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Reticuloendothelial system
 
 
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The reticuloendothelial system (RES), part of the immune system
Immune system

An immune system is a collection of biological processes within an organism that protects against disease by identifying and killing pathogens and tumour cells....
, consists of the phagocytic
Phagocytosis

File:Phagocytosis in three steps.pngPhagocytosis is the cell process of Phagocytes and Protists of engulfing solid particles by the cell membrane to form an internal phagosome, which is a food vacuole, or pteroid....
 cells located in reticular connective tissue
Reticular connective tissue

Reticular connective tissue is a type of connective tissue proper. It has a network of reticular fibers, made of type III collagen. Reticular fibers are not unique to reticular connective tissue, but only in this type are they dominant....
, primarily monocyte
Monocyte

Monocyte is a type of leukocyte, part of the human body's immune system. Monocytes have two main functions in the immune system: replenish resident macrophages and dendritic cells under normal states, and in response to inflammation signals, monocytes can move quickly to sites of infection in the tissues and divide/differentiate into mac...
s and macrophage
Macrophage

Macrophages are white blood cells within tissues, produced by the division of monocytes. Human macrophages are about 21 micrometres in diameter....
s. These cells accumulate in lymph node
Lymph node

A Lymph node is an organ consisting of many types of cells, and is a part of the lymphatic system. Lymph nodes are found all through the body, and act as filters or traps for foreign particles....
s and the spleen
Spleen

The spleen is an organ found in all vertebrate animals. In humans, the spleen is located in the abdomen of the body, where it functions in the destruction of redundant red blood cells, and holds a reservoir of blood....
. The Kupffer cell
Kupffer cell

Kupffer cells, also known as Browicz-Kupffer cells, are specialized macrophages located in the liver that form part of the reticuloendothelial system ....
s of the liver
Liver

The liver is a vital organ present in vertebrates and some other animals; it has a wide range of functions, a few of which are detoxification, protein synthesis, and production of biochemicals necessary for digestion....
 and tissue histiocyte
Histiocyte

A histiocyte is a Cell that is part of the mononuclear phagocytic system . The mononuclear phagocytic system is part of the organism's immune system....
s are also part of the RES.

Mononuclear phagocytic system and lymphoreticular system are synonymous with RES.

The reticuloendothelial system is divided into primary and secondary lymphoid organs.

rimary (or "central") lymphoid organs - the sites where the cells of the RES are produced.






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Encyclopedia


The reticuloendothelial system (RES), part of the immune system
Immune system

An immune system is a collection of biological processes within an organism that protects against disease by identifying and killing pathogens and tumour cells....
, consists of the phagocytic
Phagocytosis

File:Phagocytosis in three steps.pngPhagocytosis is the cell process of Phagocytes and Protists of engulfing solid particles by the cell membrane to form an internal phagosome, which is a food vacuole, or pteroid....
 cells located in reticular connective tissue
Reticular connective tissue

Reticular connective tissue is a type of connective tissue proper. It has a network of reticular fibers, made of type III collagen. Reticular fibers are not unique to reticular connective tissue, but only in this type are they dominant....
, primarily monocyte
Monocyte

Monocyte is a type of leukocyte, part of the human body's immune system. Monocytes have two main functions in the immune system: replenish resident macrophages and dendritic cells under normal states, and in response to inflammation signals, monocytes can move quickly to sites of infection in the tissues and divide/differentiate into mac...
s and macrophage
Macrophage

Macrophages are white blood cells within tissues, produced by the division of monocytes. Human macrophages are about 21 micrometres in diameter....
s. These cells accumulate in lymph node
Lymph node

A Lymph node is an organ consisting of many types of cells, and is a part of the lymphatic system. Lymph nodes are found all through the body, and act as filters or traps for foreign particles....
s and the spleen
Spleen

The spleen is an organ found in all vertebrate animals. In humans, the spleen is located in the abdomen of the body, where it functions in the destruction of redundant red blood cells, and holds a reservoir of blood....
. The Kupffer cell
Kupffer cell

Kupffer cells, also known as Browicz-Kupffer cells, are specialized macrophages located in the liver that form part of the reticuloendothelial system ....
s of the liver
Liver

The liver is a vital organ present in vertebrates and some other animals; it has a wide range of functions, a few of which are detoxification, protein synthesis, and production of biochemicals necessary for digestion....
 and tissue histiocyte
Histiocyte

A histiocyte is a Cell that is part of the mononuclear phagocytic system . The mononuclear phagocytic system is part of the organism's immune system....
s are also part of the RES.

