What do mammals excrete

While aquatic animals can easily excrete ammonia into their watery surroundings, terrestrial animals have evolved special mechanisms to eliminate the toxic ammonia from their systems.

Urea is the major byproduct of ammonia metabolism in vertebrate animals. Uric acid is the major byproduct of ammonia metabolism in birds, terrestrial arthropods, and reptiles. Skip to content Chapter Osmotic Regulation and Excretion. Learning Objectives By the end of this section, you will be able to: Compare and contrast the way in which aquatic animals and terrestrial animals can eliminate toxic ammonia from their systems Compare the major byproduct of ammonia metabolism in vertebrate animals to that of birds, insects, and reptiles.

Excretion of Nitrogenous Waste The theory of evolution proposes that life started in an aquatic environment. Gout Mammals use uric acid crystals as an antioxidant in their cells. Figure Compare and contrast the formation of urea and uric acid. Answers A C It is believed that the urea cycle evolved to adapt to a changing environment when terrestrial life forms evolved.

The urea cycle is the primary mechanism by which mammals convert ammonia to urea. The urea cycle utilizes five intermediate steps, catalyzed by five different enzymes, to convert ammonia to urea. Birds, reptiles, and insects, on the other hand, convert toxic ammonia to uric acid instead of urea. Conversion of ammonia to uric acid requires more energy and is much more complex than conversion of ammonia to urea.

Glossary ammonia compound made of one nitrogen atom and three hydrogen atoms ammonotelic describes an animal that excretes ammonia as the primary waste material antioxidant agent that prevents cell destruction by reactive oxygen species blood urea nitrogen BUN estimate of urea in the blood and an indicator of kidney function urea cycle pathway by which ammonia is converted to urea ureotelic describes animals that secrete urea as the primary nitrogenous waste material uric acid byproduct of ammonia metabolism in birds, insects, and reptiles.

Previous: Remember there is one type of waste product that is not excreted from the body - poo! That's right, although it is a part of the body's waste, it is not a bi-product of your metabolism like urine is - it is expelled from the body, not excreted!

Find out more about Excretion Excretion cleans up after respiration. Search the Learning Zone. These amino acids are transferred back to the host. In reptiles and ureotelic fish not all of these steps have been experimentally confirmed. Reptiles like birds, reflux urine into the intestine where it is exposed to the microflora. However, the capacity of these microbes to breakdown the uric acid and urea and utilize ammonia for amino acid synthesis has not been documented.