Lymphatic System

1. Lymphatic System Mrs. Penley

2. Lymph • The fluid that leaves capillaries and goes into tissues • It flows TOWARDS the heart only

3. These mechanisms help lymph return to the heart & bloodstream: • Valves in lymph vessels • Smooth muscle contractions • Pressure changes • Contraction of skeletal muscles

4. Lymph Nodes

6. Lymph nodes act as… • Filters • Remove foreign materials • Contain lymphocytes (T cells) http://www.youtube.com/watch?v=RO6qmpApyDM • Contain macrophages http://www.youtube.com/watch?v=7WGyq82oMkM

7. Characteristics of macrophages • Act as antigen presenters • Engulf foreign particles • Secrete monokines • Considered “big eaters” of immune system

8. Immunology • The study of immunity

9. What is an antigen? • An antigen is any substance that causes your immune system to produce antibodies against it. • An antigen may be a foreign substance from the environment such as chemicals, bacteria, fungi, viruses, or pollen grains. • An antigen may also be formed within the body, as with bacterial toxins or tissue cells.

10. What is an antibody? • Antibodies are large Y-shaped proteins. • They are recruited by the immune system to identify and neutralize foreign objects like bacteria and viruses. • Each antibody has a unique target known as the antigen present on the invading organism. • This antigen is like a key that helps the antibody in identifying the organism. This is because both the antibody and the antigen have similar structure at the tips of their “Y” structures. • Just like every lock has a single key, an antibody has a single antigen key. When the key is inserted into the lock, the antibody activates, tagging or neutralizing its target. • The production of antibodies is the main function of the humoral immune system. • http://www.news-medical.net/health/Antibody-What-is-an-Antibody.aspx

11. Classes of antibodies • Antibodies are composed of a light chain protein and a heavy chain protein that come together and form a Y-shaped structure. • The base of the Y is a conserved region that all antibodies have in common, while the tips of the forks of the Y are unique to each antibody. • The tips react with the antigen, while the conserved base interacts with the immune system. • Five types of antibodies are formed in the body: IgG, IgM, IgA, IgD and IgE (notice they spell MADGE)

12. IgG • Immunoglobulin G (IgG) is the most abundant circulating antibody, making up 80% of the total antibodies and 75% of that found in serum. • It contains a single antibody protein complex, with two heavy chains and two light chains. • IgGis the second type of antibody synthesized in response to an infection and is the only antibody that can pass through the wall of small blood vessels to access antigens present in the extracellular spaces. • It is also the only antibody capable of crossing the placenta in humans, where it confers the mother's immunity onto the fetus and newborn. • This immunity protects a baby for the first 6-12 months of its life and allows it time for its own immune system to mature. • IgGis particularly effective at attacking extracellular viruses and protein toxins and is also capable of activating the classic pathway of the complement cascade. It helps to prevent the systemic spread of infection and facilitates recovery from many infections. • Finally, IgG is the antibody that serves as an efficient handle for phagocytes

13. IgM • IgM is the largest antibody, with five Y structures being joined by their Fc regions in a circular configuration. • A J chain (another polypeptide) links the five antibodies together. IgM is present in serum, making up about 10 % of antibodies in the blood. • The presence of its ten antigen reactive sites helps agglutinate or clump antigens (see the explanation of this term in the next section), making it easier for the immune system to eliminate them. • IgMis more efficient than IgG at activating the complement pathway. • IgMis synthesized by plasma cells early in a primary infection and is very important in slowing or stopping the spread of a pathogen during the initial stages of an illness. • IgMis also found on mature B cells in a monovalent form, where it serves as a receptor.

14. IgA • IgA is present in serum, mucus, saliva, tears, sweat and milk. • Two subclasses with different heavy chains are made, IgA1 and IgA2. IgA1 is synthesized in the bone marrow and makes up most of the serum IgA. • IgA2 is synthesized by B cells present in MALT (mucosa-associated lymphoid tissue). NOTE: MALT includes your tonsils & Peyer’s patches • IgA in breast milk interferes with the colonization of the GI tract by harmful microorganisms in the first few months of life. The mother's IgA in the GI tract of newborns keeps these pathogens at low populations, preventing them from causing serious disease, but still allowing the stimulation of the infant's own immune system. The newborn thus develops its own immunity while being partially protected by the mother. IgA molecules do not activate the classical complement pathway, but may activate the alternative complement pathway.

