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MaryAnnAnthony.Immune.pdf (Anatomy of Lymphatic System (Lymphoid Cells…
MaryAnnAnthony.Immune.pdf
Anatomy of Lymphatic System
lymphatic vessels - network of vessels -similar in structure to veins - collect excess interstitial fluid and transports it back to the heart
lymphatic capillaries - collect the excess interstitial fluid - contain flap-like mini-valves connected to surrounding structures by collagen filaments
lacteals - specialized lymphatic capillaries in the small intestine - aid in the absorption of lipids
lymph - fluid that enters lymphatic capillaries from the interstitial space
lymph nodes - small organs located along lymphatic vessels that cleanse lymph as it passes through them
lymphatic ducts - vessels that attach to the venous system and allow the lymph to be returned to venous blood - restoring blood volume before blood enters the right atrium
right lymphatic duct - attaches to the intersection of the right subclavian vein and right internal jugular vein
thoracic duct - attaches to the intersection of the left subclavian vein and left internal jugular vein
Lymphoid Cells
Lymphocytes - specialized leukocytes that protect the body against specific foreign antigens - reside in the tissue between patrols of the blood - identifies cells with foreign antigens and mount an immune response
Macrophages - cells that protect the body by phagocytizing foreign material in the lymph - engulf cellular debris/pathogens via phagocytosis
Lymphoid Tissue - collections of reticular CT that house and provide a proliferation site for lymphocytes and provides a surveillance post for lymphocytes and macrophages
Lyphoid organs and their functions
Primary Lymphoid Organs
Red Bone Marrow - collections of Reticular CT - site of production of all lymphocytes and maturation location for lymphocytes being converted into B cells
Thymus - located in superior mediastinum - location that lymphocytes migrate to so they can mature into T cells
Secondary Lymphoid Organs- provide locations for mature lymphocytes to monitor body fluids and have encounters with foreign antigens
lymph nodes - remove cellular debris and microbes from the lymph and allow lymphocytes to interact with the lymph so they can identify specific foreign antigens and mount an immune response
white pulp of the spleen - lymphocyte-rich tissue located around branches of the splenic artery
mucosa-associated lymphoid tissue (MALT) - lymphoid tissues located in mucous membranes - helps protect from pathogens trying to enter the body via these membranes
tonsils - gather and remove pathogens entering the pharynx with food, drink and inhaled air
Peyer's patch - lymphoid follicles in the wall of the ileum - protects the body from bacteria entering the ileum from the colon
appendix - contains high concentration of lymphoid follicles - helps control bacterial populations in the large intestine and stores memory T and B cells
INNATE IMMUNE DEFENSES OF OUR BODY
INTERNAL INNATE DEFENSES: Cells and Chemicals
nonspecific cellular and chemical devices the body uses to identify and incapacitate potentially harmful substances that have breached the surface barriers
phagocytes - capable of engulfing particles via phagocytosis - -neutrophils and macrophages are two most important phagocytes
natural killer (NK) cells -defensive cells that police the body looking for virus-infected and cancerous cells --once target cell is identified the NK cell will stimulate it to undergo apoptosis (a type of cell death where the cell instructs its lysosomes to open inside the cell, digesting and destroying the cell from the inside)
fever - abnormally high body temperature that occurs when leukocytes and/or machrophages encounter invading microbes and release a chemical causing the hypothalamus to reset our basal temperature --also stimulates liver and spleen to store zinc and iron making them unavailable for bacteria to use for replication--increase in basal metabolic rate enhances immune cell activity and speeds up repair processess
antimicrobial proteins - groups of proteins that enhance innate defenses
can lyse and kill certain bacteria - make it easier for phagocytes to bind to pathogens - enhance the inflammatory response
interferons - proteins released by cells that are infected by a virus- sends message to healthy cells nearby that a virus is present which causes them to synthesize proteins that prevent the virus from infecting healthy cells
complement - group of plasma proteins circulating in the blood in an inactive state -activated when they come in contact with antigen-antibody complexes and/or when certain blood factors interact with foreign microbes
inflammatory response - anatomical and physiological changes that occur within injured tissue. Cardinal signs of inflammation are: redness, heat, impairment of movement, pain and edema
2) chemicals released making local capillaries more permeable which allows plasma containing clotting factors to leak into the interstitial space - once in interstitial space clotting proteins activate, mesh of the clot traps pathogens and toxic products, mesh of clot is used as framework to begin repair processes
1) chemicals released causing local arterioles to dilate which increases blood flow to the injured site (increases delivery of materials and temperature)
3) chemicals released to stimulate phagocyte production by the red bone marrow and attracts phagocytes in local capillaries to leave the blood and enter the interstitial space at the injury site
Characteristic clinical sign of acute inflammation - number of neutrophils in blood increases 4-5 times the normal amount
SURFACE BARRIERS - Skin and Mucosae
nearly impenetrable physical barrier that serves as the first line of defense against disease
produce a variety of secretions containing protective chemicals
Antibodies
has two sites built into its structure that are identical to and have the same binding specificity as the receptors of the activated B cell
proteins produced by activated B cells and plasma cells.
antibody is released into body fluids vs B cell receptor which attaches to the B cell's membrane
Antigen-antibody complex - produces defensive effects of body
neutralization -antibodies block sites on a pathogen to prevent it from attaching to body cells
agglutination - binding to antigens on different cells causes the cells to clump together
precipitation - if soluble molecules become interconnected by antibodies they become too large to stay in solution
complement - when activated releases chemical to enhance the inflammatory and immune responses and may lead to cell lysis of the cell the antibody is bound to
Binding of an antibody to its matching antigen forms an antigen-antibody complex
T lymphocytes (cellular immune response)
born in red bone marrow
migrate to thymus for initial maturation
migrate to a secondary lymphoid organ once immunocompetent
once activated, divide to form a clone
clone cells differentiate into effector T cells or memory T cells
Types of T-cells
helper T cells - direct adaptive immune response by activating B cells, other T cells and macrophages
regulatory T cells -slows down the immune response once a foreign antigen is eliminated
cytotoxic T cells - destroy cells identified as non-self
Function of Lymphatic System
body system that collects fluid that has leaked from the blood, cleans it of debris and pathogens, and returns that fluid to the blood
Consists of 3 parts
1) a complex network of lymphatic vessels - transports the fluid
2) lymph -the fluid in the lymphatic vessels
3) lymph nodes - small organs located along lymphatic vessels that cleanse the lymph as it passes through them
Performs 3 functions
1) returns excess interstitial fluid to the blood
2) returns leaked proteins to the blood
3) carries absorbed lipids from the small intestine to the blood