what causes the flow of lymph to slow within lymph nodes?

LYMPHATIC Arrangement AND IMMUNITY.

The Lymphatic System | Immunity | General Defenses | Specific Defenses

Antibody-mediated Immunity | Blood Types, Rh, and Antibodies

Organ Transplants and Antibodies | Allergies and Disorders of the Immune Organisation

Links

The Lymphatic Organization | Back to Top

The lymphatic organization is composed of lymph vessels, lymph nodes, and organs. The functions of this system include the absorbtion of backlog fluid and its return to the claret stream, absorption of fat (in the villi of the small intestine ) and the immune system function.

Lymph vessels are closely associated with the circulatory arrangement vessels. Larger lymph vessels are similar to veins. Lymph capillaries are scatted throughout the body. Wrinkle of skeletal muscle causes move of the lymph fluid through valves.

Lymph organs include the bone marrow, lymph nodes, spleen , and thymus. Bone marrow contains tissue that produces lymphocytes . B-lymphocytes (B-cells) mature in the bone marrow. T-lymphocytes (T-cells) mature in the thymus gland. Other blood cells such as monocytes and leukocytes are produced in the bone marrow. Lymph nodes are areas of concentrated lymphocytes and macrophages along the lymphatic veins. The spleen is similar to the lymph node except that it is larger and filled with blood. The spleen serves every bit a reservoir for blood, and filters or purifies the blood and lymph fluid that flows through it. If the spleen is damaged or removed, the individual is more susceptible to infections. The thymus secretes a hormone, thymosin, that causes pre-T-cells to mature (in the thymus) into T-cells.

Immunity | Back to Top

Immunity is the body's capability to repel foreign substances and cells. The nonspecific responses are the first line of defense. Highly specific responses are the second line of defense and are tailored to an private threat. The allowed response includes both specific and nonspecific components. Nonspecific responses block the entry and spread of disease-causing agents. Antibiotic-mediated and cell-mediated responses are two types of specific response. The immune system is associated with defense against disease-causing agents, problems in transplants and blood transfusions, and diseases resulting from over-reaction (autoimmune, allergies) and under-reaction (AIDS).

General Defenses | Back to Peak

Barriers to entry are the skin and mucous membranes. The skin is a passive barrier to infectious agents such every bit bacteria and viruses. The organisms living on the skin surface are unable to penetrate the layers of dead pare at the surface. Tears and saliva secrete enzymes that breakdown bacterial cell walls. Skin glands secrete chemicals that retard the growth of bacteria. Fungus membranes lining the respiratory, digestive, urinary, and reproductive tracts secrete mucus that forms another barrier. Physical barriers are the first line of defence force.

When microorganisms penetrate skin or epithelium lining respiratory, digestive, or urinary tracts, inflammation results. Damaged cells release chemical signals such as histamine that increment capillary blood catamenia into the afflicted surface area (causing the areas to become heated and reddened). The oestrus makes the environment unfavorable for microbes, promotes healing, raises mobility of white claret cells, and increases the metabolic rate of nearby cells. Capillaries pass fluid into interstitial areas, causing the infected/injured area to dandy. Clotting factors trigger formation of many small blood clots. Finally, monocytes (a type of white blood cell) make clean up expressionless microbes, cells, and debris.

The inflammatory response is often strong plenty to cease the spread of disease-causing agents such as viruses, leaner, and fungi. The response begins with the release of chemic signals and ends with cleanup by monocytes. If this is non enough to stop the invaders, the complement arrangement and immune response act.

Protective proteins that are produced in the liver include the complement organization of proteins. The complement system proteins bind to a bacterium and open up pores in its membrane through which fluids and common salt motility, swelling and bursting the cell.

The complement organization directly kills microbes, supplements inflammatory response, and works with the immune response. It complements the actions of the allowed system. Complement proteins are made in the liver and become active in a sequence (C1 activates C2, etc.). The final 5 proteins form a membrane-assail complex (MAC) that embeds itself into the plasma membrane of the attacker. Salts enter the invader, facilitating water to cross the membrane, swelling and bursting the microbe. Complement also functions in the immune response by tagging the outer surface of invaders for attack past phagocytes .