15. IgE • IgE is a monomeric antibody that accounts for only 0.002 % of the total serum antibodies. • Almost all IgE is bound to tissue cells, especially mast cells and eosinophils in various parts of the body. • Contact of IgE with antigen leads to release of a set of signal molecules from the mast cells, which effectively recruits various agents of the immune response to fight the infection. • IgEand MALT serve to detect penetrating pathogens and amplify the immune response in an area leading to the repulsion of the invader. • Antigen reactions with IgE are also responsible for atopic allergic reactions (e.g., hives, asthma, hay fever etc.)

16. IgD • IgD is found on the surface of B-lymphocytes and together with monomeric IgM, serves as antigen receptor for the activation of B cell as described previously. • IgDis monovalent (one site of attachment).

17. Whoa…What’s the difference between those T-cells and B-cells, anyway? • Let’s take a breather and do a little thoughtful Ed activity here. • Compare and Contrast T-cells and B-cells

18. Some things you should have gleaned from your activity…. • B cell and T cell are lymphocytes responsible for the third line of defense in your body. Basically defending your body from invading antigens (i.e. germs). The main difference between the two are: - B cell are responsible for the antibody-mediated response while T cells are responsible for cell-mediated response.- B cell produced in bone marrow. T cell produced in bone marrow & lymph nodes. - When detected antigen, B cell undergoes clonol expansion and create different B cell, some are memory B cell which remembers the germ. Most become plasma cells which produces antibody (germ killer) to fight the antigen. - T cell's main role is to destroy infected cells and cancer cells and to coordinate acquired immune response. • Note: Antigen presentation is necessary for the activation and cloning of T-cells.

19. Some ways they are alike… • Each B cell and T cell is specific for a particular antigen. What this means is that each is able to bind to a particular molecular structure. • They are integral membrane proteins. • They are present in thousands of identical copies exposed at the cell surface. • They are made before the cell ever encounters an antigen. • They are encoded by genes assembled by the recombination of segments of DNA.

20. How do antibodies inactivate antigens? • 1. They complement fixation • 2. Precipitation • 3. Agglutination • 4. Neutralization

21. Complement fixation • Complement fixation. Antibodies IgM and IgG bind to enemy cells and change shape, exposing their complement-binding sites • This initiates the binding of complement to the enemy cell surface and leads to inflammation, phagocytosis, immune clearance, and cytolysis • Complement fixation is the primary mechanism of defense against foreign cells such as bacteria and mismatched erythrocytes. • It makes it easier for phagocytes to ingest and destroy bacteria.

22. Precipitation • a similar process in which antibodies link antigen molecules (not whole cells) together. • This creates large Ag–Ab complexes that are too large to remain dissolved in solution. • These complexes can be removed by immune clearance or phagocytized by eosinophils in the connective tissues.

23. Agglutination • It is effective not only in mismatched blood transfusions, but more importantly as a defense against bacteria. • An antibody molecule has 2 to 10 binding sites; thus, it can bind to antigen molecules on two or more enemy cells at once and stick them together • This immobilizes microbes and antigen molecules and prevents them from spreading through the tissues.

24. Neutralization • Only certain regions of an antigen are pathogenic—for example, the parts of a toxin molecule or virus that enable these agents to bind to human cells. • Antibodies can neutralize an antigen by masking these active regions (i.e. The antibodies bind to specific sites on bacteria toxins and block their “bad” effects) .

25. Chemotaxis • The migration of phagocytes and WBCs (white blood cells) to an inflamed area along a chemical gradient • Q: When would this happen?

