41.4 Nitrogenous Wastes

41.4 Nitrogenous Wastes

  • uric acid diffuses into the tubules.
    • Exchange pumps in the tubules transport H+ ion into the cell and K+ or Na+ ion out of the water.
    • The osmotic pressure which draws water, electrolytes, and nitrogenous waste into the tubules is altered by the secretion of ion.
    • When organisms are faced with low-water environments, water and electrolytes are reabsorbed and uric acid is excreted as a thick paste or powder.
  • It is important for organisms to conserve water by not dissolving waste in water.
  • The arthropods remove nitrogenous waste and other solutes from the hemolymph.
    • The Na+ and K+ ion are transported into the tubules.
    • The water enters the tubules through a process called osmosis.
    • There, the hemolymph gets some nutrition back into it.
    • Water follows the Na+ and/or K+ ion pumped into the hemolymph.
    • The waste is flushed down the toilet.
  • A close-up look at the Malpighian tubules is included in this.
  • Nitrogen is one of the major macromolecules in biological systems.
    • During the breakdown of nitrogen-based macromolecules, carbon, hydrogen, and oxygen are taken out and stored in the form of carbohydrates and fats.
    • The body excretes excess nitrogen.
    • The formation of ammonia requires large quantities of water and energy in order to get out of a biological system.
    • Animals that live in water tend to release ammonia.
  • Terrestrial organisms excrete nitrogenous waste.
    • The animals have to convert ammonia into urea or uric acid.
    • Urine and uric acid are produced by mammals, including humans.
  • There is urea in the urine.
    • 2 NH3 (ammonia) + CO2 + 3 ATP + H2O - H2N CO-NH2 is the chemical reaction that converts ammonia to urea.
  • The L-ornithine is converted into different intermediates before being regenerated at the end of the urea cycle.
    • The ornithine cycle is also referred to as the urea cycle.
    • Toxic levels of ammonia in the body can be caused by the deficiency of the ornithine transcarbamylase.
    • The first two reactions are in the mitochondria and the last two are in the cytosol.
  • Ammonia is converted to urea in the urea cycle.
  • The theory of evolution suggests that life began in the water.
    • The urea cycle is one of the pathways that evolved to adapt to a changing environment.
    • The evolution of the uric acid pathway is thought to have been caused by a lack of water.