Immune System and Disease. Chapter 31

Transcription

1 Immune System and Disease Chapter 31

2 31.1 PATHOGENS AND HUMAN ILLNESS

3 Key Concept Germs cause many diseases in humans

4 Microogranisms (microscopic particles) cause certain diseases proposed by Louis Pasteur led to rapid advances in understanding disease Germ Theory

5 Koch s Postulates Support the germ theory Disease-causing agents are called pathogens

6 Pathogens Many different types Bacteria are singlecelled organisms. cause illness by destroying cells release toxic chemicals

7 Pathogens Viruses: genetic material surrounded by a protein coat force host cells to make more viruses very small

8 Fungi Can be multicellular or single-celled take nutrients from host cells occur in warm and damp places

9 Protozoa Single-celled organisms use host cells to complete their life cycles take nutrients from host cell

10 Parasites Multicellular organisms grow and feed on a host possibly kill the host

11 Pathogens Different pathogens cause common infectious diseases

12 How Pathogens Enter the Body Can be transferred by direct or indirect contact Indirect: does not require touching an infected individual touching an infected surface breathing in infected air

13 How Pathogens Enter the Body Vectors: carry a pathogen and transmit it into healthy cells Direct: requires touching an infected individual: kissing sexual intercourse hand shaking tick

14 31.2 IMMUNE SYSTEM

15 Key Concept The immune system consists of organs, cells, and molecules that fight infections

16 The Immune System The body system that fights off infection and pathogens Many other tissues and systems help the immune system Skin: a physical barrier to infection. Mucous membranes: trap pathogens entering the body Circulatory system: transports immune cells

17 Immune Cells White blood cells (WBC s) attack infections inside the body phagocytes engulf and destroy pathogens T cells destroy infected cells B cells produce antibodies

18 Immune Proteins Fight off invading pathogens Complement proteins weaken pathogen membranes Antibodies make pathogens ineffective Interferons prevent viruses from infecting healthy cells

19 Immunity Prevents a person from getting sick pathogens are destroyed before sickness Passive immunity (occurs without an immune response): mother s milk genetics Active immunity (occurs with an immune response)

20 31.3 IMMUNE RESPONSES

21 Key Concept The immune system has many responses to pathogens and foreign cells

22 Nonspecific Responses Are the same for every pathogen Ex: inflammation blood vessels become leaky white blood cells move toward infection and damaged tissue characterized by swelling, redness, and pain

23 Nonspecific Responses Fever blood temperature increases low fevers stimulate white blood cells to mature high fevers can cause seizure, brain damage, and even death

24 Specific Responses Caused by immune cells Begin with antigen detection antigens are surface proteins on pathogens each pathogen has a different antigen

25 Specific Responses (1 of 2) Cellular Immunity uses T cells to destroy infected body cells

26 Specific Responses (2 of 2) Humoral Immunity uses B cells to produce antibodies

27 Memory Cells Produced by both Cellular and Humoral Immunity specialized T and B cells provide acquired (active) immunity

28 Foreign Tissues Tissue rejection occurs in organ or tissue transplants Tissue rejection is the result of an immune respons immune system detects protein markers on the donor tissue makes antibodies against the donor s tissue

29 31.4 IMMUNITY AND TECHNOLOGY

30 Key Concept Living in a clean environment and building immunity help keep a person healthy

31 Technology Many methods to control pathogens Antibiotics and antiseptics cause pathogens to burst

32 Technology Antiseptics: kill pathogens outside the body do not target specific pathogens ex: vinegar, soap Antibiotics: kill pathogens inside the body target one specific bacterium or fungus not effective against viruses

33 Antibiotic Resistance Can cause medicines to become ineffective some bacteria in a population have genes that make them immune to antibiotics these bacteria spread the gene, making the antibiotics useless

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35 Vaccines Artificially produce acquired immunity Control pathogens and disease given to prevent illness contain the antigen of a weakened pathogen

36 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

37 31.6 DISEASES THAT WEAKEN THE IMMUNE SYSTEM

38 Key Concept When the immune system is weakened, the body cannot fight off disease

39 Leukemia Cancer of the bone marrow characterized by immature white blood cells causes weakened immune system

40 Leads to opportunistic infections occurs because white blood cells cannot fight infections if immune system were healthy, would fight these infections Leukemia

41 HIV Human immunodeficiency virus (HIV) is a retrovirus targets the immune system attacks and weakens the immune system is transmitted by mixing infected blood with a bodily fluid

42 HIV Leads to AIDS HIV reproduces in and destroys T cells the body cannot replace T cells fast enough T cells cannot help in immune responses

43 AIDS Acquired immune deficiency syndrome several opportunistic infections very low amount of T cells