immunology

Overview of Lymphatic System

• The lymphatic system includes lymph nodes and lymphatic vessels that are integral to the immune response and fluid balance in the body.

Lymph Nodes and Vessels

• Lymph nodes: numerous structures that filter lymph fluid and play a role in activating the immune response.

• Lymphatic vessels:

  • Carry lymph fluid throughout the body.

  • Interconnect lymph nodes.

  • Eventually converge into larger ducts.

• Key duct: Thoracic Duct

  • Collects lymph from various regions and drains into the bloodstream (specifically into the superior vena cava).

Lymph Circulation

• The body circulates approximately 2 liters of lymph fluid daily.

• Lymph fluid:

  • Contains antigens that are captured and processed at different lymph node sites.

  • Essential for filtering out pathogens and debris.

Structure of Lymph Nodes

• Each lymph node has a protective layer: Capsule

  • Contains a subcapsular sinus on its surface.

• Macrophages are prevalent in the subcapsular sinus:

  • Engage in the phagocytosis of pathogens and debris present in the lymph fluid.

• Lymph nodes feature both afferent (incoming) and efferent (outgoing) lymphatic vessels:

  • Afferent vessels carry lymph to the node for filtering.

  • Efferent vessels allow filtered lymph to exit.

Follicles in Lymph Nodes

• Within the cortex of lymph nodes, there are specialized regions known as follicles:

  • Follicles serve as activated areas where B cells can proliferate and differentiate in response to antigens.

  • These regions are critical for mounting an effective immune response.