Liver.

 

Liver:

• Largest gland in the body.

• Located on the right side below the lungs in the upper abdominal cavity.

• Superficially it is covered by a peritoneum which separates it into lobes.

• Has two main lobes – right and left lobe.

• Right lobe is further divided into caudate, and quadrate lobe.

• The hepatic blood vessels enter the liver at the porta hepatis.

• The gallbladder rests in a recess on the inferior surface of the right lobe.

• The structural and functional unit of the liver is “Lobule”.

• Each liver lobule is hexagonal in shape.

• Composed of hepatocyte (liver cell) plates radiating outward from a central vein,

• Portal triads are found at each of the six corners of each liver lobule.

• Liver sinusoids – enlarged, leaky capillaries located between hepatic plates

• Kupffer cells – hepatic macrophages found in liver sinusoids.

• Functions of Hepatocytes:

1. Production of bile

2. Processing bloodborne nutrients

3. Storage of fat-soluble vitamins

4. Detoxification.

• Secreted bile flows between hepatocytes toward the bile ducts in the portal triad and is stored in Gallbladder.

• Composition of Bile:

• A yellow-green, alkaline solution containing bile salts, bile pigments, cholesterol, neutral fats, phospholipids, and electrolytes.

• Bile salts are cholesterol derivatives that:

• Emulsify fat

• Facilitate fat and cholesterol absorption

• Help solubilize cholesterol

• Enterohepatic circulation recycles bile salts

• The chief bile pigment is bilirubin, a waste product of heme.

Functions of the Liver:

1. Metabolism:

1. Carbohydrate Metabolism: 

1. Stores Glycogen.

2. Gluconeogenesis.

3. Glycogenolysis.

2. Fat Metabolism:

1. Oxidation of fatty acids. (Liver utilizes energy through fat metabolism).

2. Synthesis of Lipoproteins.

3. Synthesis of phospholipids and cholesterol.

4. Converts large amounts of carbohydrates and proteins into fats.

3. Protein Metabolism:

1. Parenchymal cells of the liver synthesize plasma proteins.

2. Deamination of amino acids.

3. Urea cycle to remove ammonia from the body.

2) Secretion of bile.

3) Storage of many vitamins like fat soluble vitamins and cyanocobalamin.

4) Breakdown of RBCs and defense against microbes by Kuffer cells.

5) Production of heat.

6) Detoxification of drugs and bacterial toxins.

Commonly Asked Questions.

1. Explain the structure and functions of the liver.