Physiology of lymph node

Lymphatic system

An accessory route by which blood and interstitial space can exchange fluid. Lymph from the lower part of the body empties into the thoracic duct together with the upper left part of the head, neck and chest regions. The right upper part of the body is drained by the right lymph duct. The right lymph duct and the thoracic duct both enter the venous system of the body. Lymphatic system is a specialized way of fighting and localizing infections.

Almost 100 ml per hour of lymph passes through the thoracic duct of a resting man  each hour. Also about 20 ml passes through the circulation every hour which then totals 120 ml/hr or 2-3 l per 24 hours. Interstitial fluid pressure has effect on the lymph flow in the body. The following factors influence interstitial fluid pressure

  • Decreased plasma collioid osmotic pressure

  • Increased capillary permeability

  • Elevated capillary pressure

  • Increased interstitial fluid colloid osmotic pressure

Lymph flow does not rise further when the interstitial fluid pressure rises above 1 to 2 ml higher than atmospheric pressure.

Function- Histophysiology of lymph node

Clusters of differentiation

When monoclonal antibodies are raised against lymphocytes, three major divisions are recognised called clusters of differentiation. They are

  • CD3+

  • CD4+

  • CD8+

All lymphocytes seem to be positive for CD3+ but two classes of CD4+ and CD8+ emerge amongst T lymphocytes. They give rise to

  • Natural killer cell

  • Suppressor enhancer cell

  • Suppressor effector cell

  • Cytotoxic suppressor cell

  • Helper/inducer cell

Suppressor cells help to suppress the production of antibodies by lymphocytes

Helper cells help to enhance the production of antibodies by lymphocytes.

Cytotoxic cells directly kill cells in their vicinity.


     


Cross section on of lymph node x40

 

 

 

 

 

 

 

 

 

 

 

 

 

Introduction
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Lymphatic drainage
Organ integration
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