Immunology: Phagocytosis, Immunity & Inflammation

• Phagocytosis is the process where phagocytes engulf and digest pathogens, debris, or particles.
• Phagocytes move via chemotaxis.

Complement Pathway

• The complement system enhances the ability of antibodies and phagocytic cells to clear pathogens.

Goal of Inflammation

• Inflammation eliminates the cause of cell injury, clears damaged cells, and establishes tissue repair.

Body Temperature Regulation

• The hypothalamus regulates body temperature, including fever.

Active vs. Passive Immunity

• Active Immunity: The body produces antibodies in response to an antigen, either naturally through infection or artificially through vaccination.
• Passive Immunity: The body receives pre-formed antibodies, either naturally from a mother or artificially through antibody injections.

Advantages of Fever

• Fever inhibits pathogen growth and enhances immune responses.

Cytokines

• Cytokines are signaling proteins released by cells, especially during infection.

Phagocytosis Phases

• Chemotaxis: Phagocytes move toward the infection site.
• Adherence: Phagocytes attach to the pathogen.
• Ingestion: The pathogen is engulfed into a phagosome.
• Digestion: The phagosome fuses with a lysosome to form a phagolysosome, breaking down the pathogen.

Active Immunity Examples

• Natural: Recovering from an infection triggers the body to produce its own antibodies.
• Artificial: Receiving a vaccine stimulates the body to produce antibodies.

Passive Immunity Examples

• Natural: Antibodies pass from mother to fetus, providing temporary protection.
• Artificial: Injection of antibodies gives immediate protection.

Granulocytes

• Neutrophils: Most abundant, respond to bacterial infections.
• Eosinophils: Combat parasitic infections and involved in allergic reactions.
• Basophils: Release histamine during allergic reactions, defend against parasites.

Key Phagocytic Cells

• Neutrophils: Rapid responders to infection.
• Macrophages: Engulf pathogens and present antigens to T cells.

Phagocytosis - Definition and Role

• Definition: The cellular process of engulfing and digesting particles.
• Role: Clears pathogens and debris, aiding in immune defense.

Normal Flora

• Normal flora are beneficial microorganisms on body surfaces, preventing infections by outcompeting pathogens and producing inhibitory substances.

Innate vs. Acquired Immunity

• Innate Immunity: Non-specific, immediate defense mechanisms present from birth.
• Acquired Immunity: Specific, slower responses developed after exposure to antigens, involving memory cells.

Hapten

• A hapten is a small molecule that elicits an immune response when combined with a larger carrier.
• Example: Penicillin acts as a hapten, binding to proteins and potentially causing allergic reactions.

Vaccination

• Definition: Administration of antigenic material to stimulate immunity.
• Purpose: To prevent diseases by inducing immunity.
• Components: Antigens, adjuvants, stabilizers, and preservatives.

Body's Defense

• The body uses innate and adaptive immune mechanisms to identify, target, and eliminate pathogens.