05. Trematodes Flashcards
What are trematodes commonly referred to as?
flukes
What is the taxonomy of D. caninum? (recall from last lecture)
Order Cyclophillydea
Family Dipylidiidae
Genus Dipylidium
Species caninum
What is the common name of D. caninum? (recall from last lecture)
Dog/cat tapeworm
All tapeworms are ____-parasites
endoparasites
are trematodes only found in the intestine?
NO - they can inhabit many organs
What organ system do Schistosoma spp. infect?
vasculature of the gastro-intestinal or genitourinary systems
What organ system do Fasciolopsis, Heterphyes heterophyes, and related organisms infect?
They are intestinal flukes, they infect the GI tract
What organ system do Clonorchis sinensis, Fasciola hepatica and Opisthorcis infect?
The liver
What organ system do Paragonimus westermany and related species infect?
They are lung flukes, they infect the lungs and other organs such as the CNS
Why is the life cycle of a digenetic trematode complex?
It involves at least 2 hosts
What kind of animal is the first intermediate host of the digenetic trematode?
A mollusc (usually a snail)
What kind of animal is the DH of the digenetic trematode?
A vertebrate
Do you always have a redia?
NO
Do you always have a sporocyst?
YES
What are characteristic of the adult digenetic trematode?
the two suckers
What are the names and functions of the two suckers in a digenetic trematode?
Oral sucker - for attachment and feeding (mostly feeding)
acetabulum (ventral sucker) - for attachment only, there is no internal opening
What type of muscle is found on the suckers?
smooth muscle - found in bands on the suckers for strong attachment
What kind of body wall do digenetic trematodes have?
tegument
what are the two layers of tegument
syntegument and cytotegument
Describe the syntegument (outer layer)
- it contains mitochondria, secretory bodies and occasional spines
- it is a chemical layer that lies on top of outer cell membrane
Describe the cytotegument (inner layer)
- consists of cell bodies beneath the tegument
- each cell contains a nucleus and organelles (such as the rER and golgi)
- separated from syntegument by layers of tegumental muscle
- connected to syntegument by cytoplasmic bridges
what are the functions of the cytotegument?
- involved in the production of mucus
What are the functions of the tegument? (3)
1- osmoregulation and excretion
2- synthesis and secretion of mucus (to protect against host enzymes)
3- Absorption of nutrients for trematode nutrition
What is the morphology of the adult trematode digestive tract?
- muscular scmooth muscle creates sucking action
- short esophagus leads to 2 long, blind-ending cecum
- no anus
- proteins are digested in the lumen of the intestine and absorbed through the intestinal epithelium