The complement system of proteins and their performance. Paradigm from Purves et al., Life: The Science of Biology, 4th Edition, by Sinauer Associates (www.sinauer.com) and WH Freeman (www.whfreeman.com), used with permission.

Interferon is a species-specific chemic produced by cells that are viral attack. It alerts nearby cells to prepare for a virus. The cells that have been contacted by interferon resist all viral attacks.

Specific Defenses | Back to Top

The immune arrangement also generates specific responses to specific invaders.

The immune system is more constructive than the nonspecific methods, and has a memory component that improves response time when an invader of the same blazon (or species) is again encountered.

Amnesty results from the production of antibodies specific to a given antigen (antibody-generators, located on the surface of an invader). Antibodies bind to the antigens on invaders and kill or inactivate them in several ways. Well-nigh antibodies are themselves proteins or are a mix of protein and polysaccharides. Antigens tin can exist any molecule that causes antibody production.

Lymphocytes

White blood cells known as lymphocytes arise from past mitosis of stem cells in the bone marrow. Some lymphocytes migrate to the thymus and get T cells that circulate in the blood and are associated with the lymph nodes and spleen. B cells remain in the os marrow and develop earlier moving into the circulatory and lymph systems. B cells produce antibodies.

Macrophage Attacking E.coli (SEM x8,800). This image is copyright Dennis Kunkel at www.DennisKunkel.com, used with permission.

Antibody-mediated (humoral amnesty)

Antibody-mediated (humoral) immunity is regulated by B cells and the antibodies they produce. Jail cell-mediated immunity is controlled by T cells. Antibiotic-mediated reactions defend confronting invading viruses and bacteria. Prison cell-mediated immunity concerns cells in the trunk that have been infected by viruses and bacteria, protect against parasites, fungi, and protozoans, and also kill malignant body cells.

Homo T-lymphocyte (SEM x12,080). This image is copyright Dennis Kunkel at www.DennisKunkel.com, used with permission.

The cell-mediated immune responses. Images from Purves et al., Life: The Science of Biology, fourth Edition, by Sinauer Associates (www.sinauer.com) and WH Freeman (www.whfreeman.com), used with permission.

Antibody-mediated Amnesty | Dorsum to Peak

Stages in this process are:

antigen detection
activation of helper T cells
antibiotic production past B cells

Each stage is directed by a specific cell type.

Macrophages

Macrophages are white claret cells that continually search for foreign (nonself) antigenic molecules, viruses, or microbes. When found, the macrophages engulfs and destroys them. Small fragments of the antigen are displayed on the outer surface of the macrophage plasma membrane.

The role of macrophages in the formation of antibodies. Image from Purves et al., Life: The Science of Biology, 4th Edition, by Sinauer Associates (www.sinauer.com) and WH Freeman (www.whfreeman.com), used with permission.

Helper T Cells

Helper T cells are macrophages that become activated when they encounter the antigens now displayed on the macrophage surface. Activated T cells identify and actuate B cells.

The display path of an antigen every bit accomplished by a macrophage. Image from Purves et al., Life: The Science of Biology, 4th Edition, by Sinauer Associates (www.sinauer.com) and WH Freeman (www.whfreeman.com), used with permission.

B Cells

B cells divide, forming plasma cells and B memory cells . Plasma cells make and release between 2000 and 20,000 antibody molecules per 2nd into the claret for the side by side four or v days. B retention cells live for months or years, and are part of the immune retentiveness organization.

The activation of T cells by the action of macrophages and interleukin-2. Images from Purves et al., Life: The Scientific discipline of Biological science, 4th Edition, past Sinauer Assembly (world wide web.sinauer.com) and WH Freeman (www.whfreeman.com), used with permission.

Antibodies

Antibodies bind to specific antigens in a lock-and-key manner, forming an antigen-antibody complex. Antibodies are a blazon of protein molecule known equally immunoglobulins . There are 5 classes of immunoglobulins: IgG, IgA, IgD, IgE, and IgM.

