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48 Cards in this Set
- Front
- Back
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Lymphatic System
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*Returns excess fluid lost from the capillaries back to cardiovascular system. *Plays a major role in defending the body. *Helps absorbs lipids from the small intestine via lacteal |
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Immune system also include:
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Integumentary Digestive system Respiratory System |
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Components of the Lymphatic system
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*Lymph *Lymphatic vessels *Lymphoid Tissues *Lymphoid Organs *Lymphocytes |
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Lymph
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Fluid like plasma but with relatively few suspended proteins
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Lymphatic vessels
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*Vessels that start at the tissues and connect to the veins. *Lymphatic capillaries are the smallest and drain into larger lymphatics. Process is called convergence. * Similar to veins, they have one way valves that keep lymph moving in one direction. **Because of their structure, fluid and other cellular debris can enter the lymphatics but can not leak back into the tissues. |
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Lymphatic vessels has two large connecting vessels.
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Thoracic Duct - drains into left subclavian vein. Right lymphatic duct - drains into right subclavian vein. |
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What happens if lymphatics is blocked?
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Edema - swelling occurs because fluid collects and lymph cannot drain.
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Lymphoid tissues
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These are connective tissues, often areola. These are scattered throughout the body but especially obvious in the: Tonsils Digestive system |
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Tonsils
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Usually 5 in walls of the throat. * palatine tonsils * several lingual tonsils (base of the tongue) * single pharyngeal tonsil aka adenoids |
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Digestive system
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Clusters are found deep into intestinal lining and in the walls of the appendex (a blind pouch near where intestines meet) |
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LYMPHOID ORGANS Lymph Nodes |
* Scattered throughout the body but mostly abundant in the neck, armpits and groin. * Functions like water filters that purify the lymph before it enters he venous blood supply. example - macrophages |
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Macrophages
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A phagocyte cell found in the immune system that, in the lymph node, grab onto pathogens and then present them to lymphocytes for destruction. |
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LYMPHATIC ORGAN Thymus |
Produces hormones that stimulate production and maturation of different types of T-Cells. Thymus secrets several hormones called thymosins. The thymosins stimulate stem cells to eventually produce T-cells. Once mature, t-cells leave thymus and migrate to spleen or other lymphoid tissues. Largest in infants, smallest in elderly. mature, |
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LYMPHATIC ORGAN Spleen |
Largest single collection of lymphoid tissue in the adult body. Works much like lymph nodes except: lymph nodes filter the lymph spleen filters the blood |
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Function of the spleen
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* In filtering the blood, the spleen removes old or damaged RBC's * Stores some iron (recycled from RBC's) * Detects pathogens in the blood and helps initiate immune response by B and T cells. |
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Spleen Anatomy
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Consist of: * Red pulp - mostly rbc's and macrophages * White pulp - lymphoid tissue (mostly lymphocytes) The spleen is relatively fragile and tears easily leading to excessive bleeding. It is difficult to repair since sutures don't hold. Removal = splenectomy (but person will be more susceptible to bacterial infection). |
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Lymphocytes (type of WBC)
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Functions to: Combat pathogens - must be able to detect and reach pathogens or site of infection. (While WBC's circulate in the blood, lymphocytes can readily leave the capillaries and enter the tissues of the body.) |
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Lymphocytes
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Attack pathogens and cancer cells Produced mainly by the red bone marrow As lymphocytes mature in the bone marrow (B-cell) or thymus (T-cell), those that react to itself are destroyed. |
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3 classes of lymphocytes circulate in the body
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T- cells - (thymus dependent) B- cells (bone marrow derived - usually proteins. 10-15% are tied to antibodies) When stimulated, B-cells differentiate into plasma cells, which then produce... NK - cells - roam throughout tissues. "Immunological surveillance" |
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T - Cells
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(thymus dependent) helper cells. 80% of the lymphocytes in circulation |
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B-Cells
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Usually proteins. Are the main cells of humoral immunity (everything outside the blood vessel) Most B cells migrate to spleen, lymph nodes, or other lymphoid tissue Produce plasma cells which makes anti-bodies |
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NK cells (Natural Killer)
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5-10% of lymphocytes in circulation. These patrol throughout the body for abnormal cells. NK cells attack: - foreign cells - normal body cells infected with - cancer cells |
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The body has 2 broad category of defenses:
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Non specific Specific |
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Non-Specific Defenses
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- Those that help defend against invasion in general and respond the same regardless of the exact threat. aka innate defenses because they are present from birth |
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7 major categories of non-specific defenses
