Adaptive Immune System

Overview of the Immune System

• Focus on the lymphatic system, an integral part of the immune system, beyond just cells and molecules.

Lymphatic System

• The lymphatic system is akin to an open circulatory system found in some animals.
• Functions as a series of vessels that:
  • Collect tissue fluid (lymph) from extracellular spaces around tissues.
  • Return excess lymph back into blood circulation via veins near the neck.
• Structure:
  • Lymph vessels are open-ended, allowing them to collect excess tissue fluid from extremities.
• Plasma leaks out of blood vessels due to pressure from the heart, leading to:
  • Possible swelling if fluid accumulation continues in the tissues.
  • Lymph capillaries continuously pick up this excess fluid and return it to circulation, preventing edema.

Components of the Lymphatic System

• Lymph Nodes:
  • Act as filters for lymph fluid, housing and organizing immune cells such as lymphocytes and macrophages.
  • Sites where pathogens are often detected.
• Thymus:
  • Site for T lymphocyte production and maturation.
• Spleen:
  • The only lymph organ that handles both lymph and blood flow.
  • Crucial for detecting pathogens in the blood and for removing old red blood cells.
• Tonsils:
  • Clusters of immune cells that help filter pathogens from the lymph.

Functionality of the Lymphatic System

• Restoration of Fluid Balance:
  • Returns excess tissue fluid to prevent edema.
• Immune Response:
  • Lymphatic system plays a vital role in:
  • Producing T lymphocytes (from the thymus) and B lymphocytes (from the bone marrow).
  • Immune organs store lymphocytes and macrophages.
• Pathogen Detection:
  • Lymph nodes, spleen, and tonsils act as filters for detecting and engaging with pathogens entering the body.
  • They filter tissue fluid and blood, responding to infections.

Summary

• The lymphatic system is crucial for both fluid balance and immune defense by:
  • Collecting and returning tissue fluid to circulation.
  • Housing immune cells and aiding in the detection and filtration of pathogens to generate an immune response.