The five classes of Ig antibodies. Image from Purves et al., Life: The Science of Biology, 4th Edition, past Sinauer Associates (www.sinauer.com) and WH Freeman (www.whfreeman.com), used with permission.

Antibodies are Y-shaped molecules equanimous of two identical long polypeptide (Heavy or H chains) and ii identical curt polypeptides (Calorie-free or L chains). Function of antibodies includes:

Recognition and binding to antigens
Inactivation of the antigen

Structural regions of an antibiotic molecule. Epitome from Purves et al., Life: The Science of Biology, 4th Edition, by Sinauer Assembly (world wide web.sinauer.com) and WH Freeman (www.whfreeman.com), used with permission.

A unique antigenic determinant recognizes and binds to a site on the antigen, leading to the devastation of the antigen in several means. The ends of the Y are the antigen-combining site that is dissimilar for each antigen. Click here to acquire more almost the different classes of antibodies.

Formation of an antigen-antibody complex. Prototype from Purves et al., Life: The Scientific discipline of Biology, 4th Edition, past Sinauer Associates (world wide web.sinauer.com) and WH Freeman (www.whfreeman.com), used with permission.

Helper T cells activate B cells that produce antibodies. Supressor T cells slow down and stop the immune response of B and T cells, serving every bit an off switch for the immune system. Cytotoxic (or killer) T cells destroy body cells infected with a virus or bacteria. Retention T cells remain in the body awaiting the reintroduction of the antigen.

A jail cell infected with a virus will display viral antigens on its plasma membrane. Killer T cells recognize the viral antigens and adhere to that cell's plasma membrane. The T cells secrete proteins that punch holes in the infected prison cell's plasma membrane. The infected jail cell's cytoplasm leaks out, the prison cell dies, and is removed by phagocytes. Killer T cells may also bind to cells of transplanted organs.

The immune system is the major component of this defense. Lymphocytes, monocytes, lymph organs, and lymph vessels brand up the system. The immune system is able to distinguish self from non-self. Antigens are chemicals on the surface of a jail cell. All cells accept these. The allowed organisation checks cells and identifies them as "self" or "not-self". Antibodies are proteins produced past certain lymphocytes in response to a specific antigen. B-lymphocytes and T-lymphocytes produce the antibodies. B-lymphocytes become plasma cells which then generate antibodies. T-lymphocytes assault cells which bear antigens they recognize. They too mediate the immune response.

The immune system and memory of infections

Secondary immunity, the resistance to sure diseases after having had them one time, results from production of Memory B and T cells during the first exposure to the antigen. A second exposure to the aforementioned antigen produces a more than massive and faster response. The secondary response is the basis for vaccination.

Vaccination

Vaccination is a term derived from the Latin vacca (cow, later on the cowpox material used by Edward Jenner in the beginning vaccination). A vaccine stimulates the antibody production and formation of retentivity cells without causing of the disease. Vaccines are made from killed pathogens or weakened strains that cause antibody product merely not the affliction. Recombinant Deoxyribonucleic acid techniques can now be used to develop fifty-fifty safer vaccines.

The immune system tin can develop long-term immunity to some diseases. Man tin can utilise this to develop vaccines, which produce induced immunity. Active immunity develops after an affliction or vaccine. Vaccines are weakened (or killed) viruses or bacteria that prompt the development of antibodies. Application of biotechnology allows development of vaccines that are the protein (antigen) which in no way can cause the disease. Passive immunity is the type of immunity when the individual is given antibodies to combat a specific affliction. Passive amnesty is short-lived.

Claret Types, Rh, and Antibodies | Back to Summit

There are thirty or more than known antigens on the surface of claret cells. These class the blood groups or blood types. In a transfusion, the blood groups of the recipient and donor must exist matched. If improperly matched, the recipient's immune system will produce antibodies causing clotting of the transfused cells, blocking circulation through capillaries and producing serious or even fatal results.