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External barriers Phagocytes Immunological surveillance (NK cells) Compliment proteins (MAC) Inteferons Inflammation Fever |
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External Barriers
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Skin Mucous Membranes * lysosomes: an enzyme found in saliva, mucus, and tears that attacks the cell wall of many bacteria. |
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Phagocytes - first line of cellular defense
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Neutrophils Eosinophils Monocytes Macrophages Some roam throughout the body, others are fixed and reside permanently in lymph nodes, spleen for example. After they ingest a pathogen, its destroyed with a lysosome. |
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Immunological Surveillance
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NK (Natural Killer) cells constantly monitor the tissues for abnormal cells (usually an abnormal protein on its surface) NK cells are versatile. They can attack bacteria, virus-infected cells and cancerous cells. NK cells destroy pathogens upon contact and thus act much faster than T or, B- cells |
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Perforins
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Proteins secreted by NK cells. These are secreted into the pathogens membrane. Perforins create pores in the membrane which cause it to lyse (split open) |
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Compliment Proteins
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Plasma contains about 11 different antimicrobial proteins. Attract phygocytes (eosinophil, neutrophils, macrophages) Stimulate inflammation |
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Interferons
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Small proteins released by activated lymphocytes and macrophages and by cells infected w/ viruses. Function as hormones that bind to cell membrane receptors of normal cells. This causes these cells to produce antiviral proteins. Interferons prevent viruses from replicating |
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Inflammation
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Local swelling increased blood flow, heat, and pain - attracts neutrophils to the area which in turn attracts other WBCs - increased local temps accelerates the activity of phagocytes and enzymes |
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Fever
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Macrophages may release pyrogens - pyrogens (circulating proteins that can reset the thermostat in the hypothalamus) Higher body temps 1. increases our metabolism 2. may inhibit some viruses and bacteria |
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SPECIFIC DEFENSES
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- Immune system aims at a single target (highly specific viral strain) - AKA The immune response - Lymphocytes provide a specific defense |
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Four (4) features characterize the immune response.
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Specificity Versitility Tolerence Memory |
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Specificty
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Host produce antibodies or T-Cells that are specific for each antigen. Occurs because each T or B-Cell has receptors that will bind to only one specific antigen |
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Versitility
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Ability to respond to a huge diversity of invaders. Our bodies contain millions of different lymphocytes but maybe only 1000 of each type. However, when one type gets activated by a specific antigen it rapidly produce many copies of itself. |
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Tolerance
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The immune system does not respond to all antigens. Some it tolerates, especially those it recognizes as part of its own body.
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Memory
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After responding to a particular pathogen once, the immune system "remembers". This is because activated lymphocytes (B or T cells) produced 2 types of daughter cells: * Active cells - (may only live a few days) attack the antigen * Memory cells - cells that remain inactive until exposed to that same pathogen in the future. May live for 20+ years. |
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There are 2 interactive immunity responses
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Anti-body mediated immunity - aka humoral immunity. Largely through the B-cell Cell-mediated immunity - aka cellular immunity. Largely through the T-cell ***These two immune responses work simultaneously and cooperatively |
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Antibody mediated immunity
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(aka humoral immunity) In general B cells defend against pathogens in the body fluid. Advantage to this is that antibodies can quickly spread and distributed and attack the pathogen wherever it occurs in the body. Some T-cells called helper T-cells stimulate the activity of B cells in the body |
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Cell mediated immunity
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(aka cellular immunity) T-cells defend against abnormal cells and pathogens inside cells. Antibodies don't help if cells are infected because antibodies cannot cross the phosolipid bilayer because they are big proteins. |
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Forms of immunity |
Innate immunity - is genetically determined doesn't require prior exposure to an antigen. Acquired immunity - not present at birth. We become immune to a specific antigen only after being exposed to it. |
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Forms of acquired immunity
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Active immunity - the body responds to an antigen by making its own antibody (the immune response). Passive Immunity - produced by or transfer of antibodies from another person |
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At what age does a person immune to the greatest number of threats?
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In general, mid-old to old age |
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Active Immunity
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- these antibodies often develop after natural exposure to pathogens throughout our lives - or, you might produce them after being induced to do so. Ex vaccination |
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Passive Immunity
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Produced by transfer of antibodies from another person even though they may be naturally acquired. Ex. From your mother via breastmilk; Or injected into a patient. Ex. Antibodies against the rabies virus into a person bitten by a rabid snake |
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