1.Regulation of glucose level

The liver maintains the blood glucose level at approximately 90mg glucose per 100cm3 blood. The liver prevents blood glucose levels from varying up and down according to how recently food has been eaten.

glucose-regulation

  • In response to high blood sugar levels, secretion of insulin hormone by the pancrease is increased. Insulin stimulates the conversion of glucose to glycogen in the liver. (but more is stored in muscle. 100g of glycogen are stored in liver)
  • In response to low blood sugar levels, secretion of glucagon hormone by the pancrease is increased. Glucagon stimulates the breakdown of glycogen to glucose in the liver.
  • In times of stress or cold this activity is also stimulated by adrenaline and noradrenaline.

2.Regulation of lipid content

The liver is involved in the processing and transport of fats rather than their storage.

lipid regulation

  • The liver converts excess carbohydrates (especially glucose)to fat.
  • Removes cholesterol from the blood and breaking it down.
  • When necessary, the liver synthesizes the cholesterol.
  • If glucose is in short supply, the liver can break down fats into fatty acids and glycerol for respiration.

3.Protein metabolism

  • Deamination: the amino group of the excess amino acids taken up into diet is removed from the amino acid and used to make ammonia.
  • Urea formation: ammonia is toxic so it is converted to a harmless product, Urea.
  • Transamination: non essential amino acids which are deficient in the diet is produced. Eg: Glycine, Alanine, Cysteine, Glutamic acid
  • Plasma protein production: these are components of plasma and the majority of them are synthesized from amino acid in the liver. Eg: Albumin, Globulin 

4.Detoxification 

  • The toxic ammonia, which is formed in deamination is converted to a harmless product, Urea.
  • The liver removes harmful substances taken into the body such as alcohol and nicotine.
  • Bacteria and the pathogens are removed from the blood in the sinusoids by Kupffer cells.
  • kupffer cells in liver
     

5.Heat production

  •  When the body temperature falls down, the metabolic activities of the liver is increased and the respiratory substances are broken down to produce heat energy. Hence the body temperature increases and reaches the normal temperature.
  • In response to high body temperature, the metabolic activities fall down to reduce the heat production.

6.Elimination of hormones

  • the liver destroys almost all the hormones to various extents
  • eg: testosterone, aldosterone- rapidly destroyed
  • less rapidly destroyed: insulin, glucagon, gut hormones, female sex hormones, adrenal hormones, ADH, thyroxin.

7.Elimination of haemoglobin

  • When the Red Blood Cells are broken down, the haemoglobin they contain is released and taken up in the liver by the Kupffer cells, and broken down into Haem and Globin.
  • Globin is the protein part of the molecules.
  • The iron from the Haem is removed and the remaining part of the molecules forms a green pigment called Biliverdin.
  • This is converted to Bilirubin, which is yellow and a component of bile

8.Storing blood

  • Approximately 300ml – 1500ml of blood is stored in the hepatic portal vein of the liver.
  • liver storing blood

9.Storing vitamins

  • The main vitamins stored in the liver are the fat soluble vitamins A D E and K.
  • The liver also stores some of the water soluble vitamins, namely Vit-B and C.
  • Especially those of the B group such as nicotinic acid, B12 and folic acid.

10.Storing minerals

  • Those elements required in small amounts such as copper, zinc, cobalt and molybdenum (trace elements) are stored in the liver along with iron and potassium.

Functions of the liver which are not a part of homeostasis

  • Production of bile
  • Resisting infections by producing immune factors and removing bacteria from the bloodstream

 

A sample mind map to make you feel easy....

functions of the liver

 

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