The Lymphatic System

1. The Lymphatic System http://www.faqs.org/health/Body-by-Design-V1/The-Lymphatic-System.html

2. The Lymphatic System • The body is constantly in contact with bacteria, fungi, and viruses (all considered pathogens) • The body has two defense systems for foreign materials

3. Types of Defense • Non-Specific Defense • First & Second Line of Defense • Doesn’t care what the pathogen is – your body will be defended!

4. Non-Specific Defense • Non-Specific Defense Mechanisms Include… • Skin: mechanical barrier, acidic skin secretions can also defend • Mucous Membranes: Mucus and nasal hairs trap microorganisms; Cilia move mucus out of body; Gastric juice, saliva, and tears have enzymes that destroy microorganisms • Skin and Mucous Membranes are the first line of defense against pathogens • Cellular & Chemical Defense: Second line of defense; includes…

5. Non-Specific Defense • Phagocytes: • Cell that engulfs a foreign particle, enclosing it in a vacuole; destroyed with enzymatic contents of lysosomes

6. Non-Specific Defense • Examples of phagocytes include macrophages (in body tissues, developed from monocyte WBC), and neutrophils (WBC)

7. Macrophage engulfing E-Coli

8. Non-Specific Defense • Natural Killer Cells: • Defensive cells that can kill cancer cells and virus-infected body cells • Release chemicals to destroy invader’s cell membrane and nucleus

10. Non-Specific Defense • Inflammatory Response: • Non-specific response triggered whenever body tissues are injured

13. Non-Specific Defense • Benefits of inflammatory response include: • Preventing the spread of damaging agents to nearby tissues • Disposes of cell debris and pathogens • Sets the stage for repair

14. Non-Specific Defense • 4 Signs of Inflammatory Response: • Redness – due to dilation of blood vessels in area, bringing more clotting proteins/ oxygen/nutrients to the area • Heat – due to dilation of blood vessels in area, helps increase metabolic rate of cells • Swelling – due to plasma (lymph) leaking from blood stream into tissue spaces • Pain – pain receptors activated by plasma leaking

16. Non-Specific Defense • All of the above symptoms are due to the inflammatory chemicals (including histamine and kinins) that are released when cells are damaged

17. Non-Specific Defense • Fever: response to invading pathogens • Hypothalamus will reset internal temperature based on presence of pyrogens (chemicals secreted by WBC exposed to foreign substances) • Fever inhibits the release of iron and zinc from liver and spleen needed by bacteria • Fever also increases the speed of tissue repair, but if fever gets too high, it can screw up enzymes and proteins

18. Specific Defense • Specific Defense • Third line of defense • AKA immune system • Plans defense based on specific type of pathogen/antigen (The antigen is a marker on the pathogen!) • Must first have an initial exposure before it can protect the body against the pathogen • Involves the Lymph Vessels/Nodes and Lymphoid Organs (Tonsils, Thymus, Spleen, and Peyer’s Patches)

19. Specific Defense • 2 Types of Response: Humoral and Cell-Mediated

20. Specific Defense • 3 important aspects of immune response: • Antigen specific – recognizes and acts against particular foreign substances • Systemic – not restricted to the initial infection site • Has memory – recognizes and mounts a stronger attack on previously encountered pathogens

21. Specific Defense • Antigens: any substance capable of exciting our immune system and provoking an immune response • A foreign signal on the outside of a pathogen! • Examples of common pathogens/antigens • Foreign proteins (ex: blood typing) • Pollen grains • Microorganisms (bacteria, fungi, virus) • Side Note: Our immune cells do not attack our own proteins, but our cells in another person’s body can trigger an immune response because they are foreign (think: organ transplants, blood donation)

23. Immune System Review • Types of cells involved • Lymphocytes (WBC): two types… • B Cells: help with humoral defense, produce antibodies • T Cells: help with cell-mediated defense, do not produce antibodies

24. Specific Defense • Both types of lymphocytes originate from red bone marrow • What determines if it will be a B or T cell is where in the body it becomes immunocompetent (capable of responding to a specific antigen) • T Cells: lymphocytes migrating to thymus • B Cells: lymphocytes develop in bone marrow

26. Specific Defense • Our genes determine what specific foreign substances our immune system will be able to recognize and resist – they only become “activated” once exposed to the antigen

27. FYI: Because of the structure of human DNA (deoxyribonucleic acid; the genetic material determining the makeup of all cells), humans are not subject to certain diseases that dogs and other animals are, and vice-versa. For example, humans cannot contract distemper; however, dogs and cats can. Conversely, humans can suffer from measles; dogs and cats cannot. The genetic makeup of human cells (and of animal and plant cells, also) makes it impossible for certain pathogens to infect and reproduce in those cells.

