is solid-bodied and it's scolex is invaginagted into it's body. Part of its body is encysted, but the cercomer is outside the cyst wall.
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Define a cysticercus.
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Sphereical to oval in shape. It has a fluid-filled bladder. The scolex is introverted (inside out) in addition to be invaginated.
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What is a coenurus?
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Sphereical to oval in shape. When a cyst has budding of a multiple # of scolices occurs from the germivative membrane.
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Define Protoscolices.
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Multiple number of scolices.
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What is a unilocular hydatid?
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Sphereical to oval in shape. When budding of a multiple # of protoscolices and endogenous budding of brood capsules occurs. Each has numberous protoscolices inside it. They can grow very large holding quarts of fluid.
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What is multilocular or alveolar hydatids?
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Exogenous budding has occurred resulting in a single mass with many armlike process.
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What happens if exogenous budding occurs in an abnormal host?
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Protoscolices are not produced. Budding forms numerous daughter cyst as separation of the side arms occurs.
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