1. IMMUNITY Walter Benitez Caryn Crabb Alex Flores Annie Truong Courtney Vazquez

2.  IMMUNITY is the protection against infectious diseases, it can be gained either actively or passively  Protection against diseases are provided by the body’s defense or the IMMUNE SYSTEM DEFENSE AGAINST DISEASE

3. EXTERNAL DEFENSE SYSTEM  Humans have many mechanisms to protect ourselves against infectious diseases  When we are healthy, physical, chemical, and cellular defenses prevent pathogens from entering the body  Hydrochloric acid that is found in the stomach kills off bacteria that is ingested with many food and drinks  Blood clotting is a defense mechanism that prevents the loss of blood and prevents pathogens from entering the body through wounds in the skin

4. INTERNAL DEFENSE SYSTEM  If and when pathogens enter the body, white blood cells recognize them as foreign cells and kills them off  The foreign cells are called ANTIGENS. White blood cells are able to recognize these cells because they have distinctive large molecules that cover their surface  There are two types of white blood cells: PHAGOCYTES and LYMPHOCYTES  Some lymphocytes produce ANTIBODIES, which are protein molecules that act against specific antigens  Cell surface antigens are molecules on the surfaces of our cells that are not found in other organisms, or even humans.  Responsible for determining whether or not to produce antigens  The response of lymphocytes to the presence of a foreign antigen is known as the IMMUNE RESPONSE

5. EXAMPLE FOR INTERNAL DEFENSE SYSTEM  Cell surface antigens are used to recognize the foreign and non-foreign cells  If a transfusion of, say blood type B to blood type A, is made, then the blood type A will be recognize the type B as a NON-SELF and create antigens. If it were type B to type B, then it would recognize as SELF and not create antigens

6. CELLS OF THE IMMUNE SYSTEM  There are two groups of white blood cells in the immune system: Phagocytes and Lymphocytes

7. PHAGOCYTES  Produced throughout life in bone marrow where they remove dead cells  Types of phagocytes:  Neutrophils: short lived cells that are released in large numbers during infections  Travel throughout the body, leaving the blood squeezing through the wall of capillaries to “patrol” the tissues  These die after killing and digesting some pathogens  Macrophages: long lived cells that are larger than neutrophils  Play a crucial role in initiating immune responses, then cut up pathogens to display antigens that can be recognized by lymphocytes  Made in the bone marrow and travel in the blood MONOCYTES which become monophages once they leave the blood and settle in the organs  These are found in the liver, spleen, kidney, and lymph nodes

8. PHAGOCYTOSIS  Histamines: the chemicals released by cells when pathogens invade the body causing an infection  These attract passing neutrophils to the site. The neutrophils destroy the pathogens by phagocytosis.  The stages of phagocytosis are:  Attraction  Recognition and Attachment  Endocytosis  Bacteria with a phagocytic vacuole  Fusion of lysosomes and phagocytic vacuole  Killing and Digestion

9. LYMPHOCYTES  Plays an important role in immune response  Lymphocytes are smaller than phagocytes  Only mature lymphocytes can carry out immune responses

10. B-LYMPHOCYTES  While the B cells mature, the gene codes change in a variety of ways to code for different antibodies  they then divide into smaller identical cells called Clones  The B cell