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Immune System Review for Test
Germ Theory - What causes infectious diseases?
 Microorganisms
What pathogens have we identified as agents of disease?
 Viruses
 Bacteria
 Fungi
 Parasites
NON-SPECIFIC DEFENSE
Include skin, tears, and other secretions; the inflammatory response, and fever
First Line:
 Skin
 Saliva, mucus, tears (all contain lysozymes that break down bacterial cell wall)
 Stomach acid
Second Line:
 Inflammatory response (mast cells & histamines)
 Fever – slows down growth of pathogens
SPECIFIC DEFENSE
Antigens: foreign substance that can stimulate an immune response.
Antibodies: tag the antigen for destruction
Lymphocytes:
1. B-Cells – produced in bone marrow, discover antigens in body fluids, produce antibodies
2. T-Cells – mature in the thymus, must encounter an infected cell
Immune System in Action
 B-cells and T-cells, continually on the search for antigens
 B-cells look for antigens in body fluids
 T-cells look for infected cells
Immune System works in 2 Ways…
1. Humoral immunity – blood and lymph
 White blood cells called B lymphocytes (B-cells) make antibodies that attack pathogens in
the blood
2. Cell-mediated Immunity
 White blood cells called T lymphocytes (T-cells) find and destroy abnormal or infected cells
ACTIVE VS. PASSIVE IMMUNITY
 Active Immunity
 Body produces its own antibodies in response to an antigen
 Natural (had the disease) or artificial (vaccine)
 Long lasting immunity – disease rarely recurs
 Passive Immunity
 Person is given antibodies obtained from blood of another person or animal
 Temporary – few weeks of protection
IMMUNE SYSTEM DISORDERS
1. Allergies
 Over reaction to harmless antigens. Antigens bind to mast cells, which release
histamines and cause increased blood flow and allergy symptoms. May take antihistamines to stop this reaction.
2. Asthma
 Narrowing of air passages; can be caused by allergies
3. Autoimmune
 Immune system attacks its own cells (self).

Examples: Type 1 diabetes, rheumatoid arthritis, lups, MS
HIV & AIDS
 1970’s – doctors notice rare infections
 HIV attaches to helper T-cells
 Inside T-cells, makes more copies of the HIV
 Infects more helper T-cells
 Helper T-cells coordinate the immune response and alert other immune cells to invaders.
Without these, the immune system fails to respond to invaders
 T-cells eventually die and when down to 1/6th normal T-cell levels, person has AIDS
 Transmission: infected blood, semen, vaginal secretion, breast milk
KNOW ALL OF THESE CELLS, WHAT THEY DO, AND THEIR ORDER IN THE IMMUNE RESPONSE
Order in Immune
Response
Cell
Function
1st
Macrophage
First to respond to a new pathogen. Uses psuedopods to engulf and digest the pathogen
2nd
Helper T Cell
Coordinates and alerts other immune cells to the pathogen
3rd
B Cell
Makes antibodies to tag the new pathogen
4th
Killer Cell
Releases toxic chemicals that destroy pathogens
5th
Cytotoxic T Cell
Destroys infected or damaged cells
6th
Memory Cell
Speeds up immune response the next time the body is exposed to the pathogen
Study Guide Answers:
1. List the 4 main types of pathogens.
 Virus, bacteria, parasite, fungi
2. What is the best way to protect humans against most viral diseases?
 Vaccination
3. How might a fever be beneficial to a person who is sick?
 It slows down the growth of the pathogen.
4. What is the relationship between antibodies and antigens?
 Antigens (short for antibody generators) are foreign substances that can trigger an
immune response by Antibodies, which tag the antigens for destruction by the immune
cells
5. What are the roles of helper T cells and cytotoxic T cells?
 Helper T-cells cooridnate and alert other immune cells to pathogens
 Cytotoxic T cells destroy infected or damaged cells
6. What is the specific action of HIV that makes the body unable to cope with other infections?
 Because it infects and destroys helper T-cells, it essentially eliminates the body’s
coordinatio\n and alert system for pathogens. As a result, the immune system does not
funtion and the body becomes easily infected with pathogens that a healthy immune
system could have fought off. When an individual has 1/6 th the normal amount of
helper T-cells, they are considered to have AIDS (acquired immune deficiency syndrome).
7. What are the main cells of the immune system and what they do and how they interact with
each other? See the chart
8. What is an autoimmune disease and what are at least two examples?
 When the immune system fails to recognize self from non-self and attacks it’s own
systems. Examples include Type 1 diabetes, Lupus, MS
9. What is the difference between active and passive immunity?
 Active – the body produces its own antibodies in response to exposure to a pathogen
(this includes your body making antibodies as a result of vaccination. Long lasting,
chance of disease recuring is low.
 Passive – you receive antibodies from another person’s blood or from an animal source.
Does not last long (several weeks). Chance of recurance is high.
10. What do allergies have to do with the immune system? Explain what a histamine is.
 Allergies are an over-reaction to antigens that should be harmless. Mast cells produce
histamines – compounds that cause contraction of the muscle and dilation of the
capilarries – resulting in swelling.
11. What is the structure of an antibody? – See diagram, looks like a Y.