BIOL 204 Lecture Notes - Lecture 15: Nemertea, Urethra, Peritubular Capillaries
Document Summary
I. water-salt balance and osmoregulation: hyperosmotic: higher solute concentrations; lower free h2o concentration. 2: osmoconformer: animal is isosmotic with the environment. 6: active transport to counteract diffusion requires energy. 2: 5% of bmr of many fishes. 4: 30% of smr of brine shrimp (inhabiting hypersaline lakes) 8: big osmotic problem for most terrestrial animals. 2: waxy cuticles prevent water loss in most ecdysozoa. 4: shells of many terrestrial gastropods. 6: dead keratinized skin cells of vertebrates. 8: nocturnal activity reduced water loss by evaporation. 10: best counteraction is by drinking and eating. Dehydration of animal: transport epithelia: layers of epithelial cells specialized for moving solutes in specific directions. Animals that excrete ammonia need access to large amounts of water in order to dilute its toxicity. Urea: made in the liver by combining ammonia and carbon dioxide. Excreted by animals who do not have access to large amounts of water. Takes a lot of energy to produce.
