week 7 - innate & intrinsic immunity Flashcards
mostly definitions
define interferon
IFN is a type of cytokine produced by virus-infected cells to inhibit viral replication in neighbouring cells and enhance immune responses. it plays a crucial role in innate immunity by signalling neighbouring cells to produce AVPs and activating immune cells such as NK cells and macrophages.
define complement
the complement system is a group of plasma proteins (produced by the liver) that enhance the immune response by promoting pathogen destruction, inflammation, and phagocytosis. it can be activated by the classical, lectin, or alternative pathway, leading to the formation of the MAC, which lyses target cells.
define iron-binding proteins
proteins that sequester iron to limit its availability to microbes, inhibiting their growth. e.g., transferrin, ferritin, lactoferrin, and hemoglobin, which help regulate iron homeostasis and contribute to immune defence.
define antimicrobial proteins (AMPs)
AMPs are small proteins that inhibit microbial growth by disrupting membranes, interfering with metabolism, or enhancing immune responses. e.g., defensins, cathelicidins, and lysozyme.
define NK cells
lymphocytes that target virus-infected cells and cancerous cells, inducing apoptosis using perforin and granzymes.
what are the 4 classic signs of inflammation?
1) rubor (redness): increased blood flow due to vasodilation
2) calor (heat): increased metabolic activity and blood flow
3) tumor (swelling): fluid accumulation from increased vascular permeability
4) dolor (pain): stimulation of pain receptors by chemical mediators like bradykinin and prostaglandins.
define fever
an abnormally high body temperature due to a reset of the hypothalamic thermostat, leading to an elevated set point. it enhances immune responses by intensifying the effects of IFNs (increases AVP production), inhibiting microorganism growth, and speeding up metabolic reactions to aid in tissue repair.
define hemostasis
hemostasis is the process that stops bleeding when blood vessels are injured. it involves three mechanisms: vascular spasm, platelet plug formation, and coagulation.
define vascular spasm
the immediate, reflexive contraction/constriction of blood vessels at the injury site, to limit blood flow to the area, minimizing blood loss.
define fibrinogen
a soluble plasma protein produced by the liver that serves as a precursor to fibrin. it plays a key role in blood clotting by helping form a stable clot.
define fibrin
an insoluble protein formed when thrombin cleaves fibrinogen during the coagulation cascade. it creates a mesh-like network that stabilizes the platelet plug and strengthens the blood clot.
prothrombin time (PT) test
-coagulation test (measures the time it takes for blood to clot)
-assesses the extrinsic and common pathways of coagulation
-used to monitor coumarin therapy
activated partial thromboplastin (aPTT) test
-coagulation test (measures the time it takes for blood to clot)
-assesses the intrinsic and common pathways of coagulation
-used to monitor heparin therapy
heparin
-anticoagulant
-enhances the activity of antithrombin III
-has a rapid onset and is administered intravenously or subcutaneously
coumarin (e.g., warfarin)
-anticoagulant
-inhibits vitamin K-dependent clotting factor synthesis in the liver
-has a delayed onset and is taken orally for long-term anticoagulation
define macrophages
large phagocytes that can be fixed or wandering that function to engulf pathogens, present antigens to T cells, and secrete cytokines to regulate immune responses.
define neutrophils
the most abundant WBCs, specializing in rapid response to infections by engulfing pathogens and releasing enzymes.
