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Lymphatic/Immune System
Grecia Lopez, Per.1 - Coggle Diagram
Lymphatic/Immune System
Grecia Lopez, Per.1
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Purpose and examples of First, Second and Third line of defense
2nd line of defense:
- Composed of phagocytes such as macrophages and neutrophils (white ingesting and digesting blood cells that protect against foreign invaders) and Natural Killer (NK) Cells.
- Create inflammatory responses.
For example: Fever
- Many have pattern recognition receptors that recognize and bind to structures on microbes to disarm them
Inflammatory Response:
- Triggered when body tissues are injured due to trauma, chemicals, or infections.
- Prevents the spread of damaging agents by disposition of cell debris and pathogens to alert the adaptive immune system and set up for repair.
- Cytokines, complements (blood born proteins that enhance immune response)
Cardinal Signs: Redness, swelling, heat, pain, and impairment of function
3rd line of defense:
- Attacks particular foreign substances
- Lymphocytes, antibodies, memory cells
- Takes longer to react
- Branches off into Humoral (B Cell) and Cellular (T Cell) Immunity
1st line of defense:
- Skin and mucous membranes (cilia) which produce protective chemicals that inhibit or destroy microorganisms.
For example: Keratin is resistant to weak acids, bacterial enzymes, and toxins.
Acid: Acidity inhibits growth; acid mantle
Enzymes: Lyozome of saliva, respiratory mucus, and lacrimial fluid that kills microorganisms
Mucin: Sticky mucus that lines the digestive and respiratory tract to trap microorganisms
- Is considered a physical barrier to most microorganisms
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Antigens and antibodies
Antigens:
- Substances that mobilize adaptive defenses and provide immune response. Usually, they are large complex molecules that are not found necessarily within the body.
- Can be a complete antigen or a hapten (incomplete antigen)
- Contain antigentic determinants recognized by the immune system
Self-Antigens:
- Cells covered with a variety of proteins located on surface that are non-antigenic to self but may be antigenic to others in transfusions
- Coded by genes of major histacompatibility compled (MHC)
- UNIQUE TO EVERY INDIVIDUAL
- Contain grooves to hold self-antigens or foreign antigens
Antigen Presenting Cells:
- Engulf antigens and present fragments of T cells for recognition
- Dendritic cells, macrophages, and B cells
Dendritic Cells (link between the adapative and innate systems): Phagotize pathogens that enter tissues to present atigens to T-cells in the lymph node Macrophages: In the lymphoid organs they present antigens to T-cells to not only activate T cells but activate macrophages and the inflammatory responseB Cells: Present antigens to Helper T Cells to assist their activation
Antibodies:
- Proteins secreted by plasma cells that can bind
- Antibodies do not destory antigens, they inactivate them and tag them for destruction.
- They tend to go after extracellular pathogens
- Form antigen-anibody (immune) complexes
Defense Mechanisms:
- Neutralization: Antibodies block SPECIFIC sites on viruses to prevent antigens from binding to receptors on tissue cells.
- Agglutination: Antigen-Antibody complexes become cross linked to clumps.
- Precipitation: Soluble molecules are cross linked into complexes to precipiate.
- Complement fixation and activation: When several antibodies are bound close together on some antigen to create bindings sites on stems that are aligned.
- IgM: First antibody secreted by plasma cells durig primary response that activates complements.
- IgA: Found in body secretions that help stop pathogens from attaching to epithelial cell surface.
- IgD: Found on B Cell surface to function as B cell antigen receptors.
- IgG: Most abundant antibody that allows for secondary and late primary responses.
- IgE: Stem and binds to most mast cells/basophils to release histamine for inflammation.
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Immunological Memory:
Primary Immune Response:
- Cell proliferation and differentitaion upon FIRST EXPOSURE to antigens
- Takes a while to kick into effect
Secondary Immune Response:
- Pre-exposure to the same antigen but gives a quicker, prolonged, effective response.
- Immunological memory responds in hours as antibody levels remain high for a long long time
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B Cells vs. T Cells
B Cells:
- Form the humoral response by secreting antibodies
- Target extra-cell pathogens
- Originate in the red bone marrow
- Effect plasma cells and have memory
- Activated when antigens bind to the surface receptors, cross linking.
- Leads to proliferation and differentiation of B Cells so that clones become plasma cells (antibody secreting effector cells) or memory cells
- Amplify responses of the humoral and cellular immune responses.
T Cells:
- Form the cellular response by targeting intracellular pathogens
- Some kill directly while others kill indirectly
- Originates in the thymus, thus effecting cytotoxic cells, Helper T cellsm and Regulatory T Cells
- Does have a memory function
- ONLY RESPOND to processed fragments of antigens displayed on surfaces of cells by major histocmpatibility complex (MHC) proteins.
- Are activated by a two step process: Antigen Binding and Co-stimulation
- CD4 cells become Helper T Cells (Th) to activate b cells, other T cells and macrophages...some even become Regulatory T cells which prevent autoimmune reactions.
- CD8 cells become Cytotoxic T Cells (Tc) that are capable of directly destroying cells that have foreign antigens with a lethal hit.
Helper, cytotoxic, and regulatory cells are ACTIVATED T cells.
Proliferation and Differentiation:
- T cells are activated, enlarged, and proliferate (multiply) in response to cytokines (chemical messengers of the immune system that mediate cell development, differentiation, and respond to interferon's and interleukin's).
- Large amounts of activated T cells can lead to inflammatory cytokines which can lead to cancer known as hpyerlasia
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