Chapter 52-The Immune System

Question 1

Immonolgical tolerance

Answer 1

the bodys defenses must learn to recognize our own healthy normal cells, tissues and organs not not respond to these

Question 2

Human pathogenic microorganisms

Answer 2

microorganisms that can cause disease in humans

-includes many viruses, some prokaryotes, and a few fungi, protozoa and worms

Question 3

strict obligate pathogeninc

Answer 3

microorganism that when present in/on the body in sufficient dose in proper place will cause the disease associated with in most people (ie ebola virus, influenza virus, etc)

Question 4

Infectious disease

Answer 4

a disease whose ultimate cause is due to a pathogenic microorganism

Question 5

steps of pathogenesis

Answer 5

1. exposure-pathogen must come from somehwere and arrive at a certain place in your body in sufficient dose
2. Microorganism must move from portal of entry to place where it can replicate well (invasion)
3. Microbial replication-when the microbe replicates the signs and symptoms of a disease first become noticeable and also when the bodys defenses become most apparent
4. the bodys defenses are fully activated-object to kill the pathogen and prevent it from spreading
5. exit of pathogen from host

Question 6

Non specific defenses

Answer 6

present at birth and do not improve much with age

• general recognition of invading pathogens
• first response to exposure

Question 7

Non specific defenses (types)

Answer 7

1. Barriers-at body surfaces (portals of entry)
   - -try to prevent pathogen from getting from the portal to site of replication
   - -barriers=physical (our own cells and microbial flora), mechanical (tearing, blinking, sweating, urination), and biochemical (salt in sweat, stomach acid, fatty acids in sebum)

Question 8

Specific defenses

Answer 8

adaptive or acquired immunity
-develops over time
-second line defenses, slower response but highly specific
-involves cells and antibodys
responsible for immunity

Question 9

Skin

Answer 9

barrier

• largest organ of body
• provides nearly impenetrable barrier

Question 10

3 other routes of infection

Answer 10

digestive, respiratory and urogenital tracts-barriers

-all three lined by epithelial cells, secrete mucus which traps microbes

Question 11

Non specific (innate) defenses (internal)

Answer 11

• Phagocytic cells-neutrophils, macrophages, and dendritic cells
• inflamation
• fever
• complement proteins
• interferon
• various proteins
• coughing, sneezing
• vomiting, diarrhea
• natural killer cells

Question 12

3 kinds of defending leukocytes (innate immunity)

Answer 12

1, macrophages-kill microorganisms through phagocytosis

2. neutrophils-most abundant circulating leukocyte
   - also use phgocytosis
3. natural killer cells
   - do not attack invading cells directly
   - induce apoptosis in target cell

Question 13

Inflammatory response

Answer 13

marshalls bodys defenses at site of infection

• injured cells release chemical alarms
• cause nearby blood vessels to dilate and increase in permeability
• promote phagocyte accumulation

Question 14

fever

Answer 14

elevated body temperature

• macrophages release interleukin-1
• causes hypothalamus to raise body temp
• promotes activity of phagocytes, while impeding microbial growth
• however, high fevers can denature proteins-dangerous

Question 15

complement system

Answer 15

consists of about 30 different proteins that circulate in the blood in an inactive form

• becomes activated
• proteins aggregate to form a membrane attach complex (MAC) on surface of pathogen
• pathogen swells and bursts

Question 16

antigens

Answer 16

molecule that provokes a specific immune response

-all molecules are antigens, but classified differently

Question 17

self antigen

Answer 17

personas normal molecules in/on his cells

Question 18

non-self antigens

Answer 18

molecules from anything else-microorganisms, cat hair, pollen, etc.

Question 19

altered self antigens

Answer 19

tumors

Question 20

epitopes

Answer 20

[art of antigen that is recognized as foreign by the specific defenses

Question 21

epitopes are recognized by what

Answer 21

specific receptor proteins on the surface of the cells of the adaptive immune response

• B lymphocytes
• T lymphocytes

Question 22

Specific defenses are characterized by what?

