Human Immune System Flashcards
Innate immunity
Broad defenses against many kinds of pathogens
Barrier defenses
Physical barriers to success of pathogens
Includes mucus, skin oil, saliva, tears, and epithelial linings
Innate defenses
Cellular systems to stop pathogens
Neutrophils
Cells that attract to infected tissue and destroy pathogens
Macrophages
Large phagocytic cells that eat pathogens
Dendritic cells
Stimulate adaptive immunity
Eosinophils
Defense cells against multicellular invaders
Toll-like receptor (TLR)
Binds to special molecules characteristic of pathogens and not of the body
Histamine
Stored in mast cells, released at sites of damage to allow antimicrobial peptides and neutrophils to fix the damage
Septic shock
An extreme, systemic inflammatory response that can be fatal
Lymphatic system
Circulatory system that sends immune cells throughout the body
T cells
Lymphocytes that mature in the thymus
B cells
Lymphocytes that mature in the bone marrow
Epitope
Portion of antigen that binds to antigen receptor
Constant region
Same across all antigen receptors
Variable region
Different for every B cell
Antigen presentation
Process of host cell displaying antigen fragments using MHC, allowing cells to bind
Recombinase
An enzyme that facilitates many combinations of proteins to produce many types of receptors
Lymphocyte proliferation
Some become short-lived plasma cells, or effector cells, that act against the pathogen
Others become memory cells which quickly give rise to plasma cells when needed
Immunological memory
The use of memory cells to “remember” a disease, induces an intense immune response upon second exposure
Humoral response
Occurs in blood and lymph (B cells)
Cell-mediated response
Occurs with infected cells (cytotoxic T cells)
Helper T cells
Bind to presented antigens from antigen-presenting cells and release cytokines to stimulate T cell proliferation; also activates B and cytotoxic T cells
Cytotoxic T cells
Release granzymes to induce apoptosis in the target infected cell
B cells
Differentiates into memory B cells and antibody-secreting plasma cells
Antibody functions
Neutralization: blocks pathogen from entering a host
Opsonization: binding promotes phagocytosis by immune cells
Complement: forces a target cell to flood itself and burst
Immunization
Takes advantage of immunity by prompting primary response to a pathogen in a weak form, hopefully to encourage a greater response to the actual pathogen
Passive immunization
Antibodies transferred from immune animal to non-immune animal
Monoclonal antibodies
Large amounts of antibodies prepared from a cloned set of B cells
Blood and immune rejection
Blood antibodies can bind to cells from poorly-managed donations of blood, leading to adverse health effects
Organs and immune rejection
Immune system attacks MHC molecules from donated tissue, marking these MHC molecules as foreign
Allergies
Exaggerated immune responses that come about due to specific allergens; severe cases lead to anaphylactic shock
Autoimmune diseases
Body attacks its own molecules
Antigenic variation
Changes in epitope expression that can allow new strains of pathogens to dodge immunological memory
Latency
Pathogen entering an inactive state concealed from the immune system
HIV
A virus that infects cells of the adaptive immune system, also allowing it to hide from the immune system
