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Pathogens and Immunity, Vaccines contain weakened or inactive parts of a…

- - - - The immune system helps to protect us against diseases caused by tiny invaders (called pathogens) such as viruses, bacteria, and parasites. cells, and tissues that all work together to destroy these invaders.
- - - - The first line of defense consist of Physical and chemical barriers
        
        Skin
        
        The skin consist 4 layers of thick cells which help keep foreign particles and pathogens.
        
        Eyes
        
        Blinking is a method to help keep the eyes moist and also help in flushing out the pathogens
        
        Lysozyme is an enzyme in the eye which kills pathogens
        
        Digestive System
        
        Has acid which helps to neutralize the Pathogen and also Vomiting and Diarrhea help flush out the Pathogen
        
        Respiratory system
        
        Celia are hair like structures which catch Foreign Particles which is expelled by a cough.
        
        Mucus swallows the pathogen and killing it
    - - The second line of defense is nonspecific resistance that destroys invaders in a generalized way without targeting specific particles
        
        Phagocytes
        
        All the cells in the Second Line of Defense are Phagocytes
        
        Process of Phagocytosis
        
        Phagocytes recognize pathogen and encloses it in itself
        
        Phagocytes release the digestive enzymes present in it sac
        
        Phagocytes reach site of infection
        
        Destroy the pathogen
        
        Absorb the destroyed pathogen for its own metabolism
        
        Examples of Phagocytes
        
        Macrophages
        
        derived from monocytes
        
        that can leave the circulatory system by
        moving across the walls of capillary vessels
        
        Release special proteins called as cytokines in order to
        signal and recruit other cells to an area with pathogens
        
        Dendritic cells
        
        derived from monocytes
        
        present on sites that can contact external environments
        
        act as bridge between the innate immune system and the adaptive immune system
        
        Granulocytes
        
        Type of white blood cell
        
        Contains granules (small particles) with enzymes that are
        released during infections, allergic reactions, and asthma
        
        enzymes in the granules damage or digest pathogens and release inflammatory mediators into the bloodstream
      - Functions of Second Line of Immunity
        
        Phagocytosis
        
        Inflammation (swelling)
        
        Degranulation
      - Inflamation
        
        Inflammation is a process by which your body's white blood cells and the things they make protect you from infection from outside invaders, such as bacteria and viruses.
        
        What happens when an inflammation occurs?
        
        Process of Inflammation
        
        When tissue damage occurs, macrophages
        release a chemical called cytokines
        
        Cytokines causes local vasodilation (widening of blood vessels) and increases capillary permeability (ability of solids and liquids to pass through) to improve the recruitment of leukocytes (white blood cells) to the region
        
        3.Damaged cells also release chemotactic factors (chemicals that attract other molecules/cells) which attract leukocytes to the site of infection. Phagocytosis takes place.
        
        While inflammation is necessary to allow immune cells access to damaged tissue, there are unavoidable side effects
        
        Degranulation -performed by neutrophils
        Release toxic granules to destroy the pathogen
    - - This line of defence is also known as the adaptive system as it adapts after an attack by the Pathogens
        
        Most antigens are proteins that serve as the stimulus to produce an immune response.
        
        Here are the steps in an immune response:
        
        When an antigen is detected by a macrophage (as describe above under phagocytosis), this causes the T-cells to become activated.
        
        The activation of T-cells by a specific antigen
        is called cell-mediated immunity.
        The body contains millions of different T-cells,
        each able to respond to one specific antigen.
        
        The T-cells secrete interleukin 2.
        Interleukin 2 causes the
        proliferation of certain cytotoxic T cells and B cells.
        
        From here, the immune
        response follows 2 paths: one path uses
        cytotoxic T cells and the other uses B cells.
        
        Vaccines
      - This line of defense has specialized cells which can detect only pathogens and kill them
      - Specialized cells
        
        T-cells
        
        The T cells are capable of recognizing antigens on the surface of infected body cells.
        
        The T cells bind to the infected cells and secrete cytotoxins that induce
        cell suicide in the infected cell and cause holes in the infected cells.
        
        Both of these mechanisms destroys he pathogen in the infected body cell.
        
        Helper T cells
        
        These cells secrete a certain enzyme which stimulates cell division of T cells and B cells. In other words, these cells recruit even more cells to help fight the pathogens
        
        Memory T cells
        
        These cells remain dormant after the initial exposure to an antigen. If the same antigen presents itself again, even if it is years later, the memory cells are stimulated to convert themselves into T cells and help fight the pathogen.
      - Antibodies
        
        Antibodies ) are Y-shaped proteins that circulate through the bloodstream and bind to specific antigens, thereby attacking pathogens.
        
        The antibodies are transported through the blood
        and the lymph to the pathogen invasion site.
        
        The body contains millions of different B cells, each able to respond to one specific antigen.
        
        There are 4 classes of antibodies (listed from most common to least common):
- - - - Airborne
        
        An airborne disorder is any disease that is caused by a microorganism that is transmitted through the air. There are many airborne diseases that are of clinical importance and include bacteria, viruses, and fungi.
      - Foodborne
        
        Foodborne illness is caused by consuming contaminated foods or beverages. Many different disease-causing microbes or pathogens can contaminate foods, so there are many different types of foodborne illnesses. Most foodborne diseases are infections caused by a variety of bacteria, viruses, and parasites.
      - Person to person
        
        Infectious diseases commonly spread through the direct transfer of bacteria, viruses or other germs from one person to another. This can happen when an individual with the bacterium or virus touches, or coughs or sneezes on someone who isn't infected.