1. The Lymphatic System
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 Lymphocytes (WBC): two types…
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

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
hill.com/sites/ /student_view0/chapter24/animation__th e_immune_response.html