Fatty acids and their metabolic products are also used for the synthesis of
cholesterol, lecithin, lipoproteins, and other complex lipids.
- Vitamin and Iron Storage
Vitamins A, B, and D and several of the B-complex vitamins are stored in large
amounts in the liver.
Iron and copper, are also stored in the liver.
Because the liver is rich in these substances, liver extracts have been used for
therapy for a wide range of nutritional disorders.
- Drug Metabolism
The liver metabolizes many medications
Metabolism generally results in loss of activity of the medication, although in
some cases activation of the medication may occur.
One of the important pathways for medication metabolism involves conjugation
(binding) of the medication with a variety of compounds, such as glucuronic or
acetic acid, to form more soluble substances.
The conjugated products may be excreted in the feces or urine, similar to
bilirubin excretion.
- Bile Formation
Bile is continuously formed by the hepatocytes and collected in the canaliculi
and bile ducts.
It is composed mainly of water and electrolytes such as sodium, potassium,
calcium, chloride, and bicarbonate, and significant amounts of lecithin, fatty
acids, cholesterol, bilirubin, and bile salts.
Bile is collected and stored in the gallbladder and is emptied into the intestine
when needed for digestion.
Bile also serves as an aid to digestion through the emulsification of fats by bile
salts.
Bile salts are synthesized by the hepatocytes from cholesterol. After conjugation
or binding with amino acids, they are excreted into the bile.
The bile salts, together with cholesterol and lecithin, are required for
emulsification of fats in the intestine, which is necessary for efficient digestion
and absorption.
