BIO202H5 Lecture Notes - Lecture 5: Malpighian Tubule System, Gastrointestinal Tract, Hemolymph
Document Summary
Lecture 5: balancing water part 2 (1) terrestrial arthropods. Malpighian tubules in hindgut where hemolymph passes through. Malpighian tubules slender tubes found in posterior regions of alimentary canals that absorb water, solutes and wastes from hemolymph. Wastes released as uric acid or urea. No initial filtration but active transport into tubule of ions filtration occurs in bowman"s capsule ions, solutes and water transferred to hemolymph. Water reabsorbed into hemolymph using atp powered pump to build concentration gradient inside wall of hindgut taking in water at same time to dilute so there is higher c of water since in dehydrating environment. Water follows by osmosis challenge to keep water. Urate also transported acidifies lumen and precipitates as crystalline uric acid. Osmolarity gradient also maximized by countercurrent flow. The pre-urine (pre-filtrate it has water and solutes) is moving from the descending segment into the medulla and then going up towards the distal tubule and the collecting duct.
