Term
| General characteristics of the immune system (3) |
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Definition
1. It defends the body against infectious agents
2. It is mostly non-self reactive
(...but may be in some cases such as autoimmunity and it allows this b/c never know when it might be invaded by an antigen with proteins on surface very similar to self)
3. Tightly regulated |
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Term
| Cut scenario: First thing that happens when you cut yourself |
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Definition
- You've broken the barrier/first immune defence
- Neuropeptides are released |
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Term
| Cut scenario: What happens in response to the release of neuropeptides? |
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Definition
- PAIN!
- and activation of mast cells |
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Term
| Cut scenario: After mast cells are activated, what happens? |
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Definition
- BLEEDING!
- clotting factors become involved |
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Term
| Cut scenario: what do clotting factors do? |
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Definition
| They cleave complement C3 into C3a and C3b |
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Term
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Definition
- part of host defence
- it complement the activity of antibodies and phagocytes in clearing pathogens
- it is a cascade of serum proteins |
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Term
| How does complement work? |
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Definition
| the proteins bind to pathogens, poke holes in htheir outer surfaces and cause death! |
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Term
| C3a activates _____. C3b activates ____. |
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Definition
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Term
| C3a binds ____. C3b binds ____. |
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Definition
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Term
| Cut scenario: After complement is activated, then LPSs come into play. What does LPS mean/what do they do? |
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Definition
-Lipopolysaccharides
- on the surface of bacteria --> protection, and also provide permeability to only let low MW molecules and hydrophilic molecules in
- stimulate the immune response |
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Term
| Cut scenario: After LPS, CPG motifs come out to play... what are these/what do they do? |
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Definition
C=cytosine, p=phosphodiester link, G=guanine
- bacteria have runs of cytosine and guanine --> rare in humans
- therefore, stimulus for inflammatory cells |
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Term
| What are PAMPs and what have we discussed so far that are PAMPs? |
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Definition
pathogen associated molecular patterns
- LPS and CpG motifs |
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Term
| What are DAMPs? Give examples. Why do they matter? |
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Definition
damage associated molecular patterns
- inflammatory cells also respond to molecules associated with tissue damage
- ex: heat shock proteins and hyaluronan fragments |
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Term
| What are TLRs? What do they bind? Where are they located |
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Definition
- toll like receptors --> they recognize patterns associated with infections and inflammation
- they bind DAMPs (LPS and CpGs)
- mast cells and macrophages |
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Term
| True or false: TLRs recognize specific antigens. |
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Definition
| FALSE - they don't... they just know there's some damage happening |
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Term
| What are some characteristic of MAST CELLS? |
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Definition
- found only in tissue
- not tissue basophils
- originally only ascribed to allergic response
- but we know they are involved in inflammation and immune response |
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Term
| What are some characteristics of monocytes/macrophages? |
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Definition
- they are important early responders in infection
- involved in both acute and chronic inflammation |
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Term
| Monocytes are found in ____. Macrophages are found in ____. |
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Definition
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Term
| What do activated mast cells secrete? |
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Definition
histamine! Within seconds.
prostaglandins! takes longer |
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Term
| Explain the effects of histamine release. |
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Definition
- endothelial cells that line blood vessels pull apart creating tiny spaces btw
- Increased vascular permeability --> swelling and pain
- Increased vasodilation --> redness and heat |
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Term
| What are the three ways to activate complement? |
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Definition
1. Classical
2. Alternate
3. Lectin |
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Term
| Explain classical activation of complement. |
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Definition
- it involves antibody!
- activated by the Fc portion of an immunoglobulin in an antigen-antibody complex |
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Term
| Explain alternate activation of complement. |
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Definition
- happens by spontaneous cleavage
- in a site of inflammation, C3 comes out of circulation and into the tissue where it is spontaneously cleaved to C3a and C3b |
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Term
| Explain lectin activation of complement. |
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Definition
| any group of proteins (especially plants_ that are not antibodies and don't originate in an immune system that bind specifically to carbohydrate-containing receptors on cell surfaces |
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Term
| What are the functions of complement? |
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Definition
- Target lysis of bacteria and viruses
- Target neutralization (preventing neutralization)
- Enhance phagocytosis
- Inflammation |
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Term
Describe the activity of complement and antibody based on whether you've:
1. seen the bug before
2. have no seen the bug before |
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Definition
1. complement will bind directly and so will antibody
2. complement will bind directly but antibody won't because it doesn't recognize it |
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Term
| What is the result of antibody binding to bugs it has seen before? |
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Definition
It activates killing pathways:
- antibody mediated complement and phagocytic pathways |
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Term
| What enhances phagocytes? (opsonization for phagocytosis) |
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Definition
- Antibody! Macrophages have Fc receptors that bind Ab on the bacteria
- Complement! Macrophages have receptors for C3 |
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Term
| Explain vesicle acidification |
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Definition
once bacteria gets taken in by macrophages, it gets taken into a phagosome where the pH is very low.
- not many things can exists, so bacteria can't replicate
- enzymes, which work well at low pH, are released into the phagosome |
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Term
| Explain bacterial phagocytosis |
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Definition
- a microbe gets taken in
- it is put into a phagosome
- a lysosome merges with the phagosome to come a phagolysosome
- the bug gets broken down
- digested material in a vesicle is no longer infectious
- it gets put out (like garbage) |
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Term
| What are reactive oxygen intermediates? |
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Definition
superoxide anion (O2-)
hydroxyl radical (OH)
hydrogen peroxide (H2O2)
hyperchlorite (ClO-) |
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Term
| What are reactive nitrogen intermediates? |
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Definition
Nitric oxide (NO)
Nitrous acid (HNO2) |
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Term
| Back to the cut scenario: What kind of reinforcement do macrophages call in? |
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Definition
| cytokines (IL-1 and TNF) chemokines (IL-8) |
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Term
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Definition
| movement of a cell up a chemical gradient |
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Term
| IL-1 and TNF cytokines increase expression of ____. What role do these play? |
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Definition
| Cell adhesion molecules! They grab circulating leukocytes and direct them through the endothelium to the site of inflammation |
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Term
| What is another name for neutrophils and why? |
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Definition
| Polymorphonuclear cells - because of their shape |
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Term
| What are some characteristics of neutrophils? |
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Definition
- they are the most common WBC
- they are early responders to bacterial infections
- they are highly phagocytic in tissue
- involved in tissue remodelling (such as scarring) |
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Term
| What do neutrophils respond to (3)? |
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Definition
DAMPs
Complement activation
opsonized bacteria |
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Term
| Neutrophils are involved in direct and indirect killing by.... |
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Definition
| NO, MPO, H2O2, proteases, superoxide and defensins |
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Term
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Definition
| stimulate processes that results in more neutrophils |
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Term
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Definition
| Netosis! this is when neutrophils release large strands of DNA in the local environment. |
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Term
| ____ cells are the link between innate response in the skin and adaptive response in the lymph node. |
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Definition
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Term
| True or false: lymphatic drainage involves a two way valve |
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Definition
| FALSE! A one way valve, where lymph flows up the gradient but doesn't flow back down. |
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Term
| What happens if you block the lymphatic system? |
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Definition
| improper flow, resulting in swelling |
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Term
| Axillary nodes drain the __ and ___. |
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Definition
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