1. Immunity and Infection
Chapter 17

2. The Chain of Infection Pathogen: Disease causing microorganism
Reservoir: Natural environment of the pathogen
Portal of exit: How does the pathogen exit reservoir and cause infection
Means of transmission
Direct transmission
Indirect transmission
Vectors: Carrier of the pathogen from one host to another
Portals of entry
Penetration of the skin
Inhalation through mouth or nose
Ingestion
New host 2 2

3. Figure 17.1 The chain of infection

4. The Immune System
Definition: A functional system of diverse molecules, cells and lymphoid tissues that protect the body from foreign substances
The Immune System provides immunity or resistance to disease
Immunity is Provided In Two Ways:
The Innate or Non Specific Defense System
Adaptive or Specific Defense System

5. Innate (nonspecifice) Defense
Characteristics
Responds to an invasion in minutes
Response is the same for all invaders
No memory
Uses two types of barriers:
Surface
Skin
Mucous membranes
Internal
Phagocytes (Ex. macrophages)
Fever
NK cells
Inflammation

6. Adaptive (specific) Defense
Characteristics
Extremely specific
Systemic
Has memory
Can distinguish self from non-self
Two arms in Adaptive Defense:
Antibody-mediated immunity
Provided by antibodies found in blood
Cell-mediated immunity
Provided by white blood cells (WBC’s)

7. Antigens (Ag)
Definition: Any foreign substance that causes an immune response
Usually large molecules that are not normally present in the body

8. Cells of the Adaptive Defense System
Three important types:
First Type: B lymphocytes
Function: Produce antibodies
Responsible for Antibody-Mediated Immunity
Three important types:
First Type:
B lymphocytes
Produce antibodies
Are responsible for the antibody-mediated response

9. Cells of the Adaptive Defense System
Second Type :T lymphocytes
Do not produce antibodies
Responsible for Cell Mediated Immunity
Three populations of T lymphocytes:
T helper
T killer
T suppressor
Three important types:
Second Type
T lymphocytes
Do not produce antibodies
Are the cell mediated branch
Three populations of T lymphocytes
T helper
T killer
T suppressor

10. Cells of the Adaptive Defense System
Third Type: Antigen presenting cells (APCs)
Function: Engulf & digest Ags. and present the fragments to T helpers
Presentation to T helpers activates them so that they can activate T killer and B cells
Three important types:
Third Type:
Antigen presenting cells (APCs)
Engulf antigens and present the fragments to T lymphocytes
Presentation activates T and B lymphocytes

11. The Immune Response Four phases of the Immune Response:
First Phase (Recognition)
Antigens invade the body and replicate
APCs recognize invaders, engulf and digest them
APCs present fragments to T helper cells, activating them with Interleukins
First phase = incubation period; may not have symptoms, but may be contagious

12. The Immune Response Four phases of the Immune Response:
Second Phase (Proliferation)
Activated T helper cells multiply rapidly
T helper cells release cytokines to trigger production of T killers & B lymphocytes

13. The Immune Response Four phases of the Immune Response:
Third Phase (Elimination)
T killer cells attack foreign cells and infected cells of the body (puncture membranes of target cells)
B lymphocytes produce Abs
Antibodies work by binding antigens, thereby marking them for destruction/removal by macrophages
Four phases of the Immune Response:
Third Phase
T killer cells attack foreign cells and infected cells of the body (puncture membranes of target cells)
Foreign cells are recognized by Ags on their surface
B lymphocytes produce Abs
Abs bind antigen-bearing targets, marking them for destruction by macrophages

14. The Immune Response Four phases of the Immune Response:
Fourth Phase (Slowdown)
Immune response slows
Memory B and T cells are formed
Homeostasis is restored by T suppressor cells
Dead cells, pathogens, etc. are scavenged by WBCs and filtered out by 1) liver
2) spleen 3) kidneys

15. 1. 4. 3.
B cell
T helper
T Killer 2.

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The Immune Response
Chapter seventeen
© 2008 McGraw-Hill Companies. All Rights Reserved.

17. Immunization Basis of immunization Vaccine Immune system has memory
Immune system retains strength against pathogen
Vaccine
Defined as a weakened/killed version of microbe that is administered to stimulate an immune response

18. Immunization Types of Immunity
Active Immunity – a person produces their own antibodies to the microorganism
Passive Immunity - Injection of antibodies produced by other human beings or animals to a person exposed to a disease

19. Types of Pathogens & Diseases they Cause
Bacteria- meningitis, pneumonia, strep throat, etc.
Viruses – HIV, HPV, Herpes, etc.
Fungi- causes yeast infections, etc.
Protozoa- causes malaria, etc.
Parasitic worms- tapeworms, hookworms, pinworms, etc.
Chapter seventeen
© 2008 McGraw-Hill Companies. All Rights Reserved.

20. Viruses Nonliving matter
Viruses are like parasites – they hijack enzymes and necessary machinery from its host in order to reproduce
Host cell function is disrupted and host cell becomes a factory for manufacturing more viruses
Different viruses affect different types of cells
This determines seriousness of illness
Ex. HPV affects the cervix in females

21. Types of Pathogens Bacteria Single celled organisms
Bacteria can be harmful and helpful bacteria
Helpful bacteria in GI tract produce vitamins (vitamin K)

22. The Lymphatic System Network of vessels and organs Lymphatic vessels
Pick up excess fluid, proteins, etc. from blood stream
Lymph nodes
Act as filters to remove pathogens
Spleen
Contains cells to destroy old RBCs
Tonsils
Contain lymphocytes
Thymus
T-cells mature here

23. Typical Life Cycle of a Virus

24. HIV and AIDS Human Immunodeficiency (Virus) The virus that causes AIDS
Acquired Immune Deficiency Syndrome (AIDS)
Late stages of HIV infection
Body is no longer able to fight off infection
HIV + individuals suffer from bacterial infections, cancer, TB, etc.
AIDS does not kill you, opportunistic infections do.

25. The Human Immunodeficiency Virus
HIV Structure
Viral capsid
Contains RNA & enzymes that aid in the infection process
HIV is a Retrovirus
Converts its RNA into DNA
This viral DNA is inserted into host DNA

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Life Cycle of HIV
Chapter seventeen
© 2008 McGraw-Hill Companies. All Rights Reserved.

27. Contracting HIV You CAN get HIV from a person who is infected through:
Sexual contact with an infected person.
Most risky sexual behavior?
Sharing needles for with someone who is infected
Contaminated Blood Products - Donated blood and blood products; Before 1985 donated blood was not tested
Birth - Babies born to HIV-infected women may become infected; or through breast-feeding after birth.

28. HIV and AIDS Diagnosis/Treatment
ELISA (Blood Test)
Detects Antibodies against HIV
If positive, a CD4+ count is taken to determine severity
Treatment
No known cure
HAART
Taken every day for the rest of one’s life

29. Autoimmune Diseases Autoimmune diseases
Definition: When the bodies immune system attacks its own tissues
Ex’s. Rheumatoid arthritis, Systemic lupus erythmatosus (Lupus)