Helminths Flashcards
Define parasitology
The branch of science concerned with the study of parasitic organisms
Define protozoa
A phylum of the kingdom Protista
Define helminth
A parasitic worm: the adult form is often visible to the naked eye but the eggs are microscopic and are the infectious/diagnostic form
Define dioecious
Having the male and female reproductive organs in separate individuals
Define monoecious
Having both the male and female reproductive organs in the same individual
Define arthropod
An invertebrate animal of the phylum Arthropoda (insects, arachnids, and crustaceans). Have segmented bodies, hard external skeletons, and jointed legs.
Define scolex
The head of the worm
Define proglottid
An individual hermaphroditic reproductive segment which, when they mature, fall off the tail of the cestode and dissolve, and the eggs inside are released.
Define strobila
The entire body of a cestode
Define ectoparasite
A parasite that lives on the outside of its host (e.g. fleas)
List the distinguishing characteristics of helminths
Large multicellular organisms usually visible to the naked eye in the adult stage. Can have elongated, flat, or round bodies.
List the distinguishing characteristics of nematodes.
Nematodes aka roundworms are round and non-segmented. Have complete digestive systems and are dioecious.
List the distinguishing characteristics of cestodes
Cestodes are tapeworms, which are a type of flat worms, and are flat and segmented. They’re monoecious and typically found in the digestive system.
List the distinguishing characteristics of trematodes
Trematodes are flukes, and are flat and non-segmented. They absorb food through a cuticle.
Describe a parasitic infection in which humans serve as a definitive host
A cestode called Taenia solium (pork tapeworm); the infective stage is the eggs, and the larvae hatch in the intestine and bore into the intestinal wall. They can produce tissue cysts called cysticerci.