Lymphatic System

Topics: Immune system, Lymphatic system, Antibody Pages: 23 (6951 words) Published: April 16, 2014
The Lymphatic System
And Immunity
 
The cells, tissues, and organs of the lymphatic system play a central role in the body’s defenses against a variety of pathogens, or disease-causing organisms.  Acts against environment hazards, various pathogens, and internal threats. Lymphocytes (primary cell) are vital to or overcoming infection and disease. Lymphocytes respond to invading pathogens, abnormal body cells, and foreign proteins. They act to eliminate these threats or render them harmless through a combination of physical and chemical attacks. Immunity is the ability to resist disease and infection.

There are two forms of immunity that work independently or together. -       Innate (nonspecific) immunity
-       Adaptive (specific) immunity
The body has several anatomical barriers and defense mechanisms that either prevent or slow the entry of infectious organisms, or attack them if they do enter. These mechanisms are called innate (nonspecific) defenses because they do not distinguish one threat from another. These are defenses present at birth. Lymphocytes provide an adaptive (specific) defense known as an immune response. Lymphocytes respond specifically, if a bacterial pathogen invades peripheral tissues lymphocytes organize a defense against that particular bacterium. Developed over time. All the cells and tissues involved in producing immunity are considered part of the immune system. This physiological system not only includes the lymphatic system but also parts of the integumentary, cardiovascular, respiratory, digestive, and other systems.  

The Lymphatic System
 
Components
Lymph – Originates as interstitial fluid. Resembles plasma but contains less suspended proteins. Lymphatic Vessels or Lymphatics - Begin as lymphatic capillaries in the peripheral tissue, connect to form into larger lymphatics (with valves) and then into lymphatic ducts. Lymphatic Ducts - Collect the lymph and returns it into circulation. Lymphoid Tissues – Connective tissues dominated by lymphocytes. Peyer’s patches, vermiform appendix, tonsils, lymph nodules. Lymphoid Organs – Lymph nodes, thymus and spleen

Lymphocytes, a small number of other phagocytes, and other cells.  
Function
To gather interstitial fluid and bring it to the nearest lymphatic organ or tissue for cleansing by lymphocytes and other WBC’s. The cleansed fluid is then returned to the circulatory system via the right lymphatic duct or thoracic duct. To produce, maintain, and distribute lymphocytes that provide defense against infections and other environmental hazards.  Lymphoid tissue and lymphoid organs produce and store most of the body’s lymphocytes. Areas of the red bone marrow also produce lymphocytes, along with other defense cells such as monocytes and macrophages. To provide an effective defense, lymphocytes must detect problems, and they must be able to reach the site of injury or infection. Lymphocytes, macrophages, and microphages circulate within the blood. They are able to enter or leave the capillaries that supply most of the body. Capillaries normally deliver more fluid to peripheral tissues than they carry away, the excess fluid returns to the blood stream through the lymphatic system. This continuous circulation of extracellular fluid helps transports lymphocytes and other defense cells from one organ to another. Also helps to maintain blood volume, and eliminate local variations in the composition of interstitial fluid.

Components of the Lymphatic System
 
Lymphatic Capillaries
All lymphatic vessel carry lymph from peripheral tissues to the venous system. The smallest lymphatic vessels are called lymphatic capillaries. The lymphatic network begins with lymphatic capillaries, or terminal lymphatics, which branch through peripheral tissues. Lined by endothelial cells with an incomplete or absent basement membrane. The endothelial cells are not tightly bound; they overlap, acting as a one-way valve. Permits fluid and solutes (including...
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