Innate Immunity Flashcards
What is first-line immunity?
Skin, mucous membranes, chemicals
What is second-line immunity?
Phagocytosis, complement, interferon, inflammation, fever
What is adaptive immunity?
Lymphocytes and antibodies
What are the three fundamentals of innate immunity?
Protective mechanism that exists before infection
Rapid responses encoded within the germline
Responses are typically identical upon repeat infection
What is inflammation?
Mobilizing bodily defenses at sites of infection
What are the physiological changes the inflammation causes?
Vasodilation
Increase in capillary permeability
Influx of immune cells to affected tissues
What are the four signs of inflammation?
Redness due to vasodilation and increases in blood volume
Heat due to increased blood volume bringing warmth to the area
Edema due to swelling caused by the accumulation of fluid from blood
Pain due to inflammatory mediators that trigger pain responses
How do the dilated capillaries help in immune response?
It helps more immune cells get to the affected area as well as slow down blood flow so that there is more time to contact the wall of the capillary and enter the affected tissue
How did Elie Metchnikoff find evidence for inflammation?
Poked a star-fish larvae with a thorn and observed the rapid localization of cells to the site of injury and the breakdown of the thorn by the cells
First observation of phagocytosis
What are the steps of inflammatory response?
Margination
Diapedesis
Chemotaxis
Phagocytosis
What is margination?
The migration of WBCs to the endothelium of the capillaries
What is diapedesis?
When WBCs squeeze through the epithelial layer
What is chemotaxis?
Attraction to chemokines
What do phagocytes do?
They ingest and destroy microbes via phagocytosis
What are the two processes done by the WBCs?
Chemotaxis = chasing down the microbes
Phagocytosis = eating of the microbes
What are the steps of phagocytosis?
Phagocytes detects and engages the microbe
Microbe engagement initiates cytoskeletal rearrangements that drive phagocytosis
The microbe is internalized in a specialized phagosome
The phagosome fuses with the lysosome to form a phagolysosome
Lysosomal enzymes destroy ingested microbes
Reactive oxygen and nitrogen intermediates destroy microbial proteins, genomes, and walls
What are the steps of macrophage development?
Macrophages arise from undifferentiated stem cells in the bone marrow
Some stem cells differentiate into short-lived monocytes that circulate in the blood
Inflammation recruits monocytes to sites of infection where they differentiate into resident macrophages
Resident macrophages are long-lived professional phagocytes that ingest large amounts of extracellular material
What is an important role of phagocytosis other than eliminating microbes?
Activating neighboring cells through the release of cytokines and chemokines
How are phagocytosed microbes killed?
By reactive oxygen species and NO
What are cytokines?
Secreted proteins that drive immune and inflammatory reactions