6 Feb 2018

Lymphatic system anatomy

Immune System is a defence system that protects against diseases, White blood cells (WBC) or Leukocytes that destroy the disease-causing organisms (Virus, Bacteria, and parasites)


WBC (White blood cells / Leukocytes)  


        1.   Neutrophils


        2.   Lymphocytes


        3.   Monocytes


        4.   Eosinophils


  5.   Basophils



The Lymphatic System is part of the circulatory system and immune system.


Comprising a network of lymphatic vessels that carry a clear fluid called lymph towards the heart from the tissues.


One of the main functions of the lymph system are to provide an accessory return route to the blood (Extracellular fluid).


           The blood first exit the microvascular exchange blood vessels to become interstitial fluid.


           Lymph is the fluid that is formed when interstitial fluid enters the lymphatic vessels of the lymphatic system.


           The lymph is then moved along the lymphatic vessel network by either intrinsic contractions of the lymphatic passages or by extrinsic compression of the lymphatic vessels via external tissue forces (e.g., the contractions of skeletal muscles).


           Eventually, the lymph vessels empty into the lymphatic ducts, which drain into subclavian veins, near their junction with the internal jugular veins.



The lymphatic system consists of


            A)  Lymphatic organs,


            B)  Lymphatic vessels,


            C)  Lymph.





           The primary or central lymphoid organs (Thymus and Bone marrow) generate lymphocytes (T cells and B cells).


            The secondary or peripheral lymphoid organs (Lymph node and spleen).



THYMUS GLAND: is located in the mediastinum of the thoracic cavity anterior and superior to the heart and posterior to the sternum.


The Thymus receive immature T cells that are produced in the red bone marrow and train them into functional, mature T cells that attack only foreign cells (bacteria, viruses, and fungi)


The thymus is the largest and most active during the neonatal and pre-adolescent periods. After puberty, it will be converted into adipose tissue. But the “T” cells remains in body throughout the life.



BONE MARROW, Consist of stem cells.


          Redbone marrow


          Yellow bone marrow



Red marrow is found mainly in the


        A.  Flat bones - sternum, skull, ribs, vertebrae and shoulder blades.


        B.  Long bones (Epiphyseal ends) - Femur, tibia, and humerus.


        C.  Produces WBC, Platelets and RBC



Yellow marrow is found in the hollow interior of the diaphyseal portion of the shaft of long bones. Produces fat. By the time a person reaches old age, nearly all of the red marrow is replaced by yellow marrow.


SPLEEN: Organ located in the left upper quadrant next to the stomach, it removes old red blood cells and holds a reserve of blood. The spleen contains many tiny blood vessels and hollow sinuses that store blood. Release its stored blood into circulation to replace blood lost during a traumatic injury.


Many platelets are also stored with the blood in the spleen to help form blood clots to prevent further blood loss. Spleen produces White blood cells and removing microbes.


A LYMPH NODE OR LYMPH GLAND: is an ovoid or kidney-shaped organ, acting as filters for foreign particles and cancer cells, Lymph nodes are major sites of B and T cells, and other white blood cells.


LYMPH is very similar to blood plasma: it contains lymphocytes. It also contains waste products and cellular debris together with bacteria and proteins.

Associated organs composed of lymphoid tissue are the sites of lymphocyte production.


Peyer's patches are small masses of lymphatic tissue found throughout the ileum region of the small intestine. They monitoring intestinal bacteria populations and preventing the growth of pathogenic bacteria in the intestines.



TONSILS: Cluster of lymphatic tissue present in nose, mouth and pharynx.



Three groups of tonsils,


  1.  Pharyngeal tonsils (Adenoids)


  2.  Palatine tonsils


  3.  Lingual tonsils



Provide protection against harmful pathogens that may enter the body through nose / mouth.




1. AIDS - Acquired immunodeficiency syndrome

2. HIV - Human immunodeficiency virus

3. HPV - Human papillomavirus

4. IPV - Inactivated poliovirus vaccine

5. NSAID - Nonsteroidal anti-inflammatory drug

6. MMR - measles-mumps-rubella (vaccine)

7. MRSA - Methicillin-resistant Staphylococcus aureus

8. PUO - Pyrexia of unknown origin

9. TD - Tetanus-diphtheria



Test your knowledge:

        A. Anatomy Quiz