26. The body’s 1st line of defense • Skin & mucous membranes

27. The body’s non-specific defenses include: • Fever • Inflammatory response • Intact skin • Natural killer cells (these are not to be confused with T or B cells) http://www.youtube.com/watch?v=HNP1EAYLhOs

28. The inflammatory Response • The inflammatory response is the body's natural response that occurs immediately following tissue damage. • It's main functions are to defend the body against harmful substances, dispose of dead or dying tissue and to promote the renewal of normal tissue.

29. Characteristics of inflammatory response include… • Pain (due to chemicals released by damaged cells). • Swelling or Edema (due to an influx of fluid into the damaged region). • Redness (due to vasodilatation- the widening of blood vessels and bleeding in the joint or structure). • Heat (due to an increase in blood flow to the area). • Loss of function (due to increased swelling and pain). http://www.youtube.com/watch?v=_bNN95sA6-8

30. Chemicals released during the inflammatory response do the following… • Dilate the blood vessels • Capillaries become leaky • Attract phagocytes • Activate natural pain receptors

31. The immunity you receive from a vaccine • Artificially acquired active immunity

32. Lymphatic system organs • Spleen • Tonsils • Thymus • Peyer’s Patches

33. Spleen

34. The spleen destroys worn out red blood cells. • It is located in the upper far left part of the abdomen, to the left of the stomach. • The spleen varies in size and shape between people, but it’s commonly fist-shaped, purple, and about 4 inches long. • The spleen also helps fight certain kinds of bacteria that cause pneumonia and meningitis

35. Spleen conditions • Enlarged Spleen (Splenomegaly): An enlarged spleen, usually caused by viral mononucleosis (“mono”), liver disease, blood cancers (lymphoma and leukemia), or other conditions. • Ruptured spleen: The spleen is vulnerable to injury, and a ruptured spleen can cause serious life-threatening internal bleeding and is a life-threatening emergency. An injured spleen may rupture immediately after an injury, or in some cases, days or weeks after an injury. • Sickle cell disease: In this inherited form of anemia, abnormal red blood cells block the flow of blood through vessels and can lead to organ damage, including damage to the spleen. People with sickle cell disease need immunizations to prevent illnesses their spleen helped fight. • Thrombocytopenia (low platelet count): An enlarged spleen sometimes stores excessive numbers of the body’s platelets. Splenomegaly can result in abnormally few platelets circulating in the bloodstream where they belong.

36. Tonsils

37. The tonsils (palatine tonsils) are a pair of soft tissue masses located at the rear of the throat (pharynx). • Each tonsil is composed of tissue similar to lymph nodes, covered by pink mucosa (like on the adjacent mouth lining). Running through the mucosa of each tonsil are pits, called crypts.

38. Tonsil Conditions • Acute tonsillitis: A bacteria or virus infects the tonsils, causing swelling and a sore throat. The tonsil may develop a gray or white coating (exudate). • Chronic tonsillitis: Persistent infection of the tonsils, sometimes as a result of repeated episodes of acute tonsillitis. • Peritonsillar abscess: An infection creates a pocket of pus next to the tonsil, pushing it toward the opposite side. Peritonsillar abscesses must be drained urgently. • Acute mononucleosis: Usually caused by the Epstein-Barr virus, “mono” causes severe swelling in the tonsils, fever, sore throat, rash, and fatigue. • Strep throat: Streptococcus, a bacterium, infects the tonsils and throat. Fever and neck pain often accompany the sore throat. • Enlarged (hypertrophic) tonsils: Large tonsils reduce the size of the airway, making snoring or sleep apnea more likely. • Tonsilloliths (tonsil stones): Tonsil stones, or tonsilloliths, are formed when this trapped debris hardens, or calcifies.

39. Tonsillectomy & Adenoidectomy • http://www.entusa.com/tonsils_adenoid_surgery.htm • Note: not for the queasy

40. Thymus • This organ programs T cells and functions at its highest in youth • The thymus is a small organ in your upper chest, under your breastbone. • Before birth and during childhood, the thymus helps the body make a type of white blood cell. • These cells help protect you from infections.