ImmunoDefense System PDF

Anatomy and Physiology 2 Review Sheet Kimberly Denise Vigee’ N.D. ImmunoDefense System - Functions of the immune system: 1. provide a barrier to prevent invaders (bacteria, viruses, parasites, chemicals, etc.) from infection or inflammation 2. detect and e...

Anatomy and Physiology 2 Review Sheet Kimberly Denise Vigee’ N.D. ImmunoDefense System - Functions of the immune system: 1. provide a barrier to prevent invaders (bacteria, viruses, parasites, chemicals, etc.) from infection or inflammation 2. detect and eliminate the invaders before they replicate 3. eliminate invaders whether they have replicated or not - Resistance – the body’s ability to inactivate pathogens, etc. - 2 Types of Defense Resistance: Nonspecific Resistance and Specific Resistance Nonspecific Defense Resistance - directed against all pathogens and foreign substances regardless of their nature - 6 Major Nonspecific Defense Mechanisms: Barriers, Chemicals, Phagocytosis, Immune Surveillance, Inflammation and Fever 1. Barriers – considered the first line of defense. They prevent the approach and penetration of a harmful agent. Should the harmful agent pass through the barriers then the second 1st line of defense (chemicals) is activated. Line of Barriers Include: Defen 1. Skin – largest organ of the body se - tightly packed cells filled with keratin (dead cell layer) make it very difficult for pathogens to penetrate. - secrete antibacterial substances, i.e. immunoglobulins 2. Microorganisms that grow on the surface of the skin also provide a barrier b/c now the microorganism and pathogen must compete for nutrition and space. 3. Mucous Membranes – found in the respiratory and digestive tracts - Have the ability to trap the foreign particles before they can penetrate. - The respiratory tract also has an added advantage: cilia which helps to expel the foreign particle after the mucus traps it. 4. Fluids (tears, saliva, urine) –flush out the pathogens before they invade a tissue Kinds of Fluids that inhibit bacteria: Anatomy and Physiology 2 Review Sheet Kimberly Denise Vigee’ N.D. 1. Lysozymes – found in tears, saliva and nasal passages 2. Sebaceous Secretions and Salts – found in perspiration—that antibacterial substance we talked about previously produced in the skin 3. Hydrochloric Acid – found in the stomach 2. Chemicals (“Complement” and Interferon) - considered the second line of defense. A. Complement – a group of serum proteins normally found in blood - Macrophages (WBC found in blood) are responsible for making complement - These proteins are in their inactive form - Complement proteins become activated when they come in contact with any foreign substance (is not antigen specific) - They work with (complement) antibodies so they are considered part of humoral immunity (antibody immunity) - Complement is a chemical defense that promotes: 1. phagocytosis 2. inflammation 3. lyzing of cells B. Interferon – a protein secreted when a virus is present - Interferon functions include: 1. inhibiting viral replication within host cells 2. activating natural killer cells and macrophages 3. increases the resistance of host cells to viral infection - Steps to Provide Viral Protection: 1. When a cell becomes infected with a virus, the cellular functions usually stop and the virus replicates. 2. When the cell is full of viruses, it ruptures and releases its viruses to infect neighboring cells. 3. When a virus infects a cell, that cell produces interferon, which diffuses into neighboring uninfected cells. 4. Interferon stimulates the uninfected cells to produce a protein that blocks viral replication. 5. Interferon does not protect the cell in which it was made but it does protect neighboring cells. Anatomy and Physiology 2 Review Sheet Kimberly Denise Vigee’ N.D. 3. Phagocytosis – cell eating * Phagocytes– primarily the 2 leukocytes: neutrophils and macrophages 1. Neutrophils - are granular (membrane bound enzymes) leukocytes - are the most common of the types of leukocytes - are attracted to the following: 1. bacteria – they perform chemotaxis and phagocytosis on bacteria 2. foreign material - they perform chemotaxis and phagocytosis on foreign material 3. inflammation – accumulate fluid i.e. pus Note: Be aware that inflammation is not always a bad thing – the goal of the immune system is to add nutrient containing fluid to the infected site and heal the tissue. - Are usually the first cells to leave the blood and migrate to the site of an infection where they phagocytize bacteria. - Neutrophils usually die (life span is usually shorter than one day) after phagocytizing several bacteria = Suicide Mission - Pus = an accumulation of dead neutrophils, cellular debris, and bacteria. - Acute infection - with this situation, one would see an increase in neutrophils 2. Macrophages – they are agranular leukocytes. - When monocytes leave the blood, they become macrophages by increasing in size and developing additional lysosomes. - Macrophages usually appear at the scene of an infection after the neutrophils and are responsible for clearing away cellular debris and dead neutrophils. - Macrophages are also present in uninfected tissues where they may phagocytize the invading agents before there is tissue damage. i.e. present in lymph nodes where they cleanse the lymph as it filters through the node, also it provides a similar cleansing action on the blood as it passes through the liver and spleen. 