LIVER EXCRETION

Biology

LIVER EXCRETION

Role of Liver in Excretion

  • The liver lies below the diaphragm and it receives blood from hepatic artery and hepatic portal vein.
  • Blood flows out of the liver through hepatic vein.
  • Excretion of Nitrogenous Wastes
  • Excess amino acids cannot be stored in the body; they are deaminated in the liver.
  • Hydrogen is added to amino group to form ammonia which combines with carbon (IV) oxide to form urea.
  • The urea is carried in the blood stream to the kidneys.
  • The remaining carboxyl group, after removal of amino group, is either oxidized to provide energy in respiration, or built up into carbohydrate reserve and stored as glycogen or converted into fat and stored.

Breakdown and Elimination of Haemoglobin

  • Haemoglobin is released from dead or old red blood cells which are broken down in the liver and spleen.
  • Haemoglobin is broken down in the liver and a green pigment biliverdin results which is converted to yellow bilirubin.
  • This is taken to the gall bladder and eliminated as bile.
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Elimination of Sex Hormones

  • Once they have completed their functions, sex hormones are chemically altered by the liver and then taken to the kidney for excretion.

Common Liver Diseases

Cirrhosis

  • Cirrhosis is a condition in which liver cells degenerate and are replaced by scar tissue .
  • This causes the liver to shrink, harden, become fibrous and fail to carry out its functions. Causes
  • Chronic alcohol abuse, schistosomiasis infection, obstruction of gall-bladder.

Symptoms

  • Headache, nausea, vomiting of blood and lack of appetite, weight loss, indigestion and jaundice.

Control and Treatment

  • Avoid alcohol consumption and fatty diet.
  • Use drugs to kill the schistosomes if that is the cause.

See also

FACTORS AFFECTING RATE OF BREATHING IN HUMANS

GASEOUS EXCHANGE IN A MAMMAL – HUMAN

GASEOUS EXCHANGE IN AN AMPHIBIAN – FROG

GASEOUS EXCHANGE IN INSECTS

GASEOUS EXCHANGE IN ANIMALS

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