Immunology: Host Microbe Interactions from the host perspective Flashcards
what are most bacteria inhabiting the world
harmless or non disease causing possibly even beneficial
what is the main goal of the immune system
to differentiate self from nonself and neutralize potential pathogenic organisms or substances
what are the two broad types of immunity
innate immunity and adaptive immunity
what are the characteristics of innate immunity
the front line defense, present at birth, barriers to infection (skin and mucous membrane), specialized cellular defenders (mediate sterilization of tissues, nonspecific responses to destroy invading cells
why does skin work as a physical barrier defense / why does skin work as a chemical defense
is a very tight connective tissue, has layers of regenerating epithelial cells, dead cells fall off and remove attached bacteria (continuously shedding) / acidic, dry, salty, and pops bacterial cells - sebum oil lowers pH, keratin repels water causes a decrease in water availability, salt from perspiration causes osmotic stress, antimicrobial peptides-disrupt microbial membranes
what are antimicrobial peptides / how many classes of defensins are there
defensins (small, antimicrobial, cationic peptides), destroy invaders cell membrane / two
how is are mucous membrane physical barriers
typically composed of a single layer of cells (not a large surface), tight junctions make a physical barrier between individual cells, constantly bathing in secretions (mucous, tears, saliva), provides means to move bacteria away from surface
how are mucous membranes chemical defense
they are acidic, nutrient deprived, pop bacterial cells - things like stomach acid have very low pH, lactoferrin sequesters iron, antimicrobial peptides disrupt membranes, and lysozymes degrade peptidoglycan
what happens when primary defenses are breached (physical wound)
interior defenses keep tissues sterile using specialized cells that look for bacteria
what is the step process of the innate immunity
cells sense the presence of microbes, the alarm is broadcast, specialized cells are recruited (phagocytes) and the tissue is then sterilized and healed
what does our cell use to sense the bacteria / what is in the bacteria that we sense
we use pattern recognition receptors (PRRs) / Microbe-associated molecular patterns (MAMPs) are the unique structure in microbes that immediately tag them as foreign
what are the two classes of PRRs / what do they do / where are they found
Toll-like receptors (TLRs) and NOD-like receptors (NLRs) / trigger an alarm that there is an invader / TLRs are found on the surface of the cell and NLRs are found in the cytosol of the host cell
what do TLRs and NLRs do / what are cytokines
enduce the production of cytokines / secreted proteins that signal other cells the presence of bacteria
what do cytokines do
recruit phagocytes to the site of infection, induce cellular activation - prime cells to respond and to detect infection (express more PRRs on cells), increase phagocyte killing power
what do phagocytes do / what are the two main phagocytes
they recognize and engulf foreign cells / macrophages and neutrophils
