BIO 2135 Lecture Notes - Lecture 8: Nephridium, Trematode Life Cycle Stages, Cell Membrane
Document Summary
Platyhelminthes: an acoelomate triploblastl midterm cutoff coelem fluid can be a cavity for nitrogenous wastes to buikld up in fluid, then can filter. But this group no coelum, different excretory structure excretory system: diffusion across body surface. Protonephridia: water balance, metabolic waste to a certain extent. Filtering, tuft of cilia inside flame cell, push water down tube, very thin membrance at junction between flame cell and tube cell get negative pressure from beating, creating suction which draws fluid in! Flame cell sits between cells, bathed in interstitial fluid. Large components will not get in, or leave main cells, like food. But smalls tuff and nitrogenous wastes will diffuse. Membrane surface pulling across it water and anything small enough to be dissolved in via action of cilia. Little pores on side of animal allow water and nitrog wates to exit animal why flame cell?in more transparent ones, see what looks like a little flickering flame, the beating cilia.
