BIOL 2030 Lecture Notes - Lecture 8: Flatworm, Biliary Tract, Nerve Plexus
Document Summary
3 types of nervous tissue organization: subepidermal nerve plexus. Simplest system, resembling the diffuse cnidarian nerve net: sub epidermal nerve plexus+longitudinal nerve cords. 1-5 nerve cord pairs lying under the musculature: nerve cords + a primitive brain. Nerve cords (1-3 pairs), with connecting nerves (ring commissures) forming a ladder-type pattern. Considered more sophisticated because you have a greater concentration of nerve tissue forming a sort of nervous system versus just a mesh. Cysticercosis: cysts in brain, spinal cord and other organs (if human ingests cysticercus) If oncosphere is ingested, it makes a cyst but its a dead end unless . Other common examples: fish tapeworm-diphyllobothrium datum. De nitive hosts: humans, cats, dogs, bears: can reach lengths between 1-18m, dog tapeworm-echinococcus granulosus. Infestation can occur in virtually any organ system (ex. liver ukes, blood ukes, lung ukes, urinary tract. Egg usually released in faeces, must reach water.