ABO blood types are determined by a gene, I (for isoagglutinin). There are three alleles, I^A, I^B and I^O. Proteins produced by the A and B alleles are antigenic. Individuals with blood type A accept the A antigen on the surface of their cherry claret cells, and antibodies to blazon B blood in their plasma. People with blood type B have the B antigen on their blood cells and antibodies confronting type A in their plasma. Individuals with type AB claret produce have antigens for A and B on their jail cell surfaces and no antibodies for either claret type A or B in their plasma. Type O individuals take no antigens on their ruby-red blood cells simply antigens to both A and B are in their plasma.

People with type AB blood can receive blood of any type. Those with type O blood can donate to anyone. If a transfusion is fabricated betwixt an incompatible donor and recipient, the recipient's claret volition undergo a cascade of events. Reaction of antigens on cells and antibodies in plasma will produce clumping that clogs capillaries, other cells outburst, releasing hemoglobin that can crystallize in the kidney and lead to kidney failure.

The Rh (for the rhesus monkey in which it was discovered) claret group is made upward of those Rh positive (Rh⁺) individuals who tin can make the Rh antigen and those Rh negative (Rh^-) who cannot.

Hemolytic affliction of the newborn (HDN) results from Rh incompatibility between an Rh^- mother and Rh⁺ fetus. Rh⁺ blood from the fetus enters the mother'due south system during birth, causing her to produce Rh antibodies. The beginning child is normally non affected, yet subsequent Rh⁺ fetuses will cause a massive secondary reaction of the maternal immune system. To prevent HDN, Rh- mothers are given an Rh antibody during the starting time pregnancy with an Rh+ fetus and all subsequent Rh+ fetuses.

Organ Transplants and Antibodies | Back to Superlative

Success of organ transplants and skin grafts requires a matching of histocompatibility antigens that occur on all cells in the torso. Chromosome 6 contains a cluster of genes known as the human leukocyte antigen complex (HLA) that are disquisitional to the outcome of such procedures. The array of HLA alleles on either copy of our chromosome six is known as a haplotype.

The large number of alleles involved mean no two individuals, fifty-fifty in a family unit, will have the same identical haplotype. Identical twins have a 100% HLA match. The best matches are going to occur inside a family. The preference order for transplants is identical twin > sibling > parent > unrelated donor. Chances of an unrelated donor matching the recipient range between 1 in 100,000-200,000. Matches across racial or ethnic lines are frequently more difficult. When HLA types are matched survival of transplanted organs dramatically increases.

Allergies and Disorders of the Immune System | Back to Meridian

The immune arrangement can overreact, causing allergies or autoimmune diseases. Likewise, a suppressed, absent, or destroyed immune system tin can also event in affliction and decease.

Allergies result from immune system hypersensitivity to weak antigens that practice not crusade an immune response in virtually people. Allergens , substances that cause allergies, include grit, molds, pollen, cat dander, certain foods, and some medicines (such as penicillin). Up to 10% of the US population suffer from at least one allergy.

After exposure to an allergen, some people make IgE antibodies as well equally B and T retentivity cells. Subsequent exposure to the same allergen causes a massive secondary immune response that releases enough of IgE antibodies. These bind to mast cells found usually in connective tissues surrounding blood vessels. Mast cells then release histamine, which starts the inflammatory response. In some individuals the histamine release causes life-threatening anaphylaxis or anaphylactic shock.

The immune system usually distinguishes "self" from "nonself". The immune system learns the divergence between cells of the torso and foreign invaders. Autoimmune diseases consequence when the allowed system attacks and destroys cells and tissues of the body. Juvenile diabetes, Grave's disease, Multiple sclerosis, Systemic lupus erythematosus, and Rheumatoid arthritis are some of the autoimmune diseases.

