Immune System: Second Line of Defense Flashcards

Second Line of Defense in the Immune System

• The second line of defense represents the body's innate immunity, providing a non-specific response to infections.
• Key components include recognition, fever, inflammation, complement proteins, phagocytosis, and interferons.

Phagocytic Cells

• Phagocytic cells engulf and enclose microbes within vacuoles to neutralize threats.
• Macrophages are a significant type of phagocytic cell, effective at destroying extracellular antigens.

Inflammation

• Triggered by damaged tissues and basophils releasing chemicals that attract immune cells such as macrophages.
• Characteristics of inflammation include redness, swelling, warmth, pain, and potential loss of function.

Role of Fever

• Fever raises body temperature, enhancing the efficiency of immune cells and inhibiting bacterial growth.
• It serves as a systemic response to infections, allergies, and cancers, with initiation by pyrogens that reset the hypothalamic thermostat.

Function of Complement Proteins

• Circulate in blood plasma, assisting in immune response by marking microbes for destruction and forming pores in foreign cells.
• The complement protein cascade includes initiation, amplification, cascade, polymerization, and membrane attack stages.

Surveillance Mechanism

• White blood cells (WBCs) continually monitor for foreign agents and infections, acting as a surveillance system.
• Phagocytes perform vital roles of surveying, ingesting, and eliminating pathogens, while also extracting immunological information.

Phagocytosis Process

• Involves five steps: chemotaxis (movement toward infection), adherence, ingestion, digestion, and killing of pathogens.
• Cytokines released during phagocytosis trigger the activation of the body's third line of defense.

Benefits of Fever

• Inhibits growth of temperature-sensitive microorganisms and reduces available iron, a vital nutrient for bacteria.
• Increases metabolism and promotes protective processes within the body.

Complement Protein Pathways

• Include classical pathway (most commonly used), MB-Lectin pathway, and alternative pathway, enhancing the effectiveness of antibodies and phagocytic cells in clearing microbes.

Test your knowledge of the innate immune system with these flashcards focusing on the second line of defense. Explore key concepts such as recognition, fever, inflammation, and the role of complement proteins and phagocytosis. Perfect for students of biology or anyone interested in understanding how our bodies fight infections.