BIOL 1010 Lecture Notes - Lecture 27: Extracellular Fluid, Reabsorption
14 May 2017
School
Department
Course
Professor
Document Summary
Produced in the vertebrate liver by a metabolic cycle that combines ammonia and carbon dioxide. Is about 100,000 times less toxic than ammonia. Held in the body in a concentrated form, but needs water for disposal. Land animals (insects, land snails, many reptiles, including birds) avoid the water loss problem almost completely. Largely insoluble in water (water cannot be used to dilute it) Excreted as a semisolid paste (the white material in bird droppings is mostly uric acid hence the reason it can cause so much damage to paint jobs on cars) Animals must expend more energy to excrete uric acid than to excrete urea, but the higher energy cost is balanced by the great savings in body water. Reproduction type can influence whether an animal will excrete uric acid or urea. Urea can diffuse out of a shell-less amphibian egg or be carried away fro(cid:373) a (cid:373)a(cid:373)(cid:373)alia(cid:374) e(cid:373)bryo i(cid:374) the (cid:373)other"s blood.
