A2 – Immunity Quiz

Study Notes

First Lines of Defense: Skin, eyelashes, ear hair, saliva (digestive enzymes), stomach acid, tears, earwax, mucus, and cilia act as barriers against pathogens.
Macrophages: Largest white blood cells (WBCs) that engulf and kill microorganisms, enhancing immune responses by stimulating other cells.
Helper T-Cells: WBCs that activate Killer T-Cells and B-Cells by collecting and sharing information about antigen shapes from macrophages.
B-Cells: WBCs that proliferate to produce antibodies specific to an invader’s antigens, releasing them into the bloodstream for neutralization.
Killer T-Cells: Hunt down and destroy bacteria and human cells infected with viruses, targeting specific antigens.
Suppressor T-Cells: Regulate and inhibit other immune cell activities to prevent overactivity post-infection.
Memory T-Cells and B-Cells: Dormant cells remaining after an immune response, ready to respond quickly if the same antigen is encountered again.

Pathogen Identification: Pathogens, including bacteria, viruses, fungi, and toxins, are recognized as foreign threats.
Acquired Immunity: Memory cells facilitate quicker immune responses upon re-exposure to previously encountered antigens, often preventing symptoms.

Vaccines: Introduce weakened or dead pathogens or their antigens to stimulate the immune system, leading to the production of antibodies.
Rapid Recognition: Immune system recalls pathogens faster on re-exposure, launching aggressive attacks to prevent illness spread.
Herd Immunity: Achieved when a significant portion of a population is immune, reducing overall disease transmission.

Tissue Matching: Close matching of donor and recipient antigens is essential to avoid rejection by the recipient’s immune system.
Immunosuppressant Drugs: Administered to transplant recipients to lower the risk of immune rejection.

Allergies: The immune system mistakenly attacks harmless substances (allergens).
Autoimmune Disorders: The immune system erroneously targets the body’s own cells, often treated with immunosuppressants.

Penicillin: Discovered by Alexander Fleming in 1929, this antibiotic remains a critical tool against bacterial infections, though ineffective against viruses.