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Lymphatic System (Defenses (non-specific (Barriers (Skin is our first line…

- - - - Cell-mediated
      - humoral (antibody-mediated) immunity
    - - can be bacteria, viruses, fungi, asbestos, chlorine, or even the wrong blood
  - - - body temperature increases, speeds up chemical reactions in the body which helps to speed our defense mechanisms
    - - four symptoms that occur: heat, redness, pain and swelling.
      - inflammatory response consists of:
        
        Vasodilation
        
        histamine released from mast cells causes vasodilation in blood vessels and is responsible for heat and redness of inflamed tissue
        
        increased Vascular Permeability
        
        histamine released from the mast cells increases the permeability of surrounding capillaries
        
        more fluid moves into the interstitial space resulting in swelling of the tissue or edema
        
        also pushes against the nerves in the area causing pain
        
        Tissue injury
        
        injured cells release their contents which activates a mast cell (an activated basophil) to release histamine.
        
        Recruitment of Phagocytes
        
        local infection stimulates macrophages to clean up debris in the area
        
        If the infection is more severe, the neutrophils are attracted to the site in large numbers
        
        During the process of fighting, cellular remains appear as pus at the site of infection
      - one of the most important non-specific defenses once an organism breaks through the skin or mucous membrane
      - pathogens are killed and debris is removed but the increase in vascular permeability also encourages the entry of clotting factors
      - also helps to move antigen to lymph nodes by increasing capillary permeability and here a specific defense can occur if needed
    - - Skin is our first line of defense
      - constantly being sloughed off so bacteria that lands on it is also sloughed off
      - properties of the skin that help keep organisms out are the dryness of the skin and the low pH of sweat
      - acid in our stomach is also hostile to organisms
      - Saliva contains an enzyme called lysozyme which kills bacteria by destroying their cell walls
      - bacteria that belongs in our body called normal flora that helps keep other bacteria from invading
    - - "eat" foreign organisms or toxins to destroy them
      - monocytes that have moved into the tissue
      - Neutrophils can also phagocytize
    - - move through the body like sentries checking to see if there is anything out of order
      - when in contact with a foreign cell, they release their chemicals onto the cell which causes it to rupture
      - type of lymphocyte that contain granules with chemicals inside
      - phagocytes come into the area to clean up the debris.
    - - Various ways this can act:
        
        If only a few complement proteins are stimulated, they will trigger others to become active in greater numbers.
        
        some promote inflammation
        
        Concentration gradients attract phagocytes to damaged tissue
        
        Some bind to the surface of invading organisms
      - If only a few complement proteins are stimulated, they will trigger others to become active in greater numbers.
      - plasma proteins produced in the liver that will form a cascade effect to destroy the pathogen
- - - - plays a large role in immunity by its participation in leukopoiesis
      - leukocytes (WBC) help to defend the body against foreign molecules
    - - lymph nodes and they are found essentially everywhere in the body
      - tonsils are a type of lymph node as are the adenoids
      - arranged in clusters in the body and function to remove debris and pathogens from the lymph fluid
      - commonly called the "filters" of the lymph
      - All lymph heading to the heart moves through at least one lymph node
      - Lymph nodes are bean-shaped organs and have a hilum like the spleen
      - there are efferent and afferent lymphatic vessels
      - a lot more afferent vessels than efferent vessels and this is important to the function
        
        fluid is kept longer inside lymph node so large molecules end up being trapped and then they can be cleaned up by the macrophages
      - outer part of the lymph node is called the cortex and contains B-cell lymphocytes undergoing mitosis and also T-cell lymphocytes undergoing maturation
      - medulla, the inner core of the lymph node, contains B-cell lymphocytes and plasma cells
  - - - The blood enters and leaves the spleen in the same area: hilum
      - 2 functions:
        
        it filters blood
        
        it acts as part of the immune system
      - in the abdominal cavity on the left side
      - two distinct areas:
        
        Red pulp
        
        filled with blood and handles the filtration of blood
        
        removes the old and damaged erythrocytes from the circulation
        
        white pulp
        
        fulfills the immunological portion of the spleen
        
        contains T-cell lymphocytes, B-cell lymphocytes, and other white blood cells
    - - large gland that sits above the heart
      - in the anterior mediastinum
      - enlarges during childhood but after puberty, it starts to decrease in size until it is extremely small around 50-60 years of age
      - hormone produced in the thymus called thymosin
        
        used for maturation of the T-cell lymphocytes
      - all leukocytes are made in the red bone marrow.
        
        two types
        
        the T-cell lymphocytes
        
        Once made in the red bone marrow they move in the bloodstream to the thymus to mature into one of four types
        
        the B-cell lymphocytes
  - - - T-cell lymphocytes
        
        originate in the red bone marrow
        
        produced in the bone marrow, released while still immature and move through the bloodstream to the thymus for maturation
      - B-cell lymphocytes
        
        produced in the bone marrow and also mature in the bone marrow
    - - ready to battle that same antigen if the body sees it again
- - - - T-killer cells or cytotoxic T cells
        
        contain a cytolytic protein called perforin that can be released to stick to the antigen
        
        This perforin is contained inside the cell with the lysosomes
        
        T-killer cells have recognition proteins on them called CD8
      - T-suppressor cells
        
        call off the attack after it looks like it has been successful
      - T-helper cells
        
        recognize the antigen and call other cells into the area for attack
        
        have recognition proteins on them called CD4
      - T-memory cells
        
        remember that particular antigen and will undergo mitosis to make more cells; if the body is attacked with the same antigen the attack can begin quicker
    - - Destruction of the Enemy
        
        This causes the cytoplasm to leak out, therefore killing the cell
        
        APC cells are now foreign and the T-killer cells release the chemical perforin onto the APC membrane which dissolves holes
      - Call off attack
        
        T-helper cells call in the T-suppressor cells and they release chemicals that call in cells to start the clean-up
      - Proliferation of T-cells
        
        the non-specific defenses are working such as inflammation and fever; makes one feel miserable.
        
