Immune System: Overview PDF

Introduction to Immune System **Immunity **is the body\'s ability to resist antigens that damage tissues and organs. An individual\'s immunity is affected by: - Health - Opportunistic infections - Age - Heredity Antigens Antigens are molecules that trigger an immune response. They ca...

Introduction to Immune System **Immunity **is the body\'s ability to resist antigens that damage tissues and organs. An individual\'s immunity is affected by: - Health - Opportunistic infections - Age - Heredity Antigens Antigens are molecules that trigger an immune response. They can be found on or in: - Pathogen - Organisms such as bacteria, viruses, fungi, or parasites that causes disease, among them, Ebola, Salmonella, Shigella, Mycobacterium TB, and so on. - Toxins (poisons) - Tumour cells Definitions - **Antigen**: a molecule that triggers an immune response. - **Antibody (immunoglobulin)**: a protein that attaches to a specific antigen to identify and block its effect. - **Pathogen**: an organism that causes disease. Non-Specific (Innate) Defenses These are defenses that you are born with, and they tend to be fast-acting. They can be referred to as natural immunity, but do not confuse this term with naturally acquired immunity. Rather, let\'s use the term **innate** instead. These are not specific to a particular antigen. - Intact skin - Mucus and cilia - Digestive acids and enzymes - Coughing, sneezing - Inflammation - Phagocytosis performed by certain types of white blood cells These defenses protect us in many ways. For example, neutrophils will migrate to the site of bacteria or infection and ingest the bacteria. Moncytes or macrophages will then move in to clear the dead cells and debris as the infection subsides. Specific (Acquired Or Adaptive) Immunity These are specific to a particular antigen, have a \"memory\" of exposure, and can react more quickly when exposed to a familiar antigen Specialized Cells Lymphocytes are produced in the bone marrow and mature in the lymphatic tissues into different types. Fullscreen Illustration of three types of lymphocytes: T-lymphocytes, B-lymphocytes, and NK (Natural Killer) lymphocytes. T-lymphocytes are shown in blue, participate in the processes of cellular immunity. B-lymphocytes are shown in purple, participate in humoral immunity. NK-lymphocytes are shown in green and are responsible for natural cytotoxicity against cancer cells and virus-infected cells. - **B Lymphocytes** produce and secrete specific antibodies. They transform into - **Plasma cells**: Produce antibodies when confronted with the antigen they are coded to recognize - **Memory cells**: Can quickly reactivate the immune responses if they detect the antigen in the future - **T Lymphocytes** mature in the thymus and are involved in fighting viruses and cancer cells - **Helper T cells** promote the response of other lymphocytes - **Cytotoxic or Killer T cells** attach to antigens and kill the organism - **Suppressor T cells** stop the immune response when the antigen has been destroyed - A **Complements** is a group of proteins that help antibodies and T cell kill their targets Acquired (adaptive) immunity can be either active or passive. Antibodies are produced by the individual in response to exposure to a particular antigen (long-term immunity) The means by which immunity is acquired can be either natural or artificial. - **Natural** occurs through natural processes - **Artificial** occurs when antibodies are introduced or stimulated by artificial means - Natural - **Natural Active Immunity** occurs when antibodies are created by the host after being naturally exposed to an antigen. For example, this happens when a person gets infected with chickenpox and develops immunity as a result. - **Natural Passive Immunity** is when antibodies are passed from the mother to her baby through the placenta and breast milk. Although the baby\'s immune system is functioning at birth, it is still immature, so it relies on antibodies from the mother for up to one year. - Artificial - **Artificial Active Immunity** involves the production of antibodies after artificial exposure to an antigen, such as through vaccinations like Varivax or MMRV. - **Artificial Passive Immunity** occurs when antibodies are directly administered from a donor host through an injection. An example of this is the RhoGAM injection, which provides immunity without the host actively producing antibodies. +-----------------------------------+-----------------------------------+ | - **Combining Form** | **Meaning** | +===================================+===================================+ | Path/o | Disease | +-----------------------------------+-----------------------------------+ | Phag/o | Eating; swallowing | +-----------------------------------+-----------------------------------+ | Cyt/o; -cyte | Cell | +-----------------------------------+-----------------------------------+ | Lymph/o | Lymph | +-----------------------------------+-----------------------------------+ | Immun/o | Immune; safe | +-----------------------------------+-----------------------------------+ | Aut/o | Self | +-----------------------------------+-----------------------------------+ | **Prefix** | **Meaning** | +-----------------------------------+-----------------------------------+ | Anti- | Against | +-----------------------------------+-----------------------------------+ **Suffix** **Meaning** ------------ ------------------------- -sis State of; condition -gen Substance that produces -globulin Protein