4. Immune Surveillance - - Performed by natural killer cells Anatomy and Physiology 2 Review Sheet Kimberly Denise Vigee’ N.D. - detect abnormal cells i.e. cancer, etc. due to a change in the cell’s surface - release a substance that lyses cells 5. Inflammation - - Symptoms of inflammation - redness, warmth, swelling, pain - Responses to inflammation: 1. increase in blood flow (vasodilation) 2. increased activation of phagocytosis (macrophages and neutrophils) 3. increase in capillary permeablility of a vessel draining area 4. increase in complement release 5. increase in clotting reactions 6. increase in local temperature of the area 6. Fever - increased body temperature above 98.6 degrees F. - Fever is caused by pyrogens (a fever producing substance outside the body) - Examples of pyrogens: viruses, bacteria, fungi, drugs and toxins - Pyrogens tell the hypothalamus to increase body temperature to: 1. inhibit the pathogen 2. increase speed of metabolism and healing - When to call the doctor: 1. if fever is above 104 degrees F 2. if fever lasts more than 7 days 3. if symptoms get worse Specific Defense Resistance - Humoral or Cellular Immunity 3rd Line - Specific Defenses are either: of Defense 1. Innate Immunity – present at birth Examples include: skin resistance (i.e. keratin), stomach acid (hydrochloric acid) 2. Acquired Immunity – develops with exposure to specific agents or toxins Acquired Immunity can be divided into natural or artificial immunity: Anatomy and Physiology 2 Review Sheet Kimberly Denise Vigee’ N.D. 1. Acquired Natural Passive Immunity – conveyed to fetus from mother a. IgG – passes via the placenta b. IgA – passes via the breast milk 2. Acquired Natural Active Immunity – infections that produce an immune response and leads to immunological memory 3. Acquired Artificial Passive Immunity – antibody transfer or antibiotics via IV or intramuscular injections 4. Acquired Artificial Active Immunity – immunization or vaccines - 2 Characteristics of specific defense resistance: 1. Specificity – defense mechanisms are programmed to be selective 2. Memory – Once the system has been exposed to a particular invading agent, components of the specific defense resistance remembers that agent and launches a quicker attack if the antigen enters the body again. - Cell Mediated Immunity vs. Antibody-Mediated Immunity (Humoral Immunity) 1. Cell Mediated Immunity --- T Cells * When an antigen presents itself to the body, T-cells secrete chemicals that result in a cloning of more T-Cells. * What is an antigen – any substance that results in the production of antibodies. Examples include: bacteria, viruses, toxins, etc. * There are 4 subgroups in cloning: 1. Killer T-cells – directly destroy the cells with the offending antigen 2. Helper T-cells – secrete substances that stimulate B-cells and T-cells 3. Suppressor T-cells – inhibit B-cells and T-cells; opposite of Helper T- cells 4. Memory T-cells – remembers the specific antigen and stimulate a faster and more intense response if the same antigen is reintroduced to the body. * Why get vaccinated? It stimulates the memory cells to remember what action was needed to destroy the antigen. Anatomy and Physiology 2 Review Sheet Kimberly Denise Vigee’ N.D. 2. Antibody-Mediated Immunity (Humoral Immunity) ---The result of B-cell action. * What do B-cells produce? Plasma cells! Plasma cells produce antibodies (immunoglobulins) that react with antigens. * Why are antibodies called immunoglobulins? They are part of a protein class called globulins and because they conduct an immune response. * Antibodies are found in 2 places: blood and lymph * 5 Classes of Immunoglobulins (Antibodies) 1. IgG – found in all body fluid; most common of the types, very important to fight bacterial and viral infections, only one that passes across placenta 2. IgA – found in areas that are exposed to outside foreign substances: nose and breathing passageways, digestive tract, ears, eyes, saliva, blood, tears, breastmilk 3. IgM – found in blood and lymph fluid, the first type of antibody made during infection 4. IgE – found in the lungs, skin and mucous membranes, These are high in people with allergies because they react with pollen, spores and animal dander. They cause the mast cells to release histamine, responsible for allergic reactions. 5. IgD – found in small amounts under the belly and chest, function is unclear