Lymphatic System (pg 338) Vessels that transport lymph through low pressure contractions and valves  Lymph= plasma like fluid that carries important chemical messages, blood cells and nutrients Main organs  Bone marrow- specialized blood cells made here  Spleen – blood reservoir  Thymus gland- release of T cells for immune response

Immune System (pg ) Defense against foreign particles in air, water and food as well as abnormal body cells that turn into cancer Three lines of defense.  First two considered nonspecific immune responses, meaning that they do not distinguish one microbe from another.  Third is the immune system—a specific immune response that reacts in specialized ways to various invaders. All the cells involved in the immune system develop from the bone marrow.

First Line of Defense Largely physical- skin and mucous membranes defend against viral and bacterial invaders.  Intact skin provides protective barrier and has chemical defenses in the form of acidic secretions  Lysozyme, an antimicrobial enzyme secreted in human tears, saliva, mucous secretions, and perspiration, destroys the cell walls of bacteria, killing them.  Cilia and mucus in respiratory tract, trap and filter invading pathogens  Corrosive acids in the stomach and protein- digesting enzymes in digestive system destroy most of microbes carried with food.

Second Line of Defence mobilized if the invader takes up residence within the body Leukocytes, or white blood cells, may engulf invading microbes or produce antibodies.  phagocytosis,  When foreign particle penetrates skin, it is engulfed and destroyed within a macrophage.  Neutrophils attracted to damaged cells, engulf microbe and digest both. The remaining fragments of protein, dead white blood cells, and the digested invader are called pus.  Inflammatory response  Fever

Third Line of Defence Immune response  is a specific response that reacts in specialized ways to various invaders.  All the cells involved in immune system develop from the bone marrow.

Antigens  All cells have special markers located on their cell membranes. Immune system does not react to the body’s own markers but will if there is one introduced into body they don’t recognize body cellinvading cell

Antibodies Intruding cells or foreign proteins activate the production of antibodies. Antibodies  Y-shaped proteins  Specific; this means that an antibody produced against the influenza virus, for example, is not effective against HIV, the virus that causes acquired immunodeficiency syndrome (AIDS).  Attach to invading viruses, preventing binding to cells

Components of the Immune Response White Blood Cells (leukocytes) involved in the immune response Macrophage  white blood cell found in lymph nodes, bone marrow, spleen and liver  Engulfs and destroys invading pathogen or microbes Lymphocytes  white blood cells produced in bone marrow and stored in thymus gland 1. T Cells  Seek out intruder and signal its attack  Recognizes antigens located on membrane  Passes info to B cell  Specialize T Cells  Killer T Cells  Kills invading pathogen by binding with infected cells and puncturing membrane therefore it can reproduce  Suppressor T Cells  Communicates to T cells when to stop producing antibodies

2. B Cells  Produces antibodies on its membrane  Specialized B Cells  Memory B Cells  Generated during infection  Hold an imprint of antigen for specific invader so next time it will recognize and mobilize antibodies that body already has to fight

Body’s Immune System Response 1. Pathogen enters body & macrophages rush to surround, engulf and paralyze it 2. Antigens from pathogen protrude from macrophage 3. Helper T cells identify antigens and B cells make & release antibodies 4. Antibodies attach to pathogen antigens and destroy 5. Killer T cells carry out search & destroy mission for other invading cells 6. Memory B Cells memorize & store antibody info in case pathogen returns 7. Suppressor T Cells inhibit response and basically shut it off

Disorders of Immune System Abnormal functioning of the immune system can cause two types of problems: immunodeficiency diseases and inappropriate attacks of the immune system against nonthreatening agents. Allergies, Autoimmune diseases (e.g. MS), Organ transplant rejection,