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25 Cards in this Set

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What are the 3 lines of defense the body has against pathogens? Which are specific? Non specific?
1. 1st line: skin, mucous membranes, chemicals (non-specific)
2. 2nd line: phagocytosis, complement interferion, inflammation, fever (non-specific)
3. 3rd line: luymphocytes, antibodies (specific)
What are the physical and chemical components of the 1st line of defense?
Physical main components: skin and mucous membranes
Chemical components: Dermicidins (produced by dermal cells), perspiration (salt, lysozyme-destroys cell walls), and sebum (oil) which lowers the pH of the skin
How do the mucous membranes participate in defense?
They line all cavaties open to the outside environment.
They have 2 layers:
1. Epithelium
2. Deeper Connective layer (supports epithelium)
What other secretions and activities contribute tot he first line of defense
Microbial anatagonism - normal flora compete with potential pathogens by:
1. Secrete antimicrobial substances (tears, sweat, urine)
2. Consume nutrients (makes them unavailable to pathogens)
3. Change pH (Exp: lactobacillus in the vagina)
4. Stimulate 2nd line of defense
5. Provide vitamin to host - promotes overall health
What are the 2 main groups of leukocytes?
Agranulocytes (don't contain granules in the cytoplasm) and granulocytes
Name the 3 types of intereron and describe their function. Which are produced during early infection, and which are produced later?
Interferons are proteins released by host cells which nonspecifically inhibit viral spreading and are most effective against RNA viruses.
Early stages:
Alpha and Beta: Alpha - secrete Beta-interferons when infected with viruses and then they bind to interferon receptors on the cytoplasm membranes of neighboring cells.
Late stages:
Gamma - produced by activated T and NK lymphocytes. Helps protect body against viral infections and stimulated phagocytic activity.
What are the 3 main types of granulocytes and what do they do?
1. Basophils (0.5%) - release histamine and mediate inflammation; stain with basic dyes (methylene blue)
2. Eosinophils (2-4%) - phagocytic cells capable of diapedsis (squeeze through cells that line capallaries and move out of blood into other parts of the body) also increase during allergica rxns. and parasitic worm (helminths) infections; stain with acidic dyes
3. Neutrophils (60-70%) - phagocytic cells capable of diapedisis; also increase during bacterial infections and mediate inflammation; stain with a mixture of acidic and basic dyes
What are the 2 main types of agranulocytes and what do the do?
1. Lymphocytes (20-25%) - mostly involved in specific immunity (t-cells, b-cells); NK (natural killer) cells are non-specific; these cells increase in viral infection response
2. Monocytes (3-8%) - Mature into macrophages (primary phagocytic of immune system)
Name some diseases treated with interferon therapy.
1. Broad-spectrum - hopes as antiviral
2. Narrow-spectrum - Hep C and B; multiple sclerosis; chronic granulomatous disease; cancer (malignant melanoma, specific leukocytes and lymphomas - shuts down pain synthesis)
What is extracellular killing and which types of leukocytes can perform this function?
Extracellular killing is killing invaders without performing phagocytosis.
Eosinophisl, neutrophils, and NK cells
Which phagocytes are the first to arrive on the scene in the inflammation process
Macrophages and neutrophils
How can lab analysis of leukocytes give clues as to the type infection?
The lab can determine which of the 5 cell types are increased therefore being able to tell if it is a viral, bacterial or T-cell/B-cell infection
What is the role of the mononuclear phagocytic system in defense? What are some types that belong to this system?
It's role is to phagocytize invaders.
Some types of cells are:
1. Alveolar macrophages (lungs)
2. Macrophages in the sinuses and spleen
3. Marphophages in the kidneys
4. Dendritie cells in the epidermis
5. Circulating monocytes in the blood
6. Macrophages in the joints
7. Macrophages in the lymph nodes
8. Kupffer cells (liver)
9. Microglial cells (brain)
Which chemicals mediate inflammation?
Protaglandins, leukotrienes and histamine
Describe the 5 steps involved in phagocytosis
1. Chemotaxis of pihagocyte to microbes
2. Adherence
3. Ingestion of microbes by phagocytes
4. Killing of microbes by enzymes and other chemical
5. Eliminitation (exocytosis)
What pathogens are targeted by extracellular killing?
1. Eosinophils - parasitic helminths (worms)
2. Neutrophils - Gram-positive and Gram-negative bacteria
3. NK cells - virally infected cells and tumors
Describe the events involved in the inflammation process
1. A cut penetrates the epidermis barrier and bacteria invade
2. Damaged cells release protaglandins, leukotrienes and histamine
3. Prostaglandins and leukotrines make vessels more permeable. Histamine causes vasodilation, increasing blood flow to the site.
4. Macrophages and neutrophils squeeze through walls of blood vessels (diapedsis)
5. Increased permeability allows antimicrobial chemicals and clotting proteins to seep into damaged tissue but also results in swelling, pressure on nerve endings and pain
6. Blood clot forms
7. More phagocytes migrate to the site and devour bacteria
8. Accumlation of damaged tissue and leukocytes forms pus
9. Undifferentiated stem cells repair the damaged tissue. Blood clot is absorbed or falls off as a scab
How is the Classical Pathway activated?
The binding of antibodies to foreign antigens trigger activation
What is the complement system?
A short set of serum proteins designated numerically according to order of discovery. The initially act as opsonins and chemotactic factors indirectly triggering fever and inflammation. The end result is full complement activation is lysis of foreign cells.
How is the Alternate Pathway activated?
Pathogens or pathogenic products trigger activation - more specifically the binding of factors B,D and properdin to endotoxin or glycoproteins in the cell walls of bacteria or fungi
What are the results of activation of the complement cascade
1. C1 becomes an active enzyme when it binds to antibody-antigen complexes.
2. Enzyme C1 splits several molecules of C2 and C4.
3. Fragments of C2 and C4 combine to form a third enzyme that splits C3 into C3a and C3b.
4. C3b combines with the remaining fragments of C2 and C4 to form a third enzyme that cleaves C5 omtp C5a and C5b.
5. C5b combines with C6, C7, C8 and several molecules of C9 to form a membrane attack complex (MAC). A MAC drills a circular hole in the pathogens's cytoplasmic membrane, leading to hypotonic lysis of the cell. A membrance attack complex is a potent nonspecific antimicrobial weapon that can form against a wide variety of bacterial and eukaryotic pathogens.
What causes fever and how does fever participate in defense?
Pyrogens trigger hypothalamus to increase body's core temperature.
1. IL-1 causes hypothalamus to secrete prostaglandin
2. Result - muscle contractions, increased metabolic activity, constriction of blood vessels (raise body's cocre temp which causes chills due to reduced blood flow of constricted vessels)
3. Decrfease in IL-1 production - body temp returns to normal
How does fever participate in defense?
1. Enhances effects on interferons
2. Inhibits growth of some microorganisms
3. May enhance performance of phagocytes, cells of specific immunity and the process of tissue repair
Define Acute inflammation
It develops quickly and is usually beneficial.
Impt. in 2nd line of defense:
1. Dilation and increased permeability of blood vessels
2. Migration of phagocytes
3. Tissue repair
Define Chronic inflammation
Develops slowly and lasts a long time. May damage tissue.