____ immunity is always present in healthy individuals, is the first responder (has a rapid response), block entry of microbes, kills microbes that enter, and sends signals to alert adaptive immunity.
Can innate immunity be triggered by damaged host cells?
What are 5 things that innate immunity cannot/does not do?
1. does not recognize specific antigen structure 2. does not require prior exposure to antigen 3. does not become stronger (it will have the same reaction every time it encounters a pathogen) 4. does not react against noninfectious foreign substances or self-molecules/cells 5. does not form memory cells
What are epithelial barriers?
the first barrier that microbes encounter
What are 4 examples of epithelial barriers?
skin, respiratory mucosal epithelia, GI tract mucosal epithelia, and genitourinary tract mucosal epithelia
To cause infection, pathogens must cross ____ ____.
How can pathogens cross the epithelial barriers? (3)
1. they may adhere to the surface and infect the cell or cross the epithelial barrier 2. they may also colonize the epithelia 3. an unnatural breach in the epithelial surface may also let them in (ex: cut, wound, burn)
The ____ is a continuous physical and chemical barrier.
Loss of integrity of the skin causes increased risk of ____.
Epithelial cells produce ____ substances.
There are ____ in sweat to prevent the entry of pathogens.
The entry of normal flora is blocked by ____ ____.
The common portal of entry through the skin occurs through ____ ____ with microbes.
The respiratory tract has ____ and ____ that work together in the upper segment and surfactants in the lungs (lower segment).
mucus and cilia
The upper airway begins at the ____ and ends in the ____ and is protected by the ____ ____.
nose, bronchioles, mucociliary escalator
Mucus secreted by ____ ____ forms a fine layer lining the airway and trapping microorganisms
____ waft the mucus towards the mouth and nose, where trapped organisms are cleared by sneezing or coughing.
Mucus secretion is abnormal in ____ ____ and cilia are defective in ____ ____ ____.
cystic fibrosis, primary ciliary dyskinesia
The main defenses in lower respiratory tract are ____ secreted by ____ ____ ____.
surfactants, type II pneumocytes
There are about ____ m^2 of mucus membranes
Why might organisms trapped in mucus not be able to cause infection?
because they cannot adhere to cell surface
____ ____ move move in wave-like pattern toward mouth.
The ____ ____ removes pathogens via coughing and sneezing
____ is a substance that lowers surface tension and keeps alveoli from collapsing.
What is the immune function of surfactant?
binds to components of the cell surface of pathogens and causes them to agglutinate. That leads to destruction by phagocytes.
Is normal flora immune to the antimicrobial substances in the saliva?
The ____ motion of the GI tract helps clear things out of the system.
What common practice can disrupt the normal flora in both the GI tract and in the genitourinary tract, making these areas more prone to infection?
What are some features of the genitourinary system to keep microbes out?
1. Defensins and other antimicrobial products produced by epithelial cells and commensals 2. Constant flushing of urinary tract 3. Acidic vaginal pH and commensal bacteria 4. Spermine and zinc in semen are antibacterial (keeps the semen sterile) 5. Lactoperoxidase in milk (keeps milk sterile for the baby)
Are tears a feature of the innate immune system?
yes, because they wash away pathogens and contain antimicrobial substances
Epithelial cells produce antimicrobial chemicals called ____.
What are the 2 types of defensins and where else are they found?
alpha and beta; in neutrophil granules
Defensins have _____-spectrum antibiotic properties and have increased production in response to inflammatory _____.
_____ are alpha defensins that are produced by intestinal epithelial cells.
What are three types of epithelia-associated cells that are also B cells and T cells that are exceptions to the rules?
intraepithelial T lymphocytes (IELs), B-1 cells, mast cells
Intraepithelial T lymphocytes are associated with ____ epithelial cells, express ____ ____ of limited diversity, and recognize ____ structures.
barrier, antigen receptors, shared
Intraepithelial T lymphocytes also secrete ____, activate ____, and kill ____ cells.
cytokines, phagocytes, infected
B-1 cells are located in the ____ cavity and are similar to IELs. They can respond to microbes and toxins that breach the walls of the ____, and they produce natural ____ (IgM).
peritoneal, intestine, antibodies
Where are mast cells located?
under many epithelia and in serosal cavities
What do mast cells do?
secrete substances that mediate inflammation or release granules
Both the IELs and B-1 cells have more similarities to the ____ immune system.
____ and ____ are circulating phagocytes that are recruited to the site of infection.
monocytes and neutrophils
____ are phagocytes that are found in tissues.
Phagocytes ____, ____, and ____ microbes.
recognize, ingest, and kill
Recognition by phagocytes occurs through ____ ____ ____.
pattern recognition molecules
Pattern recognition molecules are only found on ____, not on ____ cells.
What are PAMPs?
pathogen-associated molecular patterns on pathogen
What are PRRs?
pathogen-recognition receptors on phagocyte
____ bind to ____ and the pathogen is internalized.
_____ is the process of getting a cell from the blood stream to the site of infection.
What are the 7 steps of phagocytosis?
1. chemotaxis and adherence of microbe to phagocyte 2. ingestion of microbe by phagocyte 3. formation of a phagosome 4. fusion of the phagosome with a lysosome to form a phagolysosome 5. digestion of ingested microbe by enzymes 6. formation of residual body containing indigestible material 7. either some of the peptides are held for antigen presentation or discharge of waste materials
Do antibodies kill anything?
no, but they will coat an organism (opsonization)
NK cells are a subset of ____. They are neither __ cells nor __ cells.
to protect against intracellular pathogens (mainly viruses)
NK cell recognition is mediated by ____ and ____ receptors.
activation and inhibition
Do NK cells kill immediately? Why or why not?
no, because they don't want to accidentally kill the wrong things.
What are some of the effector functions of NK cells? (7)
1. kill infected cells 2. operate in a similar manner to CTLs 3. have granules 4. eliminates reservoir of infection 5. can kill sooner than CTLs 6. IFNγ secreted by NK cells activates macrophages to destroy microbes/cells (positive feedback loop) 7. controls infection to allow T cell-mediated immunity to develop
What do the granules in NK cells contain and what do they do? (2)