THE RETICULOENDOTHILIEL SYSTEM

 THE RETICULOENDOTHILIEL SYSTEM

Reticulo endothelial system is an older terms for the mono-clear phagocyte system. Most endothelial cells are not macrophages here,

It is a network of connective tissue fibres inhabited by phagocytic cells such as macrophages ready to attack and ingest miabes,RES is a essential component of immune system.

General function of RES

• Phagocytosis: Bacterial ,dead cells or foreign particles.
• Immune function : processing antigen and antibodies production.
• Breakdown of aging RBC
• Storage and circulation of iron.

Components of RES

• Monocytes
• Macrophages located in skin ,liver , spleen,bone marrow,lymph-nodes , lungs.
• Endothelial cell , bone marrow , spleen , lymph nodes.

MACROPHAGES

Often remain fixed to their organs,they filter and destroy objects which are foreign to the body .such as bacteria viruses, some macrophages are mobile and they can group together to become one phagocytic cell in order to ingest largest foreign particles.

Types of macrophages.

• Kupffer cells in the liver 
• Microglia in the brain
• Reticular cell in the lymph-nodes , bone marrow and spleen
• Tissue histiocytes(fixed macrophages) in subcutaneous tissue 
• Alveolar cells in the lungs
• Osteoclast in bone

Function of macrophages

1. Begin by stem cell in bone marrow : mono-blast maturing to pre monocyte and mature monocyte release into blood
2. Stay for 10-20 hours in circulation
3. Then leave blood for tissue transforming into large cell macrophages.
4. Macrophages life spam is longer to few months in tissues.

TRANSFORMATION OF MONOCYTES TO MACROPHAGES

Characterised by an increase in:

• Cell size
• Number and complexity of intracellular organelles , Golgi, mitochondria and lysosomes.
• Intracellular digestive enzymes.

PHAGOCYTOSIS

• Phagocytosis is part of the natural and innate immune processes 
• Macrophages are a powerful phagocytic cells ,ingest upto 100 bacteria .ingest largest particles such as old RBC ,get rid of waste products.