Excretion

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  • Created by: emews
  • Created on: 02-11-17 17:26
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  • Excretion
    • Excretion is the removal of:
      • Toxic materials
      • Waste products of metabolism
      • excess substances from organisms
    • Excretion is not the same as egestion
    • Plants
      • Plants need to excrete excess carbon dioxide and oxygen
      • Oxygen is a waste product of photosynthesis
    • Human excretory organs
      • sweat glands in the skin produce sweat. The water in sweat cools body down
      • Excess carbon dioxide and some water vapour are exhaled
      • The kidneys are organs of the urinary system
    • urinary system
      • blood is brought to the kidney in the renal artery. The kidneys filter the blood and then reabsorb useful materials such as glucose.
      • Urine is taken from the kidneys to the bladder by the ureters.
      • urine contains water, urea and salts
      • Urea is produced in the liver when excess amino acids are broken down.
    • the kidney
      • The inner part of the kidney is called the medulla and the outer part is the cortex
      • blood is filtered at high pressure to remove glucose, water, salts and urea
    • The nephron
      • Urine is produced in microscopic structures in the kidney called nephrons.
      • The blood is put under high pressure
      • ultrafiltration of the blood happens, in which water, ions, glucose and other small molecules pass into the tubule.
      • collecting duct is responsible for:
        • the selective reabsorption of water
        • Sending urine to the ureter
    • ADH
      • The water content of the blood is controlled by a hormone called ADH.
      • Different amounts of ADH are realeased into the bloodstream according to the concentration of the blood plasma.
      • The diagrams show what happens when there is either too little or too much water in the blood.

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