The lymphatic system

What are the functions of the lymphatic system?

• Removes interstitial fluid from tissues (helps maintain fluid balance)

• Transports white blood cells throughout the body

• Detects bacteria and other pathogens in lymph
  → Triggers lymphocyte proliferation in lymph nodes
  → Can cause swollen and tender nodes during infection

• Filters lymph through lymph nodes
  → Macrophages destroy microorganisms and debris

What are the methods of opsinisation?

• Opsonins coat the surface of a pathogen
  → Makes it easier for phagocytes to recognize and engulf it

• Main opsonins:

  • Antibodies (e.g. IgG)

  • Complement proteins (e.g. C3b)

• These act like "handles" that phagocyte receptors can grip

What is the function of complement cascade?

helps the immune system eliminate microbes and damaged cells.

Main functions:

• Removes microbes or damaged cells

• Promotes inflammation (by attracting immune cells to the site)

• Attacks and disrupts the cell membrane of pathogens or damaged cells (forming the membrane attack complex, MAC)

What are the downstream effects of complement cascade?

• Chemotaxis: Attracts macrophages and neutrophils to the infection site

• Opsonisation: Coats pathogens to enhance phagocytosis

• Cell lysis: Destroys pathogens by forming pores in their membranes (via the membrane attack complex)

• Leukocyte activation & migration: Stimulates immune cells and directs them to the affected area

• Agglutination: Clumps pathogens together to make them easier targets