Immunity
Specific Defenses The specific defense mechanisms are concerned with selective elimination of specific micro organisms.
Specific Immune Response <ul><li>Four features characterize the immune response: specificity, the ability to respond to an...
Specific Immune Response <ul><li>There are two specific immune responses: the humoral immune response and the cellular imm...
Antigens and Antibodies <ul><li>Antibodies are proteins that protect against foreign invaders, either foreign molecules, v...
Antibody  (Immunoglobulin) <ul><li>Antibodies are produced by  B lymphocytes. </li></ul><ul><li>Antibodies are Y-shaped mo...
Antibodies <ul><li>Antibodies fit together with and bind with antigens like a lock and key. </li></ul><ul><li>The body doe...
<ul><li>Cells, particles, or molecules that are marked with antibodies, </li></ul><ul><ul><li>1. may be phagocytized (engu...
Types of immunoglobulin <ul><li>There are five immunoglobulin classes.  </li></ul><ul><li>IgM, formed first, is a membrane...
Humoral Immune Response
B - Lymphocytes <ul><li>These white blood cells attack pathogens and other foreign bodies in a different way.  </li></ul><...
Clonal Selection <ul><li>B cells that encounter the correct antigen with their antibody receptors become activated and beg...
B lymphocytes <ul><li>B lymphocytes have receptors (antibodies) attached to their surface which function to detect antigen...
Cellular Immune Response
<ul><li>This is the antibody-independent immunity provided by T cells. </li></ul><ul><li>Sensitized T cells undergo rapid ...
The complement system <ul><li>The complement system consists of a number of different proteins that help defend the body w...
Functions of the Complement System <ul><li>The activated proteins stimulate mast cells causing inflammation and attract ph...
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Immunity 2

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Immunity 2

  1. 1. Immunity
  2. 2. Specific Defenses The specific defense mechanisms are concerned with selective elimination of specific micro organisms.
  3. 3. Specific Immune Response <ul><li>Four features characterize the immune response: specificity, the ability to respond to an enormous diversity of antigens, the ability to distinguish self from non self, and memory. </li></ul><ul><li>The specific immune response is directed against antigens that evade the nonspecific defenses. </li></ul>
  4. 4. Specific Immune Response <ul><li>There are two specific immune responses: the humoral immune response and the cellular immune response. </li></ul><ul><li>The humoral immune response employs antibodies secreted by B cells to target antigens in body fluids. </li></ul><ul><li>The cellular immune response employs T cells to attack body cells that have been affected by pathogens. </li></ul>
  5. 5. Antigens and Antibodies <ul><li>Antibodies are proteins that protect against foreign invaders, either foreign molecules, viruses, or cells. They are capable of recognizing specific particles due to their shape. Their ability to recognize foreign shapes makes them useful in defending against foreign invaders. </li></ul><ul><li>Antigens are molecules that antibodies are capable of recognizing. They are usually a protein or carbohydrate chain. The body can recognize bacteria and viruses as being foreign because they have antigens on their surface which are different than the bodies &quot;self&quot; antigens. </li></ul>
  6. 6. Antibody (Immunoglobulin) <ul><li>Antibodies are produced by B lymphocytes. </li></ul><ul><li>Antibodies are Y-shaped molecules. </li></ul><ul><li>The basic unit of an antibody, or immunoglobulin, is a tetramer of four polypeptides: two identical light chains and two identical heavy chains, each consisting of a constant and a variable region. </li></ul>
  7. 7. Antibodies <ul><li>Antibodies fit together with and bind with antigens like a lock and key. </li></ul><ul><li>The body does not produce antibodies that bind to its own (self) antigens. Therefore all particles that are bound to antibodies are foreign. </li></ul>
  8. 8. <ul><li>Cells, particles, or molecules that are marked with antibodies, </li></ul><ul><ul><li>1. may be phagocytized (engulfed) by neutrophils or macrophages. </li></ul></ul><ul><ul><li>2. may agglutinate (clump together) because each antibody is capable of binding to two antigens. Antigens attached to cells will cause the cells to clump together. The clumps are then phagocytized. </li></ul></ul><ul><ul><li>3. may activate the complement system. The complement system is a system of blood proteins that enhances the elimination of foreign cells or particles. </li></ul></ul>
  9. 9. Types of immunoglobulin <ul><li>There are five immunoglobulin classes. </li></ul><ul><li>IgM, formed first, is a membrane receptor on B cells, as is IgD. </li></ul><ul><li>IgG is the most abundant antibody class and performs several defensive functions. </li></ul><ul><li>IgE takes part in inflammation and allergic reactions. </li></ul><ul><li>IgA is present in various body secretions. </li></ul>
  10. 10. Humoral Immune Response
  11. 11. B - Lymphocytes <ul><li>These white blood cells attack pathogens and other foreign bodies in a different way. </li></ul><ul><li>Each lymphocyte carries a specific type of antibody, which has a chemical 'fit' to the antigens carried by a particular type of invader. </li></ul><ul><li>When pathogens are present, the lymphocytes respond by 'trying out' a range of antibody 'shapes', until they find the right one - like a burglar using skeleton keys, trying each key in turn until one fits the lock. </li></ul><ul><li>Once the appropriate antibody is found the successful lymphocytes reproduce quickly, making millions of copies of the antibody that neutralizes the invader. </li></ul>
  12. 12. Clonal Selection <ul><li>B cells that encounter the correct antigen with their antibody receptors become activated and begin to divide many times producing plasma cells, which, in turn produce antibodies. </li></ul>
  13. 13. B lymphocytes <ul><li>B lymphocytes have receptors (antibodies) attached to their surface which function to detect antigens. </li></ul><ul><li>There is only one specific kind of receptor on the surface of a lymphocyte. </li></ul><ul><li>A single B lymphocyte can therefore detect only one kind of antigen. </li></ul><ul><li>Our bodies have millions of different kinds of B lymphocytes. </li></ul>
  14. 14. Cellular Immune Response
  15. 15. <ul><li>This is the antibody-independent immunity provided by T cells. </li></ul><ul><li>Sensitized T cells undergo rapid multiplication in response to an antigenic invasion. </li></ul><ul><li>The clone of cells, so formed, reach the infected area and bind with the antigens. </li></ul><ul><li>The cells release perforin molecules which destroy the infected cells. </li></ul>
  16. 16. The complement system <ul><li>The complement system consists of a number of different proteins that help defend the body when they are activated. </li></ul><ul><li>Each activated complement protein activates many others so that a large number of active proteins are produced. </li></ul><ul><li>The following may initially activate the complement system: </li></ul><ul><ul><li>Antigen-Antibody interaction </li></ul></ul><ul><ul><li>Substances on the capsules or cell walls of microorganisms; substances produced by microorganisms </li></ul></ul>
  17. 17. Functions of the Complement System <ul><li>The activated proteins stimulate mast cells causing inflammation and attract phagocytes (neutrophils, macrophages) to the area. </li></ul><ul><li>Complement proteins bind to microorganisms and other particles enhancing their recognition by phagocytes. </li></ul><ul><li>Other complement proteins produce holes in bacterial cell walls allowing salts and fluids to enter, rupturing the cell. </li></ul>It is called complement system because it enhances (complements) other immune responses such as the inflammatory reaction and the antibody-mediated response (the proteins bind to microbes that already have antibodies attached, improving recognition by phagocytes).

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