Lymphatic System

Functions of Immune/Lymphatic System It carries fluid from the extracellular space to the bloodstream. It defends the body against disease.

Systems Linked to Immune System Circulatory system: carries lymphocytes, macrophages, antibodies, etc in the blood. Integumentary system: skin is first line of defense, also contains mucous membranes. Endocrine system: thymus and WBC production, hypothalamus and fever.

Nonspecific Mechanisms Physical Barriers: Skin: first line of defense Mucus membranes: in addition to being a barrier, they produce chemicals that may trap microorganisms Infection: Invasion by a pathogen that penetrates the body’s physical barriers

Nonspecific Mechanisms Phagocytosis: ingestion & destruction of particles by specialized cells Phagocyte: Any cell that performs phagocytosis Monocytes and neutrophils: most active WBC in phagocytosis – These cells are wanderers macrophages: Often attached. Mononuclear phagocytic system- lymphatic fluid or blood moves by them, the cells phagocytize foreign particles cleaning the passing fluid.

Nonspecific Mechanisms Natural Killer Cells: WBC that kills invading foreign cells nonspecifically other than by phagocytosis. They kill cancer and virus infected cells by puncturing a hole in the membrane. (due to the change in MHC proteins)

Nonspecific Mechanisms Proteins: Complement: includes more than20 types of plasma proteins that are normally inactive but become activated by the presence of infection. It then labels the invaders so that the phagocytes will attack. Interferon: Main defense against viruses. Cells infected by viruses secrete them. This causes them to diffuse to nearby cells and bind to their membranes. Some how this inhibits proliferation of the virus.

Nonspecific Mechanisms Inflammation: prevents spread of infectious agent, removes dead and damaged cells and prepares for tissue repair. Damaged cells release substances into the blood stream (histamine, serotonin) this causes vasodilation and increase in permeability of blood vessels. = redness, swelling, heat, pain. Edema: fluid leakage into extracellular space Pus: living and non living WBC, platelets, fibrinogen

Specific Mechanisms: Immune Response Components of Immunity: Antigens: substances that provoke an immune response when they enter the body. Could be an organism, toxin, foods, transplanted tissue, etc. Sometimes the body recognizes own cells as antigens = autoimmune disease Antibodies: antigen-antibody complex: a complex that inactivates the effects of the antigen. Produced by lymphocytes immunoglobins (Ig): Proteins with distinct structure involved in different responses.

Specific Mechanisms: Immune Response Lymphocytes: WBC produced in the red bone marrow before birth. T-cells B-cells

Specific Mechanisms: Immune Response T-cells: The ½ of the lymphocytes that migrate to the thymus mature into T-cells. They then migrate to the lymphoid tissue in lymph nodes, spleen, bone marrow, etc. They go through mitosis to replicate. They are very active in destruction of nonself cells. Killer T- cells: specialized in destroying virus-infected cells, cancer cells, and foreign cells. They bind to the non-self cells and release a toxin that causes lyses (cytolytic T-cells)

Specific Mechanisms: Immune Response Helper T-cells: Stimulate defense of other cells. When an antigen is identified, they release proteins into the blood that signal other cells to attack (lymphokines). Stimulate killer T cells to grow and divide, attract neutrophils and monocytes. They also stimulate the division of B cells and their production of antibodies. Suppressor T-cells: slow the defensive mechanism called into action by the helper T cells. This prevents uncontrollable activity that can lead to destruction of healthy self cells. Memory T-cells: provide a memory of the specific antigen that caused the initial sensitization.

Specific Mechanisms: Immune Response B Cells: mature B cells develop from the red bone marrow, spleen, or intestinal wall. They migrate to the lymph nodes and other lymph tissue and accumulate. Sensitization occurs when macrophages bind to an antigen and than process it and express the antigen on its plasma membrane.

Specific Mechanisms: Immune Response Cell- Mediated Immunity: Provided by T-cells. 1. Macrophage IDs antigen. 2. Processes it. 3. Antigen expressed on the membrane. 4. Macrophage presents the antigen to T-cell = T-cell sensitization. 5. T-cell proliferates into varieties of T-cells. The killers can only kill one specific nonself cell. The lymphotoxins can’t finish the job on their own. Assisted by helper T-cells that release lymphokines that call phagocytes into action. This stimulates production of more killer cells and activates humeral immunity. Memory cells serve as rapid recall in subsequent invasions.

Specific Mechanisms: Immune Response Humoral Immunity: B-cells provided. Macrophage id’s an antigen in the body, phagocytizes it and processes it. Presents nonself substance to a B cell. Sensitization and production of B cell lines with help from helper Tells. Become antibody secreting plasma cells and memory B cells.

Specific Mechanisms: Immune Response Humoral Immunity: The Allergic Response: most have a tolerance for many oneself molecules that come into contact with the skin. 10% of individuals are intolerant of many of these antigens = allergic. Plasma cells secrete a different type of antibody IgE (norm IgG or IgM) the IgE antibodies are secreted into the blood come into contact with a mast cell= inflammation, mucus production and hives “anaphylaxis”

Specific Mechanisms: Immune Response Acquired Immunity: ability to mount a defense Acquired Immunity: result of previous contact with antigen Natural Acquired Active Immunity: exposure to pathogens or toxins during daily living. Symptoms of disease expressed the first time because immunity was not acquired before then. Naturally Acquired Passive Immunity: antibodies transferred from an immune person. (pregnancy) short-lived

Specific Mechanisms: Immune Response Artificially Acquired Active Immunity: deliberate artificial introduction of an antigen stimulated immune response. Vaccine Artificially Acquired Passive Immunity: Short-lived immunity – human or animal antibodies may be injected to provide active defense Immune serum globulins.

