Cestodes - tapeworms
Tape worm do not have - digestive system, their food is absorbed from the hosts intestine.
Cestodes Larval stages - parasitic in the tissues or body cavities of vertebrate or invertebrate hosts.
Neck + proglottids - = Strobila
In Diphyllobothrium scolex ...
Cestodes Questions with Correct
Answers Graded A+
Cestodes - ✔✔ tapeworms
Tape worm do not have - ✔✔ digestive system, their food is absorbed from the hosts intestine.
Cestodes Larval stages - ✔✔ parasitic in the tissues or body cavities of vertebrate
or invertebrate hosts.
Neck + proglottids - ✔✔ = Strobila
In Diphyllobothrium scolex is - ✔✔ spatulate & is provided with a long median ventral & a similar dorsal sucking groove or *bothrium*
In cestodes the tregion of growth &proliferation - ✔✔ Neck
cestodes alimentary canal - ✔✔ entirely absent
three types of segments of the strobila can be recognized: - ✔✔ 1. Immature: male and female organs are not differentiated.
2. Mature: male and female organs have become differentiated (male organs appear first).
3. Gravid: uteri are filled with eggs (other organs are atrophied or have disappeared).
Cestodes Covered - ✔✔ tegument containing microvilli (microtrichs).
Human tapeworm infections humans are the *definitive hosts*: - ✔✔ Taenia, Diphyllobothrium, Hymenolepis, and Dipylidium
Human tapeworm infections humans are *intermediate hosts*: - ✔✔ with larval-
stage parasites present in the tissues; diseases in this category include echinococcosis, sparganosis, taenia solium and coenurosis. Each mature segment contain: - ✔✔ 1. Excretory system: consists of paired ventrolateral and dorsolateral longitudinal canals, at frequent intervals are numerous tubules that originate from flame cells in the tissues.
2. Genital organs: full growth & function in the mature proglottids. In most species, there is one complete set of ♂& ♀organs.
According to egg ovi-position cestodes can be divided to two orders: - ✔✔ I. Order *Cyclophyllidea* Characteristics
II. Order *Pseudophyllidea* Characteristics
Order Cyclophyllidea Characteristics: - ✔✔ -Scolex is quadrate with four cup-
like round suckers. -No uterine opening for the exit of eggs from the gravid uterus
-Oncosphere is never a ciliated embryo.
Cyclophyllidea Adult Worms in the Intestine: - ✔✔ Taenia saginata
Taenia solium
Hymenolepis nana
Hymenolepis diminuta
Dipylidium caninum
Cyclophyllidea Larval Stages in Man: - ✔✔ -Hydatid cyst of Echinococcus granulosus and Echinococcus multilocularis -Cysticercus cellulosa of Taenia solium
-Coenurus cerebralis of Multiceps multiceps
-Coenurus glomeratus of Multiceps glomeratus
Order Pseudophyllidea Characteristics: - ✔✔ -Scolex "head" has two slit-like sucking grooves called bothria instead of suckers. -Eggs are operculated and can develop only in water; immature when oviposited (unembryonated) and oncosphere gives rise to ciliated embryo.
-Larval development proceeds in two intermediate hosts:
1- First larval stage is called *procercoid*. 2-Second larval stage is called *plerocercoid*.
Pseudophyllidea Adult worms in Intestine - ✔✔ Diphyllobothrium latum: Fish Tapeworm Pseudophyllidea Larval stages - ✔✔ Plerocercoid in Man:
Sparganum mansoni Sparganum proliferum
Which cestode in raw or rare beef containing cysticerci results in intestinal tapeworms? - ✔✔ Taenia saginata
Taenia saginata - ✔✔ beef tapeworm
Taenia saginata infection not found in - ✔✔ vegetarians and those who do not eat
beef
Taenia saginata adult worm lives in - ✔✔ *middle third of small intestine*
T. saginata can be up to - ✔✔ 4 to 6 meters long or sometimes up to 24 meters and 12 mm
broad.
T. saginata scolex - ✔✔ pear-shaped head (scolex) with four suckers and a single apical depression but no hooks.
T. saginata with ——— segments (proglottids) - ✔✔ 1000-2000
Taenia saginata Gravid proglottid number of branched lateral arms of the uterus - ✔✔ 15-20
A tapeworm larval cyst - ✔✔ Cysticercus bovis
T. saginata adult may live in the small intestine as long as - ✔✔ as 25 years and pass gravid proglottids with the feces.
Human infection result from - ✔✔ ingestion of uncooked or undercooked meat
Taenia saginata Pathogenesis & Symptoms - ✔✔ Light infections remain asymptomatic, but heavier infections may produce abdominal discomfort, epigastric pain, vomiting and diarrhea. -Deprivation of nutrition or loss of appetite.
-Allergic reactions. -Weakness.
-Weight loss.
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