Knowra Excretion Excretion Excretion is the removal of metabolic waste products and other unwanted substances from an organism’s body. It helps regulate the internal chemical environment.
Kidney : An organ that filters blood, regulates fluid and electrolyte balance, and produces urine. Kidneys remove urea and other wastes from blood while controlling water and salt levels.
Metabolism : The chemical reactions that build, break down, and transform substances in living organisms. Excretion removes by-products generated as cells obtain energy and build molecules.
Ammonotelism : Excretion of nitrogen mainly as ammonia, usually requiring abundant water for dilution. This strategy removes nitrogen cheaply but depends on access to water.
Urine : A liquid waste produced by the kidneys, containing water, urea, ions, and other dissolved substances. Its composition reflects kidney waste removal and regulation of body fluids.
Nephron : The kidney’s microscopic functional unit, where blood filtration and selective reabsorption produce urine. Its filtration and reabsorption steps determine which substances leave the body in urine.
Nitrogenous waste : Waste compounds containing nitrogen, produced chiefly by the breakdown of proteins and nucleic acids. Its toxicity and water cost shape how animals excrete nitrogen.
Ureotelism : Excretion of nitrogen mainly as urea, which is less toxic than ammonia and needs less water. It trades the energy cost of making urea for lower water loss.
Dialysis : A treatment that removes wastes and excess fluid from blood when kidney function is inadequate. It can partly replace the kidneys’ waste-removal role in kidney failure.
Urea cycle : A series of liver reactions that converts toxic ammonia into urea for excretion. It makes nitrogenous waste safer to transport from the liver to the kidneys.
Ammonia : A highly toxic nitrogen-containing compound formed during amino acid breakdown. Its toxicity requires rapid removal or conversion into less harmful compounds.
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