KEY CONCEPT 31.1 Germs cause many diseases in humans.

1. KEY CONCEPT 31.1Germs cause many diseases in humans.

2. Germ theory states that microscopic particles cause certain diseases. • proposed by Louis Pasteur • led to rapid advances in understanding disease

3. Koch’s postulates support the theory • - Pathogen must be present in every case disease is found • - Pathogen must be isolated and cultured • - Healthy animal must be injected • - Pathogen must be collected, isolated, and identical to original • Disease-causing agents are called pathogens.

4. There are different types of pathogens. 1. Bacteria are single-celled organisms. • cause illness by destroying cells • release toxic chemicals

5. 2. Viruses are genetic material surrounded by a protein coat. • force host cells to make more viruses • very small

6. take nutrients from host cells • occur in warm and damp places 3. Fungi can be multicellular or single-celled.

7. use host cells to complete their life cycles • take nutrients from host cell 4. Protozoa are single-celled organisms.

8. grow and feed on a host • possibly kill the host 5. Parasites are multicellular organisms.

9. Different pathogen cause common infectious diseases.

10. Pathogens can enter the body in different ways. • Pathogens can be transferred by direct or indirect contact. • Indirect contact does not require touching an infected individual. • touching an infected surface • breathing in infected air

11. Vectors carry a pathogen and transmit it into healthy cells. • Direct contact requires touching an infected individual. Includes: • kissing • sexual intercourse • hand shaking tick

12. Summary 31.1 • What conditions must be met before a specific pathogen is proved to cause a disease? • Name the five general types of pathogens. Provide an example of each. • Name three ways a pathogen can be spread. • Contrast a virus with a bacteria. How do they differ in ways that they affect cells in the body? • What is a vector? Provide 2 examples.

13. Ch 31.2 KEY CONCEPTThe immune systems consists of organs, cells, and molecules that fight infections.

14. Many body systems protect you from pathogens. • The immune system is the body system that fights off infection and pathogens. • Many other tissues and systems help the immune system. • Skin • Mucous membranes trap pathogens • The circulatory system transports immune cells.

15. Cells and proteins fight the body’s infections. • White blood cells attack infections inside the body. • Phagocytes engulf and destroy pathogens. • T cells destroy infected cells. • B cells produce antibodies.

16. antibody pathogens • Three types of proteins fight off invading pathogens. • Complement proteins weaken pathogen membranes. • Antibodies make pathogens ineffective. • Interferons prevent viruses from infecting healthy cells.

17. Immunity prevents a person from getting sick from a pathogen. • In all immunity, pathogens are destroyed before you get sick. • Passive immunity occurs withoutan immune response. • mother’s milk • genetics • Active immunity occurs after aspecific immune response • Which would vaccines be?

18. Summary 31.2 • How does the immune system work with other body systems to prevent and fight disease? • How do phagocytes help to fight infection? • Name the two types of immunities. Which requires white blood cells? Explain. • How do complement proteins differ from antibodies? • If a person had a disease that prevented lymphocytes from maturing, how would the immune system’s response to infection change?

19. extracellular space capillary wall white blood cell 31.3 Key Concept: Many body systems work to produce nonspecific responses. • Nonspecific responses are the same for every pathogen. • In inflammation, blood vessels become leaky. • white blood cells movetoward infection anddamaged tissue • characterized by swelling, redness, and pain

20. Low fevers stimulate white blood cells to mature. • In fever, body temperature increases. • High fevers can cause seizure, brain damage, and even death.

21. antigens virus Cells of the immune system produce specific responses. • Specific immune responses begin with the detection of antigens. • Antigens are surface proteins on pathogens. • Each pathogen has a different antigen.

22. pathogen antigens antigens T cell receptors activated T cells memory T cells • Cellular immunity uses T cells to destroy infected body cells. • There are two specific immune responses.

23. B cell pathogen antibodies T cell memory B cells activated B cells • Humoral immunity uses B cells to produce antibodies. • There are two specific immune responses.

24. B cell T cell • Both responses produce memory cells. • specialized T and B cells • provide acquired (active) immunity

25. The immune system rejects foreign tissues. • Tissue rejection occurs in organ or tissue transplants. • immune system detects protein markers on the donor tissue • makes antibodies against the donor’s tissue

26. Summary 31.3 • How does inflammation help the immune system to fight pathogens? • What is the main difference between cellular and humoral immunity? • What is tissue rejection, and why does it occur? • Why might it be beneficial for a person to get blood or tissue donated from a relative instead of a non-related donor? • What are the differences between a specific and nonspecific immune response?

27. 31.4 Many methods are used to control pathogens. • Antibiotics and antiseptics cause pathogens to burst. • Antibiotics inside body • Antiseptic outside

28. Vaccines artificially produce acquired immunity. • Vaccines also control pathogens and disease. • prevent illness • contain the antigen of a weakened pathogen

29. Antigens in a vaccinetrigger an immune response, and memory B cells are made. 1 memory B cells 2 A memory B cell isstimulated when the real pathogen binds to it. The B cell quickly activates and makes antibodies that fight the pathogens before you get sick. 3 Vaccination provides immunity. • stimulates a specific immune response • causes memory cells to be produced • allows immune system to respond quickly to infection • has such a fast response, a person will not get sick

30. 31.5 Allergies occur when the immune system responds to harmless antigens. • Allergies are caused by allergens. • Allergens: antigens that cause an allergic reaction. • Allergens cause inflammation responses. • Examples: foods, airborne, chemicals

31. Allergens can cause anaphylaxis. • Anaphylaxis is an extreme inflammation response. • Blood vessels and airways become too porous. • Can cause death

32. In autoimmune diseases, white blood cells attack the body’s healthy cells. • Autoimmune diseases are failures of the immune system. • White blood cells cannot recognize healthy cells. • Tissues fail because of attack.

33. Ch 31.6 • Leukemia is cancer of the bone marrow. • characterized by immature white blood cells • causes weakened immune system • Leads to opportunistic infections

34. HIV targets the immune system. • The human immunodeficiency virus (HIV) is a retrovirus. • RNA • HIV causes host cell DNA to copy its RNA, then incorporate it into the DNA of the cell • Lysogenic until triggered to lytic

35. deadT cell T cell activatedB cell antibody HIV • HIV infection leads to AIDS (Acquired Immune Deficiency Syndrome). • HIV reproduces in and destroys T cells. • The body cannot replace T cells fast enough. • T cells cannot help in immune responses.

36. Summary Review Questions • What is the difference between specific and nonspecific response? • Summarize the steps the immune system takes when it your body is vaccinated. • Under what conditions is an antigen called an allergen? • What is an autoimmune disease and why might it be considered a failure of the immune system? • How do AIDS and HIV differ? • Which cells are affected by HIV and Leukemia? And what parts of the immune system do the influence?