Objective 6: 3 classes of Helminthes (+ Examples)

Question 1

Helminths 101: the Basics

Answer 1

• PARASITIC WORMS, highly differentiated multicelular organisms
• complex life cycles
• most are dependent on an intermediary host or vector for ASEXUAL REPRODUCTION
• disease is often caused by host inflammatory responses (Ex: Schistosomiasis) and in proportion to the number of infecting organism

Question 2

Roundworms (nematodes)

Answer 2

-collagenous tegument and non-segmented structure (hookworms & Trichinella)

• larvae penetrate skin (often through bare feet)–>venous circulation–>heart&lungs–>respiratory tract–>mouth..swallowed–>small intestine (ADULT worm). CYle takes ~1 week
• Image: Hookworms attached to intestinal mucosa

Question 3

Flatworms (Cestodes)

Answer 3

• gutless worms, heads sprout a ribbon of flat segments (tapeworms)
• Insert pic

Question 4

Flukes (trematodes)

Answer 4

• primitive leaflike worms with syncytial integument (schistosomes)
• Image: 4 Schistosoma mansoni trematodes