What are the three main branches of the immune system?
Innate immunity (non-specific, rapid), Humoral immunity (B cells, antibodies), and Cell-mediated immunity (T cells).
What is the “Swiss cheese” analogy for the immune system?
Each layer of defense has weaknesses (holes); illness occurs if a pathogen passes through all aligned holes.
What is the “castle defense” analogy for the immune system?
Walls = physical barriers, Soldiers = innate immunity, Snipers = adaptive immunity.
Name three examples of physical barriers in immunity.
Skin, mucous membranes, stomach acid (also: tears, saliva, cilia, gut flora).
What type of immunity are neutrophils part of, and what do they do?
Innate immunity; they phagocytose bacteria, release enzymes, and form NETs (DNA traps).
What immune cells are the main tissue-resident histamine releasers?
Mast cells.
What is the role of eosinophils?
Defend against parasitic infections and contribute to allergic reactions.
What innate immune cells connect to adaptive immunity by presenting antigens?
Macrophages and dendritic cells (antigen-presenting cells).
What are Pattern Recognition Receptors (PRRs)?
Receptors on innate cells that detect broad pathogen patterns (PAMPs).
NK cells are lymphocytes but function as part of which immune branch?
Innate immunity.
Which cells produce antibodies?
B cells (plasma cells).
What are the three main functions of antibodies?
Opsonization, agglutination, and neutralization.
What is the difference between Helper T cells and Cytotoxic T cells?
Helper T cells activate and coordinate immune responses; Cytotoxic T cells kill infected or cancerous cells.
What immune cells provide long-term immunity after infection or vaccination?
Memory B cells and Memory T cells.
What is the difference between humoral and cell-mediated immunity?
Humoral = antibodies in fluids (B cells);
Cell-mediated = T cells killing infected/abnormal cells.
What molecules are the main “language” of immune cell communication?
Cytokines (e.g., interleukins, interferons, TNF).
What does histamine do in an immune response?
Causes vasodilation, increases vascular permeability, bronchoconstriction, and mucus production.
What are the four cardinal signs of inflammation?
Heat, redness, swelling, pain.
What is a cytokine storm?
Excessive cytokine release causing uncontrolled inflammation, vascular leak, tissue damage, and risk of MODS.
Which antibody type is involved in allergic reactions and binds to mast cells?
IgE.
Where do B cells develop and mature?
Bone marrow.
Where do T cells mature?
Thymus.
What do lymph nodes do?
Filter lymph, present antigens, and activate lymphocytes.
Which organ filters blood, removes old red cells, and activates immune responses?
Spleen.
