immunitty

• Passive immunity occurs when antibodies or sensitized lymphocytes are transferred from another individual.
• A human body has 3 lines of defence
• The first line of defense is the skin, mucous membranes, and secretions
• The third line of defense involves adaptive immune responses that include humoral and cell-mediated immunity
• The second line of defense includes phagocytic cells such as neutrophils, macrophages, dendritic cells, natural killer (NK) cells, and eosinophils
• first line of defence
• 1. Physical Barriers:

  • Skin: Acts as a tough barrier preventing pathogens from entering.
  • Mucous Membranes: Produce mucus to trap and block pathogens.

  1. Chemical Barriers:

  • Stomach Acid: Kills many pathogens in the digestive system.
  • Enzymes and Antimicrobial Substances: Found in saliva, tears, and bodily fluids to neutralize pathogens.

  1. Microbiota:

  • Normal microorganisms on the skin and in the digestive tract compete with and inhibit harmful pathogens.
• second line of defense in the immune system includes:

  1. Phagocytes: White blood cells that eat and digest pathogens.
  2. Inflammatory Response: Causes redness, warmth, and swelling to fight infections.
  3. Complement System: Proteins that mark pathogens for destruction.
  4. Interferons: Proteins signaling nearby cells to boost antiviral defenses.
• Key components of the adaptive or acquired immune system include:

  • Lymphocytes (T cells and B cells)
  • Memory cells
  • Antibodies
  • Cell-Mediated and Humoral Immunity
• T cells recognize and destroy infected cells directly
• B cells produce antibodies that target and neutralize specific pathogens
• After an infection, some lymphocytes become memory cells, providing long-term immunity by "remembering" how to fight specific pathogens
• Antibodies are Y-shaped proteins produced by B cells that bind to and neutralize specific pathogens, playing a crucial role in immune defense
• Cell-mediated immunity involves T cells directly attacking infected cells
• Humoral immunity involves B cells and antibodies in the bloodstream combating pathogens
• The adaptive immune system tailors its response to specific threats and "remembers" how to combat them in the future, providing long-lasting protection