Myasthenia gravis (MG) is a musculus weakness acquired past destruction of muscle-nerve connections. Multiple sclerosis (MS) is caused by antibodies attacking the myelin of nerve cells. Systemic lupus erythematosis (SLE) has the person forming a series of antibodies to their ain tissues, such equally kidneys (the leading crusade of death in SLE patients) and the DNA in their ain cellular nuclei. In systemic lupus erythematosus (SLE), the immune system attacks connective tissues and major organs of the body. Rheumatoid Arthritis ; sufferers have damage to their joints. Some bear witness supports Type I diabetes every bit an automobile immune disease. Juvenile diabetes results from the destruction of insulin-producing cells in the pancreas.

Immunodeficiency diseases result from the lack or failure of one or more parts of the allowed organisation. Afflicted individuals are susceptible to diseases that normally would not bother about people. Genetic disorders, Hodgkin's disease, cancer chemotherapy, and radiation therapy can cause immunodeficiency diseases.

Astringent Combined Immunodeficiency (SCID) results from a complete absenteeism of the cell-mediated and antibody-mediated immune responses. Afflicted individuals suffer from a series of seemingly minor infections and usually die at an early age. A minor group suffering from adenosine deaminase (ADA) deficiency, a blazon of SCID, are undergoing cistron therapy to provide them with normal copies of the defective factor.

Acquired Immunodeficiency Syndrome (AIDS) is currently receiving the nigh attention among the immunodeficiency diseases. AIDS is a drove of disorders resulting from the devastation of T cells by the Human being Immunodeficiency Virus (HIV) , a retrovirus . When HIV replicates in the human T cells, it buds from the T prison cell plasma membrane encased in a glaze derived from the T cell plasma membrane. HIV selectively infects and kills T4 helper cells. The viral RNA is converted into DNA by the enzyme reverse transcriptase ; this DNA tin can become incorporated into a man chromosome for months or years.

Construction and replication cycle of HIV. Images from Purves et al., Life: The Science of Biology, fourth Edition, past Sinauer Associates (www.sinauer.com) and WH Freeman (www.whfreeman.com), used with permission.

When the infected T jail cell is needed in the immune response, the viral genes are activated and the virus replicates, killing the infected cell and producing a new round on T4 cell infection. Gradually the number of T4 cells, the primary on switch for the allowed system, decline. The immune response grows less powerful, somewhen failing. Premature decease results from a series of rare diseases (such as fungal pneumonia and Kaposi's sarcoma, a rare cancer) that overwhelm the torso and its compromised immune arrangement.

Links | Back to Top

AIDS: The War Within Museum of Science and Industry, Chicago. A very nicley illustrated series of pages that walk you through the replication/infection cycle of HIV.
Our Immune System Written past Sara Le Bien, this site uses clever cartoon T and B cells to explain the office of the allowed syste. Very worth a visit.
Jerry's Immunology Page
Immunology and AIDS Another fine problem set with tutorials from the University of Arizona's Biological science Project.
What The Heck Does Protease Inhibitor Accept To Practice With HIV? An article from "Bugs in the News"
Immunology Problem Prepare Another fine problem set with tutorials from the University of Arizona's Biological science Project. Equally of 4/21 the tutorials were not however online but were expected before long.
The Lupus Foundation of America Learn about a serious illness and some of the treatment options.
SLE Lupus A page on "the bang-up imposter" by the National Jewish Medical Enquiry Center
The Lupus Dwelling Page Hamline Academy
Cells Alive! Excellent coverage of a range of immune-related topics, including inflammation and AIDS.
Microbiology Video Library Beware....some of these files are large and non for the faint-of-modem!
Welcome to Histo A site defended to the Major Histocompatibility Complex. I can't wait!
Dr. Kadar'due south Immune Organisation Folio
Bloodline: The Online Hematology Resource
Cells of the Blood A cool interface by clicking of a type of blood jail cell.
Atlas of Hematology Nagoya Academy Schoolhouse of Medicine
Inflammation and Fever An online book that I was ferverish to end.
Amnesty Full text and graphics (after 1 May) from a journal devoted to amnesty.
Cancer and the Immune Organisation The Cancer Research Found presents a tasty series of graphics detailing the immune response to malignant cells.
Development of Vaccines to Infectious Diseases Brown Academy page for BIO 160.

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