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Immunity lec 9 By Dr. shahad mansour Immunity (resistance): is the body's defense against infectious organisms and other invaders, through a series of steps called the immune response. The immune system: which is made up of special cells, proteins, tissues, and organs, defends people ag...

Immunity lec 9 By Dr. shahad mansour Immunity (resistance): is the body's defense against infectious organisms and other invaders, through a series of steps called the immune response. The immune system: which is made up of special cells, proteins, tissues, and organs, defends people against invaders , keeping people healthy and preventing infections. There are two types of immunity: 1-Non-specific (innate): as the name suggests, is not specific to a certain group of micro-organisms and act against every invader of the body. 2-Specific (acquired): immunity that an organism develops during lifetime result of exposure to antigens (microbes, toxin or other foreign substances). it’s the second line of defense involves production of antibodies and generation specialized lymphocytes against specific antigens.  Non-specific immunity Skin is the first barrier and the first mechanism of non-specific defense. The epithelial surfaces form a physical barrier that is impermeable to most infectious agents, acting as the first line of defense against invading organisms. presence of sebaceous glands in the dermis provides an environment unsuitable for the survival of microbes. presence of sweat glands that secrete sweat which washes infections off (High salt content of sweat dries microorganisms off). The flushing action of tears and saliva helps prevent infection of the eyes and mouth. Saliva contains anti-bacterial properties due to lysozymes. In the gastrointestinal and respiratory tract, movement due to peristalsis or cilia, respectively, helps remove infectious agents. The gut flora can prevent the colonization of pathogenic bacteria by secreting toxic substances. If micro-organisms penetrate non-specific defense systems they meet the second line of defense including phagocytic white blood cells , antimicrobial proteins and inflammatory response.  Specific immune response are found in two types: 1. Naturally acquired immunity 2. Artificially acquired immunity  There are two mechanisms for adaptive immunity 1. Humeral immunity: for which the protective function of immunization could be found in the humor (fluid or serum). - It is involve a cellular macromolecules which are found in the body’s fluids. So living cells do not act directly on the pathogen. - The immune cells indirectly attack the pathogen by making a cellular molecules which directly affect the pathogen. - There are many molecules like antibodies. Antibodies are molecules released by B cells that act directly on the target pathogen. - Humeral Immunity primarily targets extracellular pathogens like bacteria. 2. cellular immunity: for which the protective function of immunization was associated with cells. - it is an immune response that does not involve antibodies, but rather involves the activation of phagocytes, T-lymphocytes, and the release of various cytokines in response to an antigen. - Cellular immunity is working at microbes that survive inside cells. It is most effective in removing virus-infected cells, but also participates in defending against fungi, protozoans, cancers, and intracellular bacteria. It also plays a major role in transplant rejection. Immune cells