Chapter 40

1. Chapter 40 The Immune System & Disease

2. §40-1 Infectious Disease • What is a pathogen? • Any disease causing agent.

3. Could cigarette smoke be a pathogen? • Yup. • Name some others…

4. Long long ago… • It was thought that disease was caused by evil spirits or curses.

5. Now we know that infectious diseases are caused by mircoorganisms (germs) Germ Theory of Disease Louis Pasteur, Robert Koch How does Lyme Disease tie into all of this? Alan Steere (1975) put two and two together and realized that Lyme Disease followed a tick bite so the tick must be the carrier.

6. Koch’s postulates – Rules to identify specific pathogens • The pathogen should be found in the body of a sick organism but not in a healthy one. • The pathogen must be isolated and grown in the laboratory in pure culture • When cultured pathogens are placed in a new host, they should cause the same disease that infect the original host. • The injected pathogen should be isolated from the second host and should be identical to the original pathogen.

7. If you were a pathogen, where would you want to reside? • The human body – why? • Temperature is ideal for growth. • Lots of water available. • Many nutrients.

8. How do pathogens cause disease? • Destroy cells • Release toxins • Block blood flow • Remove nutrients (worms, especially) Trypanosoma – African Sleeping Sickness (protest)

9. Agents of Disease • Viruses – attach to surface, inject their own DNA or RNA and take over the host cell. • Example: Avian flu (bird flu)

10. Agents of disease • Bacteria – break down tissue and/or release toxins. • Example: Listeria (a type of food poisoning)

11. Agents of disease • Protists – Cause of the single most damaging infectious disease afflicting humans (malaria)

12. Agents of disease • Worms – Ewwww. • Example: Schistosoma – infect workers in rice fields, enter through flesh, cause abdominal pain and fever. Female can lay eggs that cause obstructions.

13. Agents of disease • Fungi – mostly harmless, some deadly • Example: aminitaphalloides (death cap mushroom). Best to get your mushrooms from the supermarket  • Hmmm…is this a pathogen or just a poison?

14. Agents of disease • Fungal pathogen – Candida albicans • Causes “thrush” or vaginal yeast infections

15. Spread of diseases Infected Animals • vectors – carry the disease How to Prevent? Stay away or use repellant. Physical Contact • through the air •sexual contact How to Prevent? Cover your mouth when you cough, wash your hands Contaminated Food & Water • food poisoning How to Prevent? Be careful in food preparation

16. Fighting infectious disease • Antibiotics – discovered by Alexander Fleming (accidentally) • Knew that this “thing” had antibiotic properties and when bacteria were near it, they didn’t grow. • Turned out to be a fungus (penicillin) • Antibiotics don’t work on viral infections • Antivirals • Inhibit development of the pathogen (they don’t destroy it). • Used for specific viral infections

17. §40-2 The Immune system • What is immunity? • Fighting infection through the production of cells that inactivate foreign substances or cells. • Two Types: • Nonspecific Defenses • Specific Defenses

18. Nonspecific Defenses • First line of defense • Keep pathogens out of the body. • Skin is most important nonspecific defense. • Just think about what happens when you get a cut…redness, swelling are all signs your body is fighting an infection.

19. First Line of Defense (con’t) • Lysozyme • Breaks down bacterial cell walls • Oil and sweat glands • produce an acidic environment that discourages bacteria. • Mucus • Helps to trap pathogens • Cilia • Trap pathogens • Digestive enzymes • mwahahahahaha

20. Second Line of defense • Inflammatory response • Nonspecific defense reaction to tissue damage • Millions of WBC produced (phagocytes engulf and destroy bacteria) • Blood vessels near wound expand so cells can enter infected tissue

21. Second Line of Defense • Chemicals released which increase temperature (fever) • Pathogens can only survive in a narrow temperature range • Increased temperature  increased heart rate so WBC move to site more quickly • Interferons • Groups of proteins which “interfere” with the growth of the virus.

22. Specific defenses • Immune response • Attacks specific disease-causing agents • Antigen • The “thing” that triggers the immune response. • Two types of lymphocytes • B lymphocytes (B cells) – provide humoral immunity (to antigens in body fluids) • T lymphocytes (T cells) – provide cell-mediated immunity (to abnormal cells an pathogens inside living cells).

23. Humoral immunity 1. Pathogen invades body. Antigens are recognized by B cells as a “foreigner”. 2. B Cells grow and divide rapidly, produce plasma cells and more memory B cells. 3. Plasma cells release antibodies (proteins that recognize and bind to antigens). 4. Antibodies are carried to bloodstream to attack the pathogen. 5. As infection dies out, plasma cells die and stop producing antibodies. 6. Memory B cells remain capable of producing antibodies should the same pathogen infect the organism. 7. Memory B cells produce plasma cells to produce antibodies should the pathogen strike again.

24. B Cell Antigens Antigens bind to B Cell B cells grow and divide rapidly Some B cells turn into memory B cells Some B cells turn into plasma cells

25. Memory B cells produce more plasma cells, more antibodies & more memory B cells upon another exposure to antigen Plasma cells produce antibodies which are released into the bloodstream Many years later… Antibodies attack antigen immediately

26. Structure of an antibody • Antigen binding sites located at both ends of the “Y” • Different amino acids affect shape of sites so they are specific to each antigen. • Differently shaped binding sites allow different antibodies for each antigen. • Healthy humans can produce about 100 million different types of antibodies. • Did you know…the human body produces cancerous cells every day but the immune system fights them off. Yay!!

