The First Line of Defense Flashcards
Name the five ways a pathogen can spread.
Air, Saliva, Food/water, Vector (bugs), and Contact
What do Viruses recognize for entry?
They can only recognize specific receptors for entry, therefore they must get to the right cell for infection
What are the two locations of a pathogen
-Extracellular: interstitial spaces, blood, lymph
-Intracellular: Cytoplasmic and Vesicular
List the three direct mechanisms of tissue damage by pathogens
Exotoxin production, endotoxin, and direct cytopathic effect
Who usually secretes exotoxins and what is their purpose
Usually secreted by bacteria with the main purpose of damaging the host by a release of toxin
Describe endotoxins
-A normal part of the bacteria
-upon death, endotoxins are released
-immune system responds too strongly
-lipopolysaccharide gram-negative
-Lipotechoic acid gram-positive
Describe the direct cytopathic effect
Virus lyse cells upon exit, the virus will use up resources, disrupt membrane on exit and eventually kills cells
List the three indirect mechanisms of tissue damage by pathogens
Immune complexes, anti-host antibody, and cell-mediated immunity
Describe Immune Complexes
-Multiple antibodies and antigens bound (glutination)
-Can take on large sizes
-can accumulate and cause health problems (get stuck and are hard to get rid of)
Describe anti-host antibody
-generates an attack on host cells (the pathogens have antigens similar to host antigens)
Describe cell-mediated immunity
-will kill the infected cells
-important for clearing viral-infected cells, but still kills a cell (Natural killer cell)
What are the three methods for epithelial barriers
Mechanical (flow), Chemical (kills pathogen), Microbiological
What is the activity of antimicrobial peptides (AMPs)
They are small peptides that kill antigens
Where are AMPs found
in the lipid layer
How does sweat play a role in immunity?
Create a flow (mechanical) to wash the pathogens off, it also has a high salt and is slightly acidic making it undesirable for most bacteria
What does internal epithelial mucus contain
mostly water, glycoproteins called mucins, salts, and AMPs (both salt and AMP help prevent the growth of bacteria
Describe Mucins
It is a protein that is extremely glycosylated (lots of sugars attached), can be membrane-bound or free, interacts with water and creates barrier
What cell creates mucin
Goblet cells found throughout mucosal epithelium
What moves the mucus with trapped pathogens to the esophagus
Cilia
What is the purpose of gut epithelia
-Contains digestive enzymes and bile salts
-paneth cells in crypts
What is Microbiota
The normal, commensal microbes found in/ around an organism
What is the role of microbiota
-does not infect the host and might actually help
-can prevent dangerous pathogens from colonizing
-secrete useful molecules
What are the three main classes of defensins
alpha-defensin, beta-defensin, and theta defensin and all are stabilized by disulfides
What is role of defensins
AMPs that form a pore
What are cathelicidins
Same function as defensins, single helix
What are Histatins
key saliva AMPs, histidine rich, and has strong anti-fungal properties
What is lectin
a protein that binds carbohydrates specifically (not a metabolic protein)
What are the three ways cells prevent the pore-forming of their own membrane?
-Keep antimicrobial peptides in granules (no access to cells)
-keep them inactive until needed
-evolve then not to bind host lipids
