The lymphatic system is a widely distributed system with multiple functions. Its role in circulation is to return excess fluid and proteins from the tissues to the bloodstream. The fluid carried in the lymphatic system is called lymph. Lymph drains from the lower part of the body and the upper left side into the thoracic duct, which travels upward through the chest and empties into the left subclavian vein near the heart. The right lymphatic duct drains the upper right side of the body and empties into the right subclavian vein. Another function of the lymphatic system is to absorb digested fats from the small intestine. These fats are then added to the blood near the heart. One other major function of the lymphatic system is to protect the body from impurities and invading microorganisms. Along the path of the lymphatic vessels are small masses of lymphoid tissue.
Other organs and tissues of the lymphatic system include the tonsils, located in the throat, the thymus gland in the chest, and the spleen in the upper left region of the abdomen.
The Lymphoid Organs : Lymphoid organs form part of the body’s immune system. Lymphoid organs defend the body against invading pathogens that cause infections or spread of tumors. These organs exist as primary, secondary or tertiary, based on the stage of lymphocyte development and maturation the organ is involved in.
► PRIMRY LYMPHOID ORGANS:
The primary lymphoid organs serve to generate lymphocytes from immature progenitor cells. Progenitor cells possess the capacity to differentiate into a specific cell type. Progenitor cells divide for a limited number of times,
► PRIMRY LYMPHOID ORGANS:
The primary lymphoid organs serve to generate lymphocytes from immature progenitor cells. Progenitor cells possess the capacity to differentiate into a specific cell type. Progenitor cells divide for a limited number of times,
depending on the need of the body. Immunologists occasionally refer to these organs as “central lymphoid organs.” Examples of primary lymphoid organs include the bone marrow and the thymus.
► SECONDARY LYMPHOID ORGANS:
Secondary lymphoid organs take charge of maintaining mature but naive lymphocytes. These organs initiate adaptive immune response. Immunologists refer to these organs as “peripheral lymphoid organs.” Peripheral lymphoid organs serve as the site for lymphocyte activation. Antigen-presenting cells present antigens in these organs and this will lead to expansion and affinity maturation of the lymphocytes. Mature lymphocytes circulate in the blood and the peripheral lymphoid organs until they encounter the specific antigen. Examples of secondary or peripheral lymphoid organs include adenoids, the tonsils, lymph nodes, Peyer’s patches, the spleen, and even the skin, among others. All of these form the mucosa-associated lymphoid tissues.
► TERTIARY LYMPHOID ORGANS:
The tertiary lymphoid tissue usually contains less number of lymphocytes. It plays an important role during inflammation. Inflammation forms part of the vascular response to unfavorable stimuli. Stimuli include pathogens, damaged cells or other irritants. Inflammation protects the body by removing harmful stimuli and initiating a healing process.
► SECONDARY LYMPHOID ORGANS:
Secondary lymphoid organs take charge of maintaining mature but naive lymphocytes. These organs initiate adaptive immune response. Immunologists refer to these organs as “peripheral lymphoid organs.” Peripheral lymphoid organs serve as the site for lymphocyte activation. Antigen-presenting cells present antigens in these organs and this will lead to expansion and affinity maturation of the lymphocytes. Mature lymphocytes circulate in the blood and the peripheral lymphoid organs until they encounter the specific antigen. Examples of secondary or peripheral lymphoid organs include adenoids, the tonsils, lymph nodes, Peyer’s patches, the spleen, and even the skin, among others. All of these form the mucosa-associated lymphoid tissues.
► TERTIARY LYMPHOID ORGANS:
The tertiary lymphoid tissue usually contains less number of lymphocytes. It plays an important role during inflammation. Inflammation forms part of the vascular response to unfavorable stimuli. Stimuli include pathogens, damaged cells or other irritants. Inflammation protects the body by removing harmful stimuli and initiating a healing process.
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