how does the body identify and destroy pathogens?
TRANSCRIPT
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How does the body identify and destroy pathogens?
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a microorganism such as a virus, bacterium, prion, or fungus, that causes disease in a plant or animal
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Infectious Protein◦ No DNA or RNA◦ NOT LIVING
AKA spongiform (like a sponge) encephalopathies (pathogen of the brain)
Mad Cow Disease - Cows Scrapie - sheep Kuru – humans New Guinea,
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Has two components◦ Protein covering◦ Nucleic acid (either RNA OR DNA, rarely both)
inside
◦ Infect and “take over” the cell’s replication machinery
◦ Colds, Influenza, HIV
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Living prokaryote!
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Barriers◦ Separate the organism from its environment
Nonspecific immune response – second l◦ Inflammatory Response◦ Repel and destroy foreign “cells”
Specific immunity◦ How lymphocytes identify and remember certain
types of invasive bacteria, viruses, toxins.◦ Create a “rapid defense system” for any second
attack
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Skin Mucous membranes
◦ Secrete mucus (all “openings” to the environment)◦ Mucus contains lysozyme (kills bacteria)
Others◦ Cilia (Resp. system)◦ Stomach acid (low pH kills bacteria)◦ Enzymes (lysozyme in tears)◦ Respiratory tract
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◦ Inflammatory Response
◦ Histamine triggers the response Increases the permeability of capillary membranes
(lets white blood cells out of the capillaries)
◦ Phagocytes/macrophages – ingest invaders
◦ Natural Killer cells – lymphocytes that provide a rapid
◦ response to a viral infection.
◦ Help contain a viral infection ◦ while antibodies are being made.
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Increased blood flow RESULT: Redness, swelling, pain, warmth,
◦ Clotting (if blood vessel damaged)
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Match these to the conditions (next page)
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Effects of inflammation Pain Heat Swelling Redness Loss of function (sometimes)
Chronic (long term) inflammation (depending on location
Periodontitis (gums)Atherosclerosis (blood vessels)Crohn’s disease (intestines)Hayfever (respiratory system)Arthritis(joints)
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Increase body metabolism , speeding up the repair process (only up to 104 F)
Slow down the reproduction of some bacteria and viruses .
Makes YOU slow down and “rest”
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(1) Fever slow down some bacteria and viruses.
(2) Fever increase metabolism (enzymes work faster up to 104 F)
(3) fever makes a patient feel ill, condition which makes the patient more likely to rest.
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Complement proteins ◦ Stimulate inflammation and
phagocytosis
Interferon ◦ Send warning signals to neighboring cells◦ Released by a cell which was attacked by a virus
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Programmed cell death (apoptosis)
Based on lack of presence of pathogen (foreign antigens)
Signal sent to “self destruct”.
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Cells and Tissues that learn about and learn to recognize and attack foreign substances (based on antigen recognition)
Include◦Macrophages(from general response)◦T-cells◦B cells
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Cell mediated immune response◦ Macrophages/phagocytes
– engulf (eat) foreign invaders
◦ T cells - identify and destroy infected cells;
communicate with B cells
Humoral Immune response◦ B cells
– produce antibodies, immune memory
◦ Antibodies – specific proteins design to restrict spread of pathogen
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When macrophage “eats” the bacteria it “displays” antigens
Helper T binds to antigens
Result: chemical message released◦ more Helper T made◦Killer T activated◦ Communicate with B cells
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Antibodies ◦Bind to a surface antigen on bacteria and clumps them together so that macrophage can “eat them”
◦Complement proteins Put holes in bacterial cells
◦Can inactivate or destroy toxins
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Antibodies bind to antigens
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Chemical messages decrease B and T cells
IMMUNE MEMORY
◦Memory B cells are formed Future rapid response cells Circulate in blood
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Memory T Cell
Suppressor T Cell
Memory B Cell
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The next time that an individual encounters that same antigen, the immune system is ready to destroy it quickly.
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MEMORY CELLS◦ Long term protection against re-infection for life
How?◦ Memory B cells remain in the blood. (Bone
marrow can remake as needed)◦ Recognize antigen (second time response)
Rapid and large production of specific antibodies
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Short –term immunity◦ Some vaccines or fluids containing antibodies◦ Infants have antibodies from mother
Due to blood exchange during pregnancy Due to mother nursing child
Long-term immunity ◦ Stimulated by infection
◦ Can be obtained through vaccines made from infectious agents that are not infectious, but do cause antibodies to form
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Long term immunity◦ Body has been exposed to infective agent
Disease or vaccine
Short term immunity◦ Individual given antibodies (but the body has not
learned how to make more)
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Create a table with three columns and four rows
In the first column
Vaccine Antibiotic Antiviral
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Column 1 – When are they used (before or during or after infection?)
Column 2 – What are they effective against?
Column 3 - Do they treat, prevent, or cure?
Column 4 Do you have other questions or comments to add?
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Virus consumed by a macrophage
2. Macrophage displays the virus antigens
3. Helper T-Cell recognizes “enemy” . Call in the troops.
4. B cells and Killer T Cells are manufactured
5. B cells produce antibodies that bind the virus. Killer T Cells destroy infected body cells.
6. Suppressor T cells stop production of defense.
7. Memory cells remain for future rapid response.