Question

Explain the structure of the lymphatic system.

Answer 1

The lymphatic system consists of lymph, lymphatic capillaries, lymphatic vessels, lymph nodes and lymphatic organs.

1. Lymph:

1. It is the interstitial fluid (tissue fluid) present between the cells of a tissue.
2. It is colourless or yellowish fluid present in the lymph vessels.
3. It is composed of 94% water and 6% solids.
4. Lymph=Blood – [RBCs + Plasma proteins + platelets]

2. Lymphatic capillaries:

1. Small, thin walled vessels lined by endothelium resting on a basement membrane.
2. They are present throughout the body except spinal cord, brain, internal ear, bone marrow, eye ball.

3. Lymphatic vessels or ducts:

1. Formed by joining of lymphatic capillaries.
2. Numerous, present in various part of the body.
3. Made up of three layer – Tunica externa, tunica media and tunica interna.
4. Two main types of lymphatic ducts:

a. Right lymphatic duct:

• Smallest lymphatic duct. (length approximately 1.25 cm)
• Collects lymph from upper right side of the body.
• Carries lymph to the right sub-clavian vein.

b. Thoracic duct (Left lymphatic duct):

• Longest lymphatic duct (length approximately 38-45 cm).
• Carries lymph to the left sub-clavian vein.
• Collects lymph from the left part of head, neck, thoracic cavity and left arms.

4. Lymph nodes (Lymph Glands):

1. Masses of lymphatic tissue and connective tissue.
2. Small, oval bean-like structures.
3. Present in the neck axilla, thorax, abdomen and groin region.

5. Lymphatic organs:

1. Primary lymphatic organs → Red bone marrow and Thymus
2. Secondary lymphatic organs → Spleen (Largest component of lymphatic system) and Tonsils.