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38 Cards in this Set
- Front
- Back
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Compare nonadaptive and adaptive immunity**
Define: antigens |
Nonadaptive: nonspecific destruction of invaders + physical barriers (cilia, skin).
Adaptive: Memory of antigens that body was exposed to elicits a specific response to that antigen. Faster 2nd response. Antigens: Parts of foreign proteins, sugars, chemicals |
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What type of organisms is the innate system found in?
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Evolutionarily older, so found in fungi, plants, insects, primitive multicellular organisms.
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Examples of innate immune system cells. How do they work
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Basophils, eosinophils, neutrophils, NK cells, macrophages, dendritic cells, mast cells
Identifying and eliminating pathogens |
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4 major functions of innate immune system
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1. RECRUIT immune cells to site of infection using chemical factors/mediators, like cytokines.
2. ACTIVATE complement cascade to identify bacteria, activate cells, promote clearance of dead cells/antibody complex 3. IDENTIFICATION and REMOVAL of foreign substances in blood/tissue/organs/lymph via white blood cells/PHAGOCYTOSIS 4. ANTIGEN PRESENTATION - activate adaptive response |
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Name 2 major physical barriers used in innate defense
What do the cilia form in lungs, where? |
1. Skin - oil (sebum), fatty acids, salt.
2. Mucous membranes - trap, destroy pathogens, mucous sloughs off, microbes removed via cilia. Mucocilliary escalator. In trachea, bronchi, bronchioles. |
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What is the main chemical barrier in innate defense? Give 4 important characteristics
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Antimicrobial peptides (tears, saliva, etc)
1. Small, 12-17 amino acids 2. Cationic, can kill gram +/- 3. Form pores in cell membrane or work inside invader cell (destroy essential process, enzyme) 4. Produced in humans and animals (frogs!) |
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Describe the structure of antimicrobial peptides
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1. Positively charged residues (arginine, lysine, histadine)
2. Hydrophobic residues 3. Variable secondary structure (a-helical, extended, mixed, B-sheet) |
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What are the two main mechanisms antimicrobial peptides work by
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1. Membrane permeabilization - pore formation and gradient dissolution
2. Action on cytoplasmic targets - destroy some essential process or enzyme inside cell. Traverse membrane and bind to target. |
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Why don't antimicrobial peptides make pores in host cells?
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Microbes have more - charge than mammalian cells. (cationic, + charge of AMP attracted to - charge of microbe).
Eukaryotes have cholesterol in membrane, which disrupts AMP. |
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3 mechanisms by which bacteria form resistance to AMP.
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Neutralize membrane negative charge (S. aureus uses D. Alanine, L. lysine).
Make protease (proteolytic enzymes) to chew up AMP. |
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Name two things that happen when there is unregulated overproduction of antimicrobial peptides
What genre of disorders do they belong to? |
Atopic eczema, Roasacea
Autoimmune disease. |
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Where are immune cells (WBC) formed? What is the main precursor, what two things can they become?
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Bone marrow. Stem cells, turn into lymphatic precursor (T/B cells), or myeloid precursor (innate).
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Name 3 classes of WBC, and what fits under each. Know how they work
Note: what do monocytes differentiate into? |
1. Neutrophils, monocytes: use phagocytosis.
Note: monocytes can further differentiate into macrophage and dendritic cells 2. Granular - basophils, eosinophils, neutrophils, mast cells, NK cells - release toxins from granules 3. Lymphocytes, adaptive response - T cells produce specific response, B cells produce antibodies to bind antigens |
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What are 2 types of lymphoid organs, what happens in each?
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Primary: where lymphocytes mature (bone marrow, thymus)
Secondary: Where lymphocytes encounter antigens (spleen, lymph nodes) |
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**Steps of acute inflammatory response (innate immune response) **
Name 3 chemicals made (at end) which aid in inflammation |
1. Infected with invading microbe, bacteria enter tissue
2. Macrophage/dendritic cells in tissue sense invader's chemicals, migrate towards it, phagocytize, produce cytokines (peptides) and vasoactive factors. 3. Cytokines diffuse, come in contact with capillary. Capillary epithelium produces selectin proteins. 4. Selectins slow neutrophils down. Selectins interact with neutrophil carbohydrates to produce integrin, which binds with ICAM/VCAM, forcing neutrophils to really stick. 5. Vasoactive factors are produced by macrophages dealing with infection, capillaries loosen up so neutrophils can migrate into tissue --> site of infection 6. Neutrophils phagocytoze microbes, make chemicals like cytokines/chemokines to "sound alarm" that infection is occurring to body. 7. Other immune cells make chemicals like HISTAMINE, which also loosen tight junctions of capillaries. Cause fluid buildup (swelling). BRADYKININ - looses tight junctions, capillaries form PROSTOGLANDIN --> pain. |
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Mast cells
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Innate immune system
Granulocytes - release granules via degranulation to kill microbes or signal other cells. Release HISTAMINE (vasodilation, sneezing, recruits neutrophils, macrophages). Found in Connective tissue, mucosal membrane |
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Phagocytes
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Macrophage, dendritic cells, neutrophils.