        T-helper cells that are already in the area send out chemical signals so more cells will come to the area of infection
        
        has to be more T-helper cells called in along with T-killer cells
      - Future Protection
        
        T-memory cells remember this antigen and proliferate
      - Recognition of Enemy,
        
        The cells release chemicals that signal more macrophages into the area
        
        As macrophages are engulfing the antigens, they become antigen presenting cells (APC)
        
        called macrophages in the tissue as their function has now changed; While trying to engulf the antigen, T-helper cells are activated
        
        All cells contain recognition proteins on their surfaces
        
        glycoproteins (sugar proteins) made by the cell that reside on the outer part of the cell membrane and are used to help recognize self from non-self
        
        called major histocompatibility complexes (MHC)
        
        how the body recognizes an antigen because the antigen recognition protein is not seen as self
        
        Macrophages are monocytes that have moved from the bloodstream into the tissue
        
        steps to a macrophage becoming an APC
        
        macrophage engulfs the antigen
        
        lysosomes in the macrophage are released in the cell which breaks apart the antigen
        
        pieces of the antigen inside the macrophage, glycoproteins made inside the cell pick up pieces and display them on the outside of the macrophage
        
        macrophage contains its own recognition proteins on the cell membrane along with pieces of antigen, they are now foreign and called APC cells
        
        If natural killer cells find an antigen and can't eliminate it, macrophages will move into the area
  - - - made up of 4 polypeptide amino acid chains, two of them called light chains and two of them called heavy chains
      - Light chain= shorter, heavy chain= longer
      - chains are held together by disulfide bonds in a Y-shape
      - The two ends of the Y bind the specific antigens so they can clump them together to take them out of commission
      - An antibody is a protein made by a plasma cell
      - These two ends are called the variable portion as it is the only area that differs between antibodies for different antigens
      - Antibodies are also called immunoglobulins
        
        globulin is a protein so it's a protein for the immune system
        
        5 types of antibodies that are made in the body
        
        IgM: largest of the antibodies as it is made up of 5 units, first antibody made in response to an antigen, not long-lasting
        
        IgG: antibody that takes over after IgM starts to decrease, long-lasting and in greatest quantity, can also move across the placenta to pass immunity into the fetus or embryo
        
        IgA: antibody found in fluids such as tears, saliva and breast milk
        
        IgD: not well understood, found in very low quantities in blood or lymph fluid
        
        IgE: produced against allergies and stimulates cells to produce histamine: reaction that causes tissue swelling and itching; The body is not very effective at fighting allergies
      - Antibodies can attack antigens by agglutination, precipitation and opsonization.
    - - only type of antigen that the particular B-cell will respond to
      - The B-cells have to be activated in order to produce antibodies and this occurs in one of two ways:
        
        The B-cell comes across the specific antigen it codes for
        
        will divide to increase the clone size, called clonal proliferation
        
        Some clones will become plasma cells whose function is to produce the specific antibody that will bind to the antigen
        
        The B-cell comes across the T-helper cell that has already been stimulated by the specific antigen
        
        Since cell-mediated immunity has already begun, the B-cell clonal proliferation occurs at a more rapid rate
      - B-cells have a specific antigen-receptor on their cell membrane
  - - - antibody level rises quickly as the template has already been made; much higher than the primary response
      - After peak, there is a much higher level of antibody that sticks around for a long time
    - - Active Immunity
        
        immunity from actually being exposed to the disease causing organism, long lasting
        
        Artificially-acquired: ex. immunizations
        
        Naturally-acquired : ex. having the disease itself. The body will make its own antibodies
      - Passive immunity
        
        type of immunity acquired by the transfer of antibodies, doesn't last very long and the person is not immune to the disease agent
        
        Naturally-acquired, ex. breastfeeding
        
        Artificially-acquired, ex anti-venom
    - - takes a day or two to start making any antibodies at all and it peaks around 7-10 days
      - antibody level decreases to a pretty low level, after peak
- - - - fluid moves into the interstitial space from the capillary; it brings with it other molecules such as glucose, proteins and hormones
      - ^^^ needed by the tissue cells.
      - pulled by the fluid into the interstitial space
      - pick up the excess water and the cells can pick up the molecules needed
      - some contain receptors for the hormones to bind to in order to allow particular molecules into the cell
      - Wastes also move into the interstitial space and the lymphatic system will help get rid of these
      - too much fluid may flow into the interstitial space
        
        tissues swell causing a condition called edema
        
        large amount of water may not be able to be removed such as in a case of congestive heart failure
    - - right subclavian vein
      - left subclavian vein
      - 2 major collecting ducts in the lymphatic system dump into the subclavian veins^^
        
        thoracic duct
        
        drains fluid from the left side of the head, left arm, left side of the chest, the abdomen and both legs into the left subclavian vein
        
        right lymphatic duct
        
        drains fluid from the right side of the head, right arm and right side of the chest into the right subclavian vein
    - - starts with lymphatic capillaries that run throughout all of our body tissues
      - pick up the fluid lost from the blood capillaries through filtration: lymph fluid
      - beginning of the lymphatic system moving fluid towards the heart
      - As fluid moves towards the heart, the vessels become larger vessels called lymphatic vessels which are very similar to veins in structure
      - not like blood capillaries as they don't lie between arteries and veins