Answer 22

1. specificity of recognition of epitopes on antigens on microorganisms
2. wide diversity of antigens can be specifically recognized by different B and T lymphocytes
3. Memory, where the immune system can respond more quickly to an antigen it has already encountered
4. ability to distinguish self-antigens from non-self and altered self

Question 23

The specific immune response

Answer 23

1. recognition of foreign epitope on pathogen by B lymphocyte and/or T lymphocyte
2. activation of those lymphocytes that confer protection against the pathogen
3. effect:
   - B lymphocytes become plasma cells and secrete antibodyy
   - cytotoxic T cells attack intracellularly infected host cells and cancer cells

Question 24

Humoral adaptive immunity

Answer 24

B lymphocytes or B cells with the help of other cells respond to antigens by secreting antibodies that bind to pathogens antigens

Question 25

Cell-Mediated adaptive immunity

Answer 25

cytotoxic T lymphocytes or T cells with the help of other cells directly attack infected host cells or cancer cells -if memory B and T cells form, immunity results

Question 26

Immune recognition

Answer 26

receptors on lymphocytes bind specifically to epitopes on antigens on microorganisms

Question 27

Active immunity

Answer 27

results form activation of an individuals own lymphocytes | -pathogen infection or vaccination

Question 28

passive immunity

Answer 28

results from obtaining another individuals antibodies - transfer of maternal antibodies across placenta - antiserum with antibodies

Question 29

Organs of the immune system

Answer 29

Primary Lymphoid organs - bone marrow and thymus, locations where the B and t cells mature before being sent to secondary lymphoid tissues - Secondary lymphoid organs-where lymphocytes come in contact with antigens - -lymph nodes, spleen, and mucosal associated lymphoid tissue (MALT)

Question 30

Primary Lymphoid organs

Answer 30

Bone marrow is site of B cell maturation -thymus is site of T cell maturation recognize epitopes only if they are combined with major histocompatibility complex (MHC) peptides

Question 31

Secondary Lymphoid Organs

Answer 31

- Locations of these organs promote the filtering of antigens that enter any part of an individual's body - mature but naive B and T cells become activated in the lymph nodes - spleen is site of immune responses to antigens found mainly in the blood - MALT tissue include the tonsils and appendix

Question 32

T lymphocutes

Answer 32

2 types - cytotoxic T cells-kills infected host cels and cancer cells - Helper T cells-helps B cells and cytotoxic T cells become activated

Question 33

How cytotoxic T cells work

Answer 33

- recognize foreign peptides bound to self-MHC class 1 proteins - clonal expansion and differentiate into activated cells and memory cells - activated cells induce apoptosis in cells wtih same specificity as first cell and results in death of infected cell

Question 34

How helper T cells work

Answer 34

respond to antigen that is taken up by an antigen presenting cell - antigen complexed with MHC class 2 proteins - activated T helper cells give rise to effector cells and memory cells

Question 35

Humoral immunity begins..

Answer 35

begins when naive B cells in secondary lymph organs meet antigens -B cells are activated when their surface lgs bind to a specific epitope on an antigen Activation results in clonal expansion and differentiation into plasma and memory cells -plasma cells produce soluble antibodies against the same epitope

Question 36

5 classes of immunoglobulins

Answer 36

1. lgM-first antibody secreted, promotes agglutination reaction and activates complemet 2. lgD-present only on surfaces of B cells, serves as antigen receptor 3. lgG-major antibody secreted during the secondary response, neutralizes antigens and promots their phagocytosis 4. lgA-most abundant antibody 5. lgE-binds to mast cells and basophils, allergens bind to it and it triggers allergic reaction

Question 37

Primary immune response

Answer 37

first encounter with a foreign anitgen - only few B or T cells can recognize antigen - clonal expansion occurs, memory cells

Question 38

Secondary immune response

Answer 38

secondary ecounter | -large clone of memory cells that can recognize the antigen

Question 39

Allergy

Answer 39

refers to a greatly heightened response to a foreign antigen, or allergen (not on a pathogen) - most common type is known as immediate hypersensitivity - results from excessive lgE production

Question 40

Blood type

Answer 40

Determined by antigens found on the surface of red blood cells -ABO blood types-types A, B AB, and O Immune system is tolerant of own RBC antigens --ex. people with type A blood make antibodies against the type B antigen

Question 41

autoimmune diseases

Answer 41

caused by the failure of immune tolerance - result in activation of autoreactive T cells, and production of autoantibodies by B cells - cause inflamation and organ damage

Question 42

How do some pathogens evade the immune system

Answer 42

alter their surface antigens to avoid detection