28. Specific Defense • After becoming immunocompetent, both T and B cells migrate to the lymph nodes and spleen, but can be found throughout lymphatic vessels

29. Specific Defenses • Macrophages: • Arise from monocytes (WBC) formed in the bone marrow • Job is to engulf foreign particles (part of non-specific defense) and present fragments of these antigens on their surface (so T Cells can recognize them and become activated, helping out specific defense!)

30. Humoral Defense • Making the Antibodies • B Cells with specific receptors bind to a specific antigen • …which causes the B Cell to undergo “clonal selection” – a whole bunch of clones are made!

31. Humoral Defense • Most of the clones will become “plasma cells”, which are responsible for producing specific antibodies! • A few of the clones will become “memory cells”, which will be ready to bind with the antigen if it should come around again

33. Humoral Defense • Antibodies • Soluble proteins secreted by B cells (plasma cells) • Carried in blood plasma • Usually has a T or Y shape formed by amino acid chains • Capable of binding specifically to an antigen

34. Humoral Defense • When antibodies attach to antigens, it can have different effects…

35. Humoral Defense • Complement Fixation: antibody will join with a “complement protein” on the invader; which will allow holes on the invader surface; will result in cell lysis (bursting of cell)

36. Humoral Defense • Neutralization: surrounds antigen to mask its effects

37. Humoral Defense • Agglutination: clumping of antigens; will allow macrophages to easily catch and engulf invaders

39. Cell Mediated Defense • Begins with macrophages destroying an antigen • Macrophage will then put fragments of the destroyed antigen on the outside • T Cells will recognize the antigen being presented by the macrophage and bind with the antigen (Antigen Presentation) • After binding, T Cell clones form, but different classes of cells are produced

40. Cell Mediated Defense • Cytotoxic T Cell: “killer” cells, specialize in killing virus-infected, cancer, and foreign cells, often by inserting toxic chemicals, causing the pathogen cell to “blow up” Note: basically does the same thing as a Natural Killer Cell, but does it to a specific pathogen!

41. http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter24/animation__cytotoxic_t-cell_activity_against_target_cells__quiz_2_.htmlhttp://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter24/animation__cytotoxic_t-cell_activity_against_target_cells__quiz_2_.html

43. Cell Mediated Defense • Helper T Cell: “regulator/conductor” cells, encourages cloning of B cells, stimulates Cytotoxic T Cells to grow and divide, enhances eating capabilities of macrophages

44. Cell Mediated Defense • Supressor T Cell: helps to stop immune response once an antigen has been inactivated or destroyed

45. http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter24/animation__the_immune_response.htmlhttp://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter24/animation__the_immune_response.html

46. Viruses • Not considered “living” because has no cytoplasm or organelles • Needs a living host cell to survive • Will take over host cell to replicate • Virus infections cannot be treated with antibiotics • Some can be prevented with vaccines

47. Viruses • Common Cold • Varicella - Chicken Pox – rarely fatal • Variola – Smallpox – often fatal – but now eliminated thanks to vaccinations! • Influenza – MANY different strains! • Human Papillomavirus – HPV – can lead to warts, cervical cancer, and some other genital cancers • Rotavirus – leading cause of diarrhea among infants and young children

48. Smallpox Chicken Pox

49. Viruses • Mumps – swelling of salivary glands, and testicular swelling • Measles – can lead to diarrhea, pneumonia, encephalitis, and eye infections • Rubella – rash • Poliomyelitis – in less than 1% of polio cases, virus enters the CNS, destroying motor neurons, leading to muscle weakness and paralysis; highly contagious • Rabies – causes encephalitis; extremely fatal • HIV

50. Measles Mumps Rubella MMR Vaccination protects against all three!