1. The Immune System
Chapter 40

2. Agents of Disease
The human body provides a suitable environment for many microorganisms: it is moist, warm and full of nutrients.
Not all microorganisms are harmful; some are beneficial.
Bacteria living in the intestines aid in digestion.
Microorganisms that cause disease are called pathogens.
Agents of disease include viruses, bacteria, protists, worms, fungi, arachnids and insects.

4. Infectiously Cute Plush Microbes!

5. Pathogens and Disease Section 40-1 Pathogen Types Disease
Agent That Causes Disease
Method of Transmission
Common cold
Rhinovirus
Two types (A, B), plus subtypes
Varicella
Paramyxovirus
Mycobacterium tuberculosis
Neisseria meningitidis
Vibrio cholerae
Clostridium tetani
Trypanosoma
Plasmodium
Entamoeba histolytica
Schistosoma
Taenia saginata
Imperfect fungi
Airborne; direct contact with infected person
Airborne; droplet infection; direct contact with infected person
Droplets in air; direct contact with secretions of infected person
Droplets in air; contaminated milk and dairy products
Direct contact with a carrier
Contaminated drinking water
Contaminated wound; usually puncture wound
Spread by tsetse fly
Spread by Anopheles mosquitoes
Freshwater streams and rice paddies
Contaminated meat
Contact with infected person
Exchange of hats, combs, or athletic head gear with infected person
Viruses
Influenza
Chickenpox
Measles
Bacteria
Tuberculosis
Meningitis
Cholera
Tetanus
Protists
African sleeping sickness
Malaria
Amoebic dysentery
Worms
Schistosomiasis
Beef tapeworm
Fungi
Athlete’s foot
Ringworm

6. Infectious Disease
Diseases caused by pathogens that can be transmitted from one individual to another are called infectious diseases.
Methods of transmittal include:
Sneezing

8. Infectious Disease
Diseases caused by pathogens that can be transmitted from one individual to another are called infectious diseases.
Methods of transmittal include:
Sneezing
Coughing

10. Infectious Disease
Diseases caused by pathogens that can be transmitted from one individual to another are called infectious diseases.
Methods of transmittal include:
coughing
Sneezing
Contaminated food or water

11. Urban migration and dense populations offer the perfect environment for the spread of microbial pathogens.

12. Infectious Disease
Diseases caused by pathogens that can be transmitted from one individual to another are called infectious diseases.
Methods of transmittal include:
coughing
Sneezing
Contaminated food or water
Physical contact

14. Infectious Disease
Diseases caused by pathogens that can be transmitted from one individual to another are called infectious diseases.
Methods of transmittal include:
coughing
Sneezing
Contaminated food or water
Physical contact
Infected animals

16. Fighting Disease….

17. Antibiotics
Sir Alexander Fleming discovered the first antibiotic, penicillin, by mistake.

18. Antibiotics Antibiotics work by destroying the cell wall of bacteria.
They are specific to certain bacteria.
They are ineffective against viruses.
Overuse of antibiotics has led to resistant strains of bacteria.

19. Methicillin-resistant Staphylococcus aureus

20. Vaccines
A vaccine is a weakened or dead form of a pathogen or its toxin.
Vaccines stimulate the immune system to protect the body against future invasions by the pathogen.
The first vaccine was developed by Edward Jenner against the Small Pox virus.

21. The first vaccination: Edward Jenner used pus from the hand of a dairy maid in 1796
Image: © Bettmann/Corbis

22. The Immune System First Line of Defense Physical and chemical barriers
Skin
Secretions
Stomach acid

23. The Immune System Second Line of Defense
Inflammatory response – phagocytes
Redness, swelling, heat, fever
Interferon

24. Video 1

25. The Immune System Third Line of Defense
The immune response - lymphocytes
Antigens (foreign substances) that get past the first and second lines of defense will trigger the production of antibodies by white blood cells.
These antibodies are specific for the antigen that caused their formation.
Antibodies bind to antigens disabling them.

26. Structure of an Antibody
Section 40-2
Antigen- binding sites
Antigen
Antibody

27. Immunity
Once activated, the immune system white blood cells “remember” the antigens.
Future invasions by the antigen are destroyed immediately by circulating antibodies.

28. Immune Response Interval between exposures Antibody Concentration
Section 40-2
Immune Response
Interval between exposures
Antibody Concentration
First exposure
Second exposure
Time

29. Passive Immunity
“Borrowed” immunity - the immune system is not activated.
Temporary.
Antibodies from another source are taken to combat the disease (antibiotics).
Eventually the antibodies are recognized as foreign and destroyed.

30. Active Immunity
The immune system is activated and produces antibodies.
Lasts a lifetime.
Vaccines stimulate active immunity.

31. Rejection
Our tissues contain their own antigens (proteins capable of generating antibodies).
Our immune system recognizes these antigens as belonging to ourselves, and does not produce antibodies against them.
When a tissue or organ is transplanted, the recipient’s immune system will not recognize it as “self” and will manufactures antibodies to destroy it.
This is known as rejection.
Drugs are administered to suppress the immune system and lessen this effect.

32. Immune System Disorders

33. Immune System Disorders
Allergies (a.k.a. immune system gone haywire)
The immune system decides certain antigens are deadly …(cat fur, dust, mold, pollen, bee stings, poison ivy) and an inflammatory response is triggered against these allergens.
Histamines released by certain cells cause the classic symptoms: watery itchy eyes, runny nose, sneezing, wheezing, coughing, rash….. fun, fun, fun…..

34. Poison Ivy

35. Immune System Disorders
Asthma
An allergic reaction causing the air passageways to narrow therefore restricting breathing.
Can be triggered by respiratory infections, exercise, emotional stress, cold air, dust, pollen, dander, and some medications.
The tendency towards asthma is inherited.

37. Immune System Disorders
Autoimmune diseases
The immune system fails to recognize itself and mistakenly identifies parts of the body as foreign and attacks.
Type 1 diabetes
Rheumatoid arthritis
Multiple sclerosis

38. Multiple Sclerosis

39. Immune System Disorders
AIDS Acquired Immune Deficiency Syndrome
A virus, HIV, destroys key white blood cells involved in the immune response.
A person with AIDS does not have a functional immune system.
Previous immunity to diseases no longer is effective.