Cestodes Introduction Flashcards
In what phylum are tapeworms classified?
platyhelminthes (flatworms)
In what 2 orders are human tapeworms found?
- cyclophyllidea 2. pseudophyllidea
What is the scolex?
chief neural ganglia w physical and chemical sensory endings
What cestodes have an acetabulate scolex?
(4 muscular cups) cyclophyllidea
What tapeworms have a bothraite scolex?
( shallow grooves) pseudophyllidea
Where is the neck?
immediately posterior to scolex
What is strobilation?
formation of proglottids
What does PZQ do to cestodes?
damages tegument of neck
The strobila is made up of
proglottids.
What is inside the gravid?
egg
What is a rostellum scolex?
muscular, armed -> has hooks, unarmed -> no hooks
Are tapeworms monoecious or dioecious?
monoecious
Why is the cestode tegument described as a syncytium?
has no cell boundaries
Which is the outermost layer of the tegument?
glycocalyx
What is the microtrix?
increase SA & maintain position in the glycocalyx
What is the function of the function of the distal cytoplasm?
no nuclei. vesicles maintain glycocalyx
What is found between the distal cytoplasm & proximal cytoplasm?
tegumental muscle (longitudinal & circular)
How are the distal cytoplasm and proximal cytoplasm connected
cytoplasmic connective (channels)
How do cestodes acquire nutrients?
no digestive tract -> all nutrients absorbed
Give an example of diffusion across the tegument?
proxidine (vit B6) - high to low [] in worm no E required
How is glucose taken up by the tegument?
active transport (low to high gradient so requires E)
What are intrinsic enzymes?
produced by worm & embedded in tegument part of contact digestion
What is contact digestion? Give an example.
digest molecules in host gut. small molecules taken up by active transport. ex: amylase (starch -> glucose)
What is protandry?
male 1st sperm stored
How does the uterine structure differ in Cyclophyllideans & Pseudophyllideans?
cyclo: end blindly vs. pseudo: ends in uterine pore
What are apolysis and anapolysis? In which order does each occur?
apolysis - gravid proglottid breaks off & disperses eggs in cyclo vs. anapolysis - uterine pore in pseudo
How do the vitelline glands differ in the two orders?
cyclo: single, compact vs. pseudo: scattered
What is an oncosphere?
larva
Why is the called a hexacanth embryo?
has 6 hooks
How many hosts do most cestodes need to complete their life cycle?
2
What stage develops inside the egg?
onchosphere
Where does the egg hatch?
IH or outside of IH and larva gets eaten by IH
What happens once the larva gets inside the intermediate host?
migrates to parenteral site & develops to metacestode (juvenile)
In which host is the metacestode found?
DH
What stimulates the development of the metacestode to the adult?
digest enzymes
What are the treatments for most cestode infections?
niclosamide & PZQ
