Parasitology Lecture - Phylum Platyhelminthes' General Characteristics

Flatworms does not only include the parasitic flukes (trematodes) and tapeworms (cestodes) but also other?

free-living flatworms

What do you call a flukes and tapeworms?

trematodes, cestodes

They are bilaterally what? and compressed where? and has a definite what?

symmetrical, dorsoventrally, anteroposterior axis

All classes of flatworms possess a bilaterally similar related systems, what are these systems? which terminates in?

excretory system, collecting tubules, capillaries; flame cells

What do flatworms lack?

circulatory system

Their sexual organs are highly?

elaborated, complicated

In most species, the sexes are combined in a single organism, called? while in some group, sexes are found in separate organisms, called?

hermaphrodite, monoecious; diecious

The life cycle may involve a single? an example tapeworm from the first statement is the? The life cycle may also require two or more? similar to some trematodes like?

obligatory host, Hymenolepis nana; consecutive hosts, Paragonimus westermani

There are 2 classes of utmost importance under Phylum Platyhelminthes, which are?

class cestoda, class trematoda

Cestodes inhabit the what of vertebrates? while the larva parasitizes the what of vertebrates and invertebrates

intestinal tract, tissues

Adult cestodes usually look like? They vary in sizes from a few?

ribbons, tapelike segmented parasites; millimeter to several meters

Cestode body consists of 3 distinct regions, what are these regions?

head or scolex, neck, strobili or body

What features does the head, neck, and body of cestodes offer?

holdfast organs, region of growth, series of segments or proglottids

Each segments or proglottid has a complete unit, what are these units? said unit have also organs, what are these organs?

reproductive units; male, female sex organs

The 3 life cycle of cestodes include the?

egg stage, larval stage, adult stage

What are cestode eggs called due to their description?

hexacanth embryo of oncosphere

What are different names of cestode's larval stage?

cysticercus, cysticercoid larva, coracidium, procercoid, plerocercoid larva

All cestodes require an? and in some species the direct host can serve as an?

intermediate host, intermediate host

Trematodes have a complicated life cycle involving what?

alternation of generations and hosts

What are usually the primary hosts of trematodes?

snails

Most flukes which parasitizes man are also? and their non-human vertebrate hosts serve as?

animal parasites, reservoirs for human infections

Trematodes affect various areas of the body, what are these areas?

Circulatory system, Intestines, Liver, Lungs

What parasites affects the following? Circulatory system, Intestines, Liver, Lungs

blood flukes, Echinostoma ilocanum, Fasciola hepatica, Paragonimus westermani

What are the varying sizes of length does trematode have?

1 mm to several cm

Trematodes have organs for attachment, they are called? and there are two of them called?

suckers; oral, ventral suckers

Trematode alimentary canal is present but are? and because of the fact in the first statement, the anus is?

incomplete, absent

the trematode esophagus do what in front of the ventral sucker? into a pair of? which maybe simple or branched or may reunite to form a?

bifurcates, blind intestinal caeca, single caecum

trematode reproductive system is highly? and complete in each?

developed, individual

Trematodes lay eggs so they are? and the eggs are? which develop in? and schistosomes eggs aren't?

oviparous, operculated, water, operculated

The 3 life cycle of trematodes include the?

egg stage, larval stage, adult stage

What are different names of trematode's larval stage?

miracidium, sporocyst, redia, cercaria, metacercaria

What is the general definitive host of trematodes? which means they harbors the?

human, adult worm

What is usually the intermediate host of trematodes? which means they harbor what stage? but sometimes a secondary intermediate host (fish, crab or another snail) is required for?

freshwater snail, mollusk; larval stage, encystment

What do you call a host in which a parasite reaches the adult or sexually mature stage?

definitive host

A host in which the infectious agent in question undergoes the adult and asexual stage of its reproduction

definitive host

Definitive hosts are also called a?

final host

What is a host in which a parasite passes one or more of its asexual stages?

intermediate host

Usually designated first and second, if there is more than one

intermediate host

what host in which larval or developmental stages occur

intermediate host