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Non-Specific Body Defenses. Surface Membrane BarriersCells and ChemicalsInflammatory ResponseOther Non-Specific Defenses. Surface Membrane Barriers. PhysicalFirst line of defense The purpose is to protect the body by preventing entry and spread of microorganismsPathogens? any harmful or dise
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1. Body Defenses
2. Non-Specific Body Defenses Surface Membrane Barriers
Cells and Chemicals
Inflammatory Response
Other Non-Specific Defenses
3. Surface Membrane Barriers Physical
First line of defense
The purpose is to protect the body by preventing entry and spread of microorganisms
Pathogens? any harmful or disease-causing microorganisms or particles
Skin
Keratinized epidermis is a strong physical barrier
Acidic pH of skin secretions
4. Surface Membrane/Cells and Chemicals Mucous membranes
Line all body cavities open to the exterior
Digestive
Respiratory
Urinary
Reproductive
Provide both physical and chemical protection
Cells and Chemicals
Second line of defense; attacks anything that made it by the surface membrane barriers
5. Cells and Chemicals Phagocytes
Macrophages and neutrophils that act to engulf foreign particles and enclose them in vacuoles.
Digestive enzymes in these vacuoles break down particles.
Natural killer cells
Act as the blood and lymph “police”
Unique cells that can lyse and kill cancer cells and virus infected cells
They are not specific to any one cell, but can act on any target by recognizing non-self cell markers.
They attack cells and release toxic chemicals that target the cell’s membrane and nucleus.
6. Inflammatory Response Inflammatory Response
Cardinal Signs
Redness
Heat
Swelling
Pain
Steps
Chemical alarm
Injured cells release inflammatory chemicals (histamine and kinins)
7. Inflammatory Response (Con’t)
Cause blood vessels to dilate and capillaries to become leaky
Activate pain receptors
Attract phagocytes to the injured area
Increased blood flow to area as a result of vasodilation
The area swells (local edema) due to leaking of plasma from blood vessels
Accomplishments
8. Inflammatory Response (Con’t) Prevents the spread of damaging agents to nearby tissues
Disposes of cell debris and pathogens
Sets the stage for repair
9. Figure: 12.2
10. Other Non-Specific Defenses Other
Complement
Refers to a group of 20 plasma proteins that circulate in the blood in the inactive state
Compliment fixation? when complement becomes attached, or fixed to foreign cells.
Causes lesions in foreign cells’ membranes
Amplifies inflammatory response
11. Other Non-Specific Interferon
Chemical secreted by virus-infected cells that acts to protect nearby cells from viral infection
Act by binding to cell membrane receptors
Fever
Abnormally high body temperature
Systemic response to invasion by microorganisms
White blood cells and macrophages that have been exposed to pathogens can secrete chemicals called pyrogens that act to raise body temperature
Fever helps to increase cell metabolism and make it difficult for pathogens to reproduce
12. Specific Body Defenses Immune Response
Antigens
Cells of the Immune System
Humoral Immune Response
Antibody Function
Cellular Immune Response
13. Immune Response Immune response
Third line of defense
Immune system cells recognize foreign molecules
Cells act to inactivate or destroy them
Three characteristics
It is antigen specific? it recognizes and acts against particular pathogens or foreign substances
It is systemic
It has memory? recognizes previously encountered pathogens and mounts a quicker and stronger attack
14. Immune Response (Con’t) Two separate but overlapping arms
Humoral immunity? B cells make antibodies against specific antigens
Cellular immunity? T cells directly attack foreign invaders
15. Antigens Antigens
Antigens vs. pathogens
An antigen is any substance capable of exciting an immune system response
An immune system response activates the immune system cells (B and T lymphocytes)
A pathogen is any potentially harmful foreign invader.
A pathogen can be an antigen, but does not have to be.
16. Antigens (Con’t) Non-self antigens
Any organic substance that is recognized by the immune system cells as not being part of the body are considered non-self antigens.
Most are large molecules such as all foreign proteins, nucleic acids, many carbohydrates and some lipids.
Self-antigens
Your own cells also contain surface markers
These are mostly protein or carbohydrate markers on the cell membranes of all of your cells.
17. Cells of the Immune System An overview of immune cells
Lymphocytes
White blood cells that originate in red bone marrow
Some immature lymphocytes are released from the bone marrow and travel to the thymus become immunocompetent (differentiate into T cells)
B cells develop immunocompetence in the bone marrow, and fully develops when an antigen binds to its surface receptors
18. Cells (Con’t) Macrophages
Cells that arise from monocytes formed in the bone marrow
They act to engulf antigens and then present the non-self marker on its own cell membrane- like an antigen presenter
These cells are then recognized by the T cells
There is continual communication between the macrophages and lymphocytes
19. Humoral Immune Response Humoral Immunity
Steps of humoral immune response
Immature B cells are activated by an antigen binding to its surface receptors.
The binding event ‘sensitizes’ the lymphocyte to go into rapid division or clonal selection. Helper T cells manage this event by sending chemical messages to the B cells.
All clones have the same antigen receptor as the original.
Most B cell clones then divide to become plasma cells.
Plasma cells release antibodies at a rate of 2000/sec
20. Humoral Response (Con’t) Antibodies travel through the blood and bind to receptors on the specific antigen.
Antibody action disrupts the antigen function.
This continues for about 4-5 at the onset of the immune response, and then the plasma cells start to die out.
B cells that do not become plasma cells remain as memory cells in the blood for future invasions of this specific antigen.
21. Antibody Function Antibody Function
Compliment Fixation
Main way for antibodies to act against cellular antigens such as bacteria and or mismatched RBC.
Complement binds with antibodies attached to cellular targets.
This causes cell lysis.
Neutralization
Occurs when antibodies bind to specific sites on bacteria cells that secrete toxins.
Antibodies bind to areas where chemicals are secreted thereby blocking the action of the antigen
22. Antibody Function (Con’t) Agglutination
Occurs when antibodies bind to more than one antigen.
Multiple antigens in one antibody causes clumping of the foreign cells, or agglutination.
Precipitation
Occurs when the cross-linking process of agglutination involves soluble antigens.
The clumping causes the antigen-antibody complex to precipitate out of solution.
23. Figure: 12.8
24. Cellular Immunity Cellular Immune Response
Steps
Helper T cells are activated to form clones by having the antigen “presented” to them by a macrophage.
Helper T cells must recognize both the self and non-self antigens to be activated and this leads to cloning of the T cells.
The activated Helper T cells secrete lymphokines which stimulate the proliferation of and activity of other helper T cells and activates Killer T cells and B cells.
25. Cellular Immunity (Con’t) Killer T cells directly kill virus-infected, cancer, or foreign graft cells by binding to the cells and then secreting a toxin (perforin) which destroys their cell membrane.
Some of the T cells hang around after the infection to act as memory cells.
26. Figure: 12.9