27. Cell-mediated immunity • When antigens get inside living cells, antibodies alone cannot destroy them • Examples: Cancer, some viruses, fungi, protists

28. How cell-mediated immunity works

29. transplants • When someone else’s organ (heart, liver, cornea, lung, kidney, etc.) is implanted in your body, your body sees it as foreign and begins the immune response. • This will cause “rejection” and will often kill the recipient. • To prevent this doctors • Try to match the organ donor tissue type to the recipient • Keep the recipient on immune-suppressing drugs to inhibit the immune response • What issues might this cause in the future?

30. Vaccines – Edward Jenner • English physician 200 years ago • Knew that “cowpox” (a mild form of smallpox) was acquired by milkmaids and then they became immune to smallpox. • Took fluid from the sores of a cowpox patient and injected it into a farm boy (Jamie Phipps). • Jamie developed cowpox (are we surprised?) • Two months later, Jenner injected Jamie with smallpox (a lawsuit in the making) • Jamie did not contract the disease…REALLY BIG SURPRISE!

31. Acquired immunity • Vaccines – stimulate the immune response to create millions of plasma cells ready to produce specific antibodies. • This is a type of active immunitywhich appears after exposure to an antigen.

32. Acquired immunity • Passive immunity – occurs when antibodies produced by other animals against a pathogen are injected into the bloodstream. • Antibodies are effective but the response is short-lived. • Can develop deliberately or naturally. • Examples: antibodies produced by the mother are passed on to the fetus in utero, travel vaccinations can also provide passive immunity.

33. §40-3 immune system disorders • Allergies • Autoimmune Diseases • Immunodeficiency Diseases

34. Allergies – the process Allergy-causing agents enter the body and attach themselves to mast cells Mast cells activate the inflammatory response and release histamines Antihistaminescounteract these effects Increase blood and fluid flow to surrounding area (swelling) Increase mucus production (sneezing, watery eyes, runny nose)

35. Some people have allergies to cats…

36. asthma • A chronic respiratory disease caused by narrowing air passageways. • Leading cause of serious illness among children. • Can lead to permanent damage or destruction of lung tissue if not treated early enough. • Can be triggered by respiratory infection, exercise, stress, medications, cold air, pollen, dust, tobacco smoke, pollution, molds and pet dander. • No cure but can usually identify triggers and treat symptoms.

37. Autoimmune diseases • Occur when the body attacks its own cells. • Examples: • Type 1 Diabetes • Rheumatoid arthritis, multiple sclerosis • Treatments – usually involve meds which suppress the immune response but this causes other issues.

38. aids • Acquired Immune Deficiency Syndrome • A viral infection that destroys helper T cells. Normal immune response breaks down. • Victims contract unusual diseases which are normally prevented by a healthy immune system (Pneumocysticcarinii, Kaposi’s scarcoma, fungal infections).

39. The virus that causes aids • Human Immunodeficiency Virus (HIV) • A retrovirus (what does that mean?) • Good at escaping the body’s immune system • Destroys body’s defenses so victim is immuno-compromised. • Attacks helper T cells by entering them and uses host machinery to make it’s own DNA and RNA. Some viral DNA is integrated into host’s DNA. • Virus will leave cell and enter new cell and the cycle continues. • As virus progresses, T cell count goes down…this is the indicator that AIDS is progressing in the body.

40. Transmission of HIV • Can only be transmitted through exchange of bodily fluids. • Sexual intercourse • Shared needles • Contact with blood of an infected person • Mother to child during birth or breast-feeding

41. Preventing HIV infection • The only no-risk sexual behavior is abstinence • Wear condoms • Avoid IV drug use • Wear latex gloves when handling blood or blood products

42. Cure for AIDS? • AIDS evolvs rapidly so once a “cure” is established, the virus has moved on. • Currently there are drugs to help control the virus so people with AIDS are living longer. • Roughly 20 million people have died of AIDS worldwide so far.

43. §40-4 the environment & Your health

44. Air quality • Risk factor – anything that increases the chance of disease or injury. • Environmental factors: • Air Quality – considers gases present as well as particulates in the air. • Carbon monoxide – binds to hemoglobin in your blood so your blood can’t carry oxygen. This could be hazardous to your health. • Ozone – a highly reactive form of oxygen. Produced by vehicle and factory emissions. Can cause asthma, bronchitis, emphysema. • Airborne Particulates – include smoke, asbestos, solvents, certain types of paint.

45. Water quality • Bacteria , viruses , chemical pollutants can be found in water that isn’t processed properly.

46. bioterrorism • The intentional use of biological agents to disable or kill individuals. • Can involve the intentional release of infectious agents • Viruses (smallpox) • Bacteria (anthrax) • Toxic compounds (toxins) from living organisms

47. cancer • Occurs when cells multiply uncontrollably. • Caused by mutations in genes that control cell growth. • How does it happen? • Uncontrolled cell growth leads to formation of tumors • These tumors can block blood flow and nerve connections between tissues, absorb needed nutrients.

48. causes • Cancer is caused by defects in the genes that regulate cell growth & division. • Chemical compounds (carcinogens) • i.e. cigarette smoke…contains some of the most powerful carcinogens known. • Cigarettes are responsible for nearly half the cancers that occur in the U.S. • Radiation • Causes most forms of skin cancer • Genetics – some people are predisposed to certain types of cancer • i.e. the BRCA gene (for a certain type of breast cancer)

49. Maintaining health • Diet • Exercise • Rest • Abstain from Harmful Activities • Regular Checkups