ch 13 - excretion and homeostasis Flashcards
excretion
the removal of the waste products of metabolism and substances in excess of requirements
urea
a waste product produced in the liver, from the breakdown of excess amino acids, removed from blood by kidneys
urine
solution of urea and other waste materials in water, produced by kidneys
ureter
one of a pair of tubes, that carries urine from the kidneys to bladder
urethra
tube that carries urine from bladder to outside
deamination
the removal of the nitrogen containing part of amino acids to form urea
nephron
one of the thousands of microscopic tubes inside a kidney, where urnine is made
glomeruli
network of blood capillaries, where blood is filtered in a kidney
reabsorption
in a kidney nephron, taking back required substances into the blood
how is urea produced?
Protein is taken to the alimentary canal (stomach, duodenum, ileum) and digestive enzymes break down the protein to amino acids during digestion. The amino acids are absorbed into the blood capillaries in the villi of the ileum, and its taken to the liver by the HEPATIC PORTAL VEIN. Needed amino acids are turned into protein or released into the blood to be assimilated by body cells. The amino acids that aren’t needed are deaminated (nitrogen part of amino acid removed) The urea is then dissolved in the blood plasma and taken to kidneys for excretion.
how is urine formed?
Blood flows into kidney through renal artery, then into the glomerulus, where blood is filtered. The filtrate contains water, urea, glucose, ions. The filtrate moves into the nephron. Reabsorption then takes place (taking in useful substances back into the blood, easily absorbed due to the capillaries being so close to the nephron) The final liquid that flows out of the nephron is urine (urea, salts, water).