Move towards microbe and phagocytizes it, may present parts on surface. |
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Explain how phagocytosis works. What is it important for besides immune function?
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Important for biological tissue development - removing old cells.
1. Phagocyte SENSES chemical signature of bacteria 2. ADHERES to bacteria, INGESTS in phagosome 3. PHAGOSOME + LYSOSOME --> PHAGOLYSOSOME 4. lysosome has enzymes to cleave macromolecules and make reactive oxygen species which kill microbe + break it up 5. some phagocytes present leftover microbe particle on surface as antigens (APC) |
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Macrophage
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Type of phagocyte
Very large, most efficient phagocyte. Circulating or found in tissues. Respiratory burst - release reactive oxygen/nitrogen species Cytokine production (alert other cells) |
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QUESTIONS
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what is a respiratory burst - what are reactive oxygen/nitrogen species??
Go over highlighted text in ppt (not mentioned in lecture) Are neutrophils both? WATCH VIDEO |
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Neutrophils
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Phagocytes
Most abundant, first responders PMNs (lobed nucleus) Circulating, also found in tissue Notorious for respiratory burst - reactive O2/N species, toxic substances Also granulocytes |
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Dendritic cells
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"branches"
Phagocytes Notorious for ANTIGEN PRESENTATION |
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Basophils
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not very common
GRANULOCYTES Release granules to certain stimulus, which have ANTIMICROBIAL and SIGNALLING properties recruited into tissue |
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Eosinophils
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Circulating GRNULOCYTES
Respond to cytokines, migrate to certain areas, recruited into tissue Granulocytes contain toxic proteins and free radicals to kill invading microbes |
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Natural killer cells
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Kill host cells that have become invaded/cancerous
Healthy cells: MHC1 Infected with virus, pathogen, cancer cell: stop producing MHC1 NK realizes this, make perforin proteins to make pores and lyse cells. |
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Name phagocytes, granulocytes
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Phagocytes: macrophages, neutrophils, dendritic cells
Granulocytes: mast cells, basophils, eosinophils, neutrophils |
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What is the process of extravasation?
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When neutrophils squeeze between capillary cells to attack bacteria in tissue.
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Where is bradykinin formed, what are its 3 roles?
What is the role of histamine? What does prostaglandin do? |
Damaged tissue forms bradykinin, promotes extravasation, stimulates mast cell degranulation, releases histamine
Histamine stimulates vessels to open, releasing platelets/plasma into area Prostoglandin stimulates free nerve endings, leads to itching/pain. Formation stimulated by bradykinin, in capillaries. |
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What are symptoms of inflammatory response?
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Pain, heat, swelling, altered function of infected site, redness. A non-specific response to wounds/infection.
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What is chronic inflammation, give 3 causes?
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Results from persistent presence of foreign object, which causes permanent tissue damage
1. Pathogens that are resistant to host defense (tuberculosis, biofilms) 2. Nonliving irritant material (wood splinter, asbestos) 3. Autoimmunity (Chron's disease) |
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How do some microbes avoid phagocytosis?
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Makes a capsule/slime layer.
Kills the phagocyte (s. aureus, pus in pimple) |
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pros/cons of fever and inflammation
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1. Helps phagocytosis efficiency while inhibiting bacteria
2. Brings in more blood flow, more antimicrobial agents 3. clot may isolate infected area 1. pain due to swelling 2. Cell (neutrophil) lysis can provide nutrients of other bacteria (Iron) 3. Microbes gain access to other tissue via blood 4. High fever is harmful (brain) |
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What is opsonization?
What prevents phagocytosis attack on host cells? |
When microbes are coated with antibodies, phagocytes are much more efficient.
The protein CD47 |
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Name 2 mechanisms used in phagosome-lysosome fusion to kill microbes
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Oxygen dependent (free radicals + nitrogen intermediates - OXIDATIVE BURST) and oxygen independent (lysosoyme, lactoferrin, defensins)
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How do innate immune cells recognize foreign invaders? 2 components, subtypes of each
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PRM present on phagocytes recognize microbial factors called PAMPs
Pattern recognition molecules: Toll-like receptors, mannose receptor, C reactive protein PAMPs: lipoteichoic acid, LPS, flagellin, peptidoglycan, foreign nucleic acids (dsRNA, unmethylated CpG) |
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How does the toll like receptor (TLR) work
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After PAMP binds to PRM - the toll like receptor - the TLR triggers a cascade, causing host cell to release cytokine, which attracts other immune cells to area
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What are the targets of TL2, TL4, TL5 (their PAMPs, and organism)
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TL2: peptidoglycan on gram + bacteria, zymosan on fungi
TL4: LPS in gram - bacteria TL5: flagellin in bacteria |
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What are cytokines?
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Small cell-signaling proteins released by many immune cells to coordinate in function with the body. Used for intracellular functions.
Proteins, peptides, glycoproteins. |
