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20 terms

BIO269 - Immunology - Innate Defenses

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innate defenses
defenses that you're born with and are the same for every human being; can be either surface or internal
surface innate defenses include
the skin and musosae
mucosa
the innermost layer of the intestine, epithelial, a barrier between bacteria and the rest of the body
internal innate defenses include
phagocytes, fever, NK cells, antimicrobial proteins, inflammation
immunology is split into ___ systems:
2; innate, adaptive
adaptive defenses include
humoral immunity (b cell) and cellular immunity (t cell)
how does the integument act as an innate defense?
(1) the fact that its multilayered makes it more difficult for bad things to get through (2) the stratum spinosum secretes keratin to stop bacterial enzymes and toxins
how do epithelial membranes act as innate defenses?
(1) acidic secretions & stomach's acidic mucosa keep the pH low enough that most bacteria won't thrive (2) saliva contains lysozymes to kill bacteria (3) mucus in the respiratory tract traps inhaled bacteria from progressing (4) mucus in the digestive tract retards bacteria's burrowing into the walls
how does phagocytosis work, exactly?
the phagocytic organelle engulfs the target substance and forms a phospholipid membrane (vesible) around it to isolate it; the membranes of the vesible and lysozome bind together to let the lysozome contact the target without exposing the rest of the cell; the lysozome digests it and then fuses with the membrane for exocytosis, where the antigens (end products) are presented to other cells for complete disposal
natural killer cells
lymphocytes (5-10%) that are non-specific sugars, trying to kill anything whose surface doesn't have recognizable proteins
how do natural killer cells work?
when they detect a foreign cell, they attack the cell's membrane releasing perforins, making holes in the membrane; ECF enters, causes it to burst; also causes nucleus to disintegrate if there is a nucleus
signs of inflammation
redness, heat, swelling, pain, impairment of function (immobilization)
the inflammatory process
receptors on the cell surface release chemicals (histamine, kinins) to begin the process, which causes small blood vessels to dilate (redness & heat from more blood to the area) and capillaries to increase permeability, which leads to edema (fluid leaks out via fenestrations to ECF, upsetting its homeostasis with infected cell, so the fluid then goes into the cell) and, thus, pain
how does inflammation aid in the healing process?
the extra fluid dilutes the harmful substances, and the extra blood flow delivers more oxygen and nutrients
what follows inflammation?
phagocyte mobilization
phagocyte mobilization
a process after inflammation that involves a large increase in neutrophil concentration (4-5x), which all aggregate in the blood vessel and marginate (adhere to the wall), leaving via diapedesis and finding the infection via chemotaxis
how do viruses work?
viruses are made up of either DNA OR RNA, plus protein, so they can't self-replicate; they need to use the host's "cellular machinery" (whichever DNA or RNA they're missing)
interferons
antimicrobial proteins that interfere with viral replication
how do interferons work?
the virus enters host cell 1 and starts replicating, triggering the interferon genes; but cell 1 is a lost cause, so the interferons go out into the ECF, where other cells can detect them and start making their own antiviral proteins, which block the virus's access to ribosomes, which they need to replicate; eventually, they die off
how does fever work as an innate defense?
bacteria release exogenous pyrogens (foreign chemicals) which trigger leokocytes to release endogenous pyrogens (familiar chemicals), which trigger the hypothalamus to release prostaglandins, a hormone that causes shivering (targeting skeletal muscle) to increase body temperature, in the hopes that it will go out of the bacteria's operational range; meanwhile, the liver and spleen gather up all iron and zinc, which the bacteria need for replication, and metabolism speeds up