The Immune System “The security force”

Crash course overview- Immunity https://www.youtube.com/watch?v=GIJK3dwCWCw

Organization of the Immune System Non-Specific Provides same general defense against anything not self Present from birth Specific Immunity Recognizes specific threats and mounts targeted attacks Creates a long term memory

Non-Specific Immunity Species Resistance A biological basis - keeps humans from getting sick from plant or other animal diseases.

Non-Specific Immunity First Line of Defense Mechanical and Chemical Barriers The skin is often called the first line of defense. Mucus, sebum and enzymes will catch or destroy pathogens

Non-Specific Immunity Second Line of Defense The Inflammatory Response Tissue damage causes the release of chemotactic factors such as histamines, kinins and prostaglandins that attract WBCs. This response causes redness, swelling and pain because of increased blood flow.

The Inflammatory Response

Non-Specific Immunity Phagocytosis Phagocytes are WBCs that ingest non-self substances. Neutrophils are the most common phagocytes. Monocytes (macrophages) are giant phagocytes. Phagocytes accumulate as pus at site of infection.

Macrophages have different names based on where they are found. Phagocytosis Macrophages have different names based on where they are found.

Non-Specific Immunity Natural Killer (NK) Cells They ingest tumor cells and cells infected by viruses. They do not need to be activated by a specific antigen.

Non-Specific Immunity Interferon Cells infected by viruses release the protein interferon. Interferon prevents viruses from multiplying in cells and is used in treating cancers.

Non-Specific Immunity Complement 20 inactive enzymes are activated in a series to cause the lysis of a foreign cell.

Specific Immunity Third Line of defense Two types of WBCs that arise from hematopoitic stem cells are involved in specific immunity B lymphocytes and T lymphocytes

actions are referred to as antibody-mediated immunity Specific Immunity B Cells Create antibodies antibodies bind to and clog up cells and viruses leaving them for phagocytes to attack actions are referred to as antibody-mediated immunity

Actions are considered cell-mediated immunity Specific Immunity T cells Mature in the thymus Attack cells directly Actions are considered cell-mediated immunity

Lymphocyte Circulation Most B and T cells are found in the thymus, spleen, lymph nodes, and bone marrow. Lymphocytes leave tissue through lymphatic vessels and are eventually returned to the blood via the right and thoracic lymphatic ducts

Specific Immunity Antigens are markers on the outside of foreign cells that induce an immune response with their epitope markers. Antibodies are plasma proteins called immunoglobulins that have two small regions called combining sites. Epitopes of anitgens fit into specific antibody combining sites to form an antibody-antigen complex

Crash course – humoral response https://www.youtube.com/watch?v=2DFN4IBZ3rI

Antibody-mediated Immunity Stem Cells Shortly before and after birth develop into Inactive B cells They migrate to spleen, liver and lymph nodes. Binding of antigen to antibody changes them into Active B cells Divide rapidly forming clones Plasma cells Memory Cells Stored in lymph nodes Secrete into blood Antibodies YYYYYYY

Antibodies Immunoglobulins are Y-shaped proteins They have two heavy and two light polypeptide chains Variable regions at the end of each arm allow for specific antigen binding. Chains are bound together by disulfide bonds Each has two complement binding site

Antibody Functions By binding chemical toxins they can convert them to harmless substances They can cause agglutination of antigens on the surface of microorganisms making it easier for phagocytic cells to digest them Binding to antigens can cause a change in antibody structure exposing the complement binding site initiating complement enzyme reactions which destroy the cell Complement binding site

Antibody Functions

Complement Action

Classes of Antibodies (Immunoglobins) Immunoglobulins M, G, A, E and D IgG- most abundant, produced by secondary immune response, confers passive immunity to infants from mother IgM- produced after initial contact with antigen in primary response IgA- found in mucus, saliva and tears. IgE- associated with allergies, can be harmful IgD- present in small amounts, exact function unknown.

Classes of Antibodies (Immunoglobins)

Cell-Mediated Immunity T cells mature in thymus into thymocytes Contain antigen binding sites on their surface Once activated they become either cytotoxic (killer T cells), helper T cells, suppressor T cells or T memory cells Sensitized T cells release chemotatic factors that attract macrophages to the site of infection Helper T cells help with B cell secrete antibodies Suppressor T cells help turn off B cells

Cell-mediated Immunity Stem Cells Shortly before and after birth develop into T cells They migrate to thymus, spleen, liver and lymph nodes. Binding of antigen to antibody changes them into Sensitized T cells Cytotoxic T cells Suppressor T cells Helper T cells Memory T cells Seek out cells with specific antigens and destroy them, release chemotatic factors increasing phagocytosis Prevent B cells from converting into plasma cells Help B cells convert to plasma cells to create more antibodies Antibody producing cells

Immunization

Passive and Active Immunity Natural Immunity Exposure to agent is not deliberate Passive Immunity Fetus receives protection through placenta Infant receives protection from breast milk Injection of antibodies that were created by another individual’s immune system Artificial Immunity Exposure to agent is deliberate Active Immunity Child develops measles and has protection from further infections Injection of agent such as a vaccine

Disorders of the Immune System Allergies Autoimmune Disease Acquired Immunodeficiency Syndrome

Allergies Hypersensitivity to usually harmless substances Allergens are substances that cause allergic responses IgE plays main role in allergic response Usual symptoms, are runny nose, conjunctivitis, hives Anaphylactic shock can result in severe responses and can lead to death if untreated Antihistamines normally relieve symptoms but adrenaline may be needed in severe cases

Autoimmune Disorders Inappropriate or excessive response to self-antigens. 3 out of 4 cases affect women IgG antibodies are made against self DNA Examples Systemic Lupus Multiple sclerosis Diabetes mellitus Grave’s disease Myasthenia gravis Treatment usually focuses on relieving symptoms

Acquired Immune Deficiency Syndrome Caused by the HIV virus, a retrovirus Virus attacks T lymphocytes and immune system is destroyed Persons are susceptible to unusual forms of cancers and infections that can lead to death A “cocktail” of antiviral are currently used to keep the infection from developing into AIDS