Lecture Notes: The Lymphatic System

Overview of Lymphatic System

• Lymphatic System: Consists of lymph, a clear pale yellowish fluid.
• Formation: Fluid from blood vessels seeps into the interstitial space, forming lymph.
• Volume: About 3 liters of fluid daily is processed by the lymphatic system.

Functions of the Lymphatic System

1. Drainage of Excess Interstitial Fluid
   • Returns fluid to blood to maintain blood volume.
2. Transport of Dietary Fats
   • Fats are absorbed in the small intestine into the lymphatic system.
3. Immune Responses
   • Lymphocytes within lymph filter and respond to pathogens.

Anatomy of the Lymphatic System

• Lymphatic Vessels: Start as lymphatic capillaries, progress to vessels, trunks, and ducts.
• Superficial vs. Deep Vessels: Found near skin or running alongside organs, arteries, and veins.
• Lymphatic Ducts: Thoracic duct and right lymphatic duct empty lymph into the subclavian veins.

Lymphatic Vessels Structure

• Capillaries: Closed-end structures beginning the lymphatic pathway.
• Vessels: Larger, with thin walls and valves to ensure one-way movement.
• Trunks and Ducts: Larger structures formed by merging vessels.

Differences from Circulatory System

• Lymphatic System: One-way system starting at capillaries and ending in veins.
• Blood System: Circular with continuous flow.

Lymphedema

• Definition: Swelling due to blocked lymph vessels.
• Causes: Blockages from surgery, trauma, or cancer.
• Treatment: Compression, exercise, massage; sometimes persistent.

Primary Lymphatic Organs

1. Red Bone Marrow
   • Produces B and T cells; involved in hematopoiesis.
2. Thymus
   • Site for T lymphocyte maturation; large in children.

Secondary Lymphatic Organs

1. Lymph Nodes
   • Filter lymph and are sites of immune cell activation.
   • Sites: Neck, armpits, and groin.
2. Spleen
   • Largest lymphatic organ, filters blood.
   • Contains white and red pulp for immune function and blood processing.
3. Lymphatic Nodules
   • Found in mucous membranes; include tonsils.

Tonsils and Related Issues

• Tonsils: Lingual, palatine, and pharyngeal.
• Tonsillitis: Inflammation often due to infection.
• Tonsillectomy: Surgical removal in cases of chronic tonsillitis.

Clinical Connections

• Lymphedema: Swelling due to fluid retention in interstitial space.
• Splenectomy: Removal of the spleen, leading to increased infection risk.

Summary

• The lymphatic system is essential for fluid balance, fat transport, and immune responses.
• Various structures work together to filter lymph and protect the body from pathogens.
• Understanding the lymphatic system's structure and function is crucial for recognizing related disorders.