Mononuclear phagocytic system and lymphoreticular system are synonymous with RES.

The reticuloendothelial system is divided into primary and secondary lymphoid organs.

Primary lymphoid organs

Primary (or "central") lymphoid organs - the sites where the cells of the RES are produced. The cells of the RES are produced in the bone marrow
Bone marrow

Bone marrow is the flexible biological tissue found in the hollow interior of bones. In adults, marrow in large bones produces new blood cells....
.

The thymus
Thymus

In human anatomy, the thymus is an organ located in the upper anterior portion of the Thoracic cavity just behind the sternum. The main function of the thymus is to provide an area for T lymphocyte maturation....
 is also included as it is the required site for T cell
T cell

T cells belong to a group of white blood cells known as lymphocytes, and play a central role in cell-mediated immunity. They can be distinguished from other lymphocyte types, such as B cells and natural killer cells by the presence of a special receptor on their cell surface called T cell receptors ....
 maturation.

Secondary lymphoid organs

Secondary (or "peripheral") lymphoid organs - the sites where the cells of the RES function. This includes the lymph nodes, tonsils, spleen, and "MALT" (mucosa-associated lymphoid tissue
Mucosa-associated lymphoid tissue

The mucosa-associated lymphoid tissue is the diffuse system of small concentrations of lymphoid tissue found in various sites of the body such as the gastrointestinal tract, thyroid, breast, lung, salivary glands, eye, and skin....
).

  • MALT is further divided into the "GALT" (gut-associated lymphoid tissue
    Gut-associated lymphoid tissue

    The digestive tract's immune system is often referred to as gut-associated lymphoid tissue and works to protect the body from invasion....
    ) and the "BALT" (bronchus-associated lymphoid tissue).


  • The Kupffer cells of the liver act as part of this system but are not organized into a tissue; rather, they are dispersed throughout the liver sinusoid
    Liver sinusoid

    A liver sinusoid is a type of Sinusoid that serve as a location for the oxygen-rich blood from the hepatic artery and the nutrient-rich blood from the portal vein....
    s.


  • The microglia
    Microglia

    Microglia are a type of glial cell that acts as the first and main form of active immune defense in the central nervous system . Microglia constitute 20% of the total glial cell population within the brain....
     of the Central Nervous System
    Central nervous system

    The central nervous system is the part of the nervous system that functions to coordinate the activity of all parts of the bodies of multicellular organisms....
     (CNS) can be considered a part of the reticuloendoethelial system. They are scavenger cells that proliferate in response to CNS injury.

Function

The secondary lymphoid structures function to survey all entering or circulating antigen and to mobilize an immune response against foreign antigen upon its discovery. The GALT and BALT are privy to a myriad of antigen entering the gastrointestinal and respiratory tracts, respectively. All extracellular fluid must filter through lymph nodes as it traverses the lymphatics on its way back to the systemic circulation. Antigen residing in the interstitium is thus swept to the lymph nodes for processing.

Finally, the spleen filters the blood in search of antigen. Upon the discovery of foreign antigen, all of these tissues react in a similar manner to amass an appropriate and multifaceted immune response.

Clinical significance


Lymphoma of the reticuloendothelial system is called reticuloendotheliosis
Reticuloendotheliosis

Reticuloendotheliosis is a lymphoma of the reticuloendothelial tissue..Types include:* Gaucher's disease* Histiocytosis* Mast-cell sarcoma...
.

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