Explain why “colds” (caused by a virus) usually last about a week? It takes time for the body to respond to the invasion or a virus. The body must first recognize then produce lymphocytes against the new virus. Once these have been made it takes time for these cells to then destroy all of the infected cells.

Why are there certain diseases that you (usually) only get once even if you are continually exposed to them? After the initial exposure your body has created lymphocytes and antibodies against that invader so that if you are infected again the body is able to respond immediately, halting the infection.

How do vaccines help to keep you from getting a disease How do vaccines help to keep you from getting a disease? (Discuss active & passive immunity) They provide a weakened/dead version of an invader that posses little threat to the body but enables the body an opportunity to recognize and form lymphocytes and antibodies against it.

Based on your knowledge of the immune system, summarize several ways for disease causing organisms to EVADE of not get destroyed by the immune system. Some invaders mutate while they are in the body making it necessary to have a T-cell for each new version. (HIV & Influenza) Invaders can produce molecules that inhibit actions of certain leukocytes. They can create molecules the disrupt the antigen presentation process so that the T-cells never bind or never even meet up with the invader.

What is inflammation and how does it help in the immune response? Inflammation is swelling in the area of stress or a disruption to homeostasis that can follow an injury or infection. It aids in the prevention of spreading the infectious agent to nearby tissues and increases the amount of defensive substances (WHB, antibodies, clotting proteins) in the area.

What is pus and why does it form when there is an infections? Pus is a liquid containing blood plasma, dead or dying leukocytes and body cells as well as other cell debris that forms during inflammation.

A student’s spleen is ruptured during a baseball game A student’s spleen is ruptured during a baseball game. What effect might this have on his/her life? The spleen is responsible for creating lymphocytes, removing foreign particles, and damaged cells as well as acting as a blood reservoir. A person who has lost their spleen is more susceptible to infections and must have more immunizations or may be put on an antibiotic regimen. The liver takes over the filtering job of the spleen.

Why are tonsils often removed in childhood? The tonsils can cause common and recurrent tonsillitis (sore throat).

What is germ theory and why is it important in the study of the immune system? Germ theory states that microorganisms are the cause of many illnesses. It is important to study the impact of different microorganisms on the body as well as ways to prevent infection.

Children get ill frequently Children get ill frequently. Is this because children today are often in daycare? Children get sick because they haven’t formed antibodies against common invaders. In daycare they are exposed to more people who may be carrying other illnesses. It wouldn’t any different than when an child initially enters school (just a few years earlier).

What is lymphedema? Lymphedema is the swelling of lymphoid tissue disrupting the flow of interstitial fluid back into the circulatory system.

How does the virus that causes AIDS effect the immune/lymphatic system? The body is continually fighting the AIDS virus lowering its disease fighting ability against other invaders. HIV targets helper T-cells and destroys them. It can destroy 60-90% of all helper T-cells and suppresses cell-mediated immunity.

Describe how the immune system helps/hinders in organ transplants. The immune system recognizes the organ as a foreign invader and will attack and possibly destroy all the tissue if the individual is not given immune system repressing drugs. Individuals on these drugs are more likely to get outside infections if not also put on an antibiotic regimen.

Describe an immunodeficiency disease. (Not AIDS) Severe combined immunodeficiency (SCID): When an individual is born with the inability to produce active T & B cells. DiGeorge’s Syndrome: a congenital disease in which the child is born without the thymus or parathyroid gland.

How can stress effect the immune response? It suppresses the immune system by the release of adrenaline and cortisol (anti-inflammatory) as well as the reducing of blood flow to any non-essential areas.

How can aging effect the immune response? The immune system struggles to distinguish between self and nonself cells. Macrophages are slower to destroy bacteria and cancerous cells. (Another reason why older people are more likely to get cancer.) T-cells respond more slowly Fewer WBC Less antibodies are produced per antigen. (Why vaccines are less effective on older people.)

What is an allergy? When a person is intolerant to the antigens on the surface of a particular kind of molecule.

Bone Marrow: Thymus: Lymph Nodes: Lymphocytes originate here before birth then move to the thymus where they will mature. Thymus: Promotes maturity of lymphocytes into T-lymphocytes. Active only when immune response is developing (birth -5 yrs). Lymph Nodes: They filter lymph of bacteria, toxins, & viruses. The macrophages also engulf damaged cells & cell debris.

Mucosal Associated Lymphoid Tissue: Spleen: Removes foreign particles, old & defective cells & platelets. It also acts as a blood filter and blood reservoirs. Mucosal Associated Lymphoid Tissue: Small concentrations of lymphoid tissue found in various sites of the body such as the gastrointestinal tract, thyroid, breast, lung, salivary glands, eye, and skin. It is populated by lymphocytes such as T cells and B cells, as well as plasma cells and macrophages, each of which is well situated to encounter antigens passing through the mucosal epithelium.

Tonsils/ Adenoids: Appendix: Lymphoid tissue located in the throat region. It gathers & engulfs disease causing organisms in the mouth & throat region. Appendix: In fetuses in produces endocrine cells. In adults it is believed to assist with the maturation of B-cells and production of immunoglobin A antibodies. (Most active in 20’s & 30’s)

Peyer’s Patch: Contains lymphocytes & macrophages that help identify & prevent microorganisms from crossing the intestinal wall.