Exam 4 - Lecture 20

Question 1

in order to cause disease, a pathogen must do what two things?

Answer 1

• get inside the host (overcome host surface barriers)
• survive inside the host (overcome resistance by the host)

Question 2

what is immunity?

Answer 2

ability of a host to resist a particular disease or infection

Question 3

true or false: the adaptive immune system is non-specific.

Answer 3

false; the adaptive immune system is specific, the innate is non-specific.

Question 4

describe the following for the innate immune system:

• speed
• specificity
• memory

Answer 4

• speed: fast response, components always present
• specificity: not very, effective towards a wide variety of infectious agents
• memory: none

Question 5

describe the following for the adaptive immune system:

• speed
• specificity
• memory

Answer 5

• speed: slow response, components must be made
• specificity: very, active against a narrow range of infectious agents
• memory: retains memory of invading pathogen, response is enhanced uponrepreated contact with the pathogen

Question 6

match the following:

1. innate immunity
2. adaptive immunity

a. first line of defense
b. second line of defense
c. third line of defense

Answer 6

1a
1b
2c

Question 7

what make up the first line of defense in the immune system?

Answer 7

• barriers
• skin
• mucous membranes

Question 8

what make up the second line of defense in the immune system?

Answer 8

• antimicrobial peptides
• complement
• cytokines
• inflammation
• phagocytes
• NK cells

Question 9

what make up the third line of defense in the immune system?

Answer 9

• antibodies
• lymphocytes
• B cells
• T cells

Question 10

mucous membranes are made up of a variety of antimicrobial substances like:

Answer 10

• lysozymes
• RNAse enzymes
• lactoferrin

Question 11

what do lysozymes do?

Answer 11

hydrolyze the bond connecting sugars in peptidoglycan

Question 12

what do RNAse enzymes do?

Answer 12

degrade RNA

Question 13

what does lactoferrin do? why?

Answer 13

sequesters iron so that the bacteria potentially living in the mucous membrane do not have the nutrients it wants to grow

Question 14

what are the components of the innate immune system?

Answer 14

• chemical/humoral (antimicrobial peptides, complement, cytokines)
• cellular (phagocytes, natural killer cells)

Question 15

what are AMPs?

Answer 15

small antimicrobial peptides that usually function by inserting into the membrane and are abundant in external mucosa like the mouth

Question 16

what is the complement system?

Answer 16

complex system composed of over 30 proteins that either directly kill or opsonize bacteria

Question 17

what are MACs?

Answer 17

membrane attack complexes

Question 18

how does the complement system kill bacteria?

Answer 18

MACs made of 5 different complement proteins come together to kill

Question 19

what are the 5 complement proteins in an MAC?

Answer 19

C5b, C6, C7, C8, C9

Question 20

what is opsonization?

Answer 20

a process in which the surface of a microbe is coated with a substance called an opsonin

Question 21

opsonized microbes are much _______________________ and __________ by phagocytic cells.

Answer 21

more easily recognized and destroyed

Question 22

what are the two types of opsonins?

Answer 22

• complement protein C3b
• antibodies

Question 23

what are cytokines?

Answer 23

• soluble proteins or glycoproteins
• signaling molecules released by one cell population that act as intracellular mediators

Question 24

what are the classes of cytokines?

Answer 24

• interleukins (IL)
• interferons (IF)
• tumor necrosis factors (TNF)
• colony stimulating factors (CSF)

Question 25

what is a primary function of cytokines? what is the purpose?

Answer 25

inflammation to recruit components of the immune system

Question 26

what are the two mechanisms for microbial recognition by a phagocyte?

Answer 26

- opsonin-dependent (opsonic) recognition - opsonin-independent (nonopsonic) recognition

Question 27

true or false: phagocytosis is greatly decreased by opsonization.

Answer 27

false; it is greatly increased

Question 28

what is the mechanism for opsonin-independent pathogen recognition?

Answer 28

PAMPs unique to the pathogen (not the host) are detected

Question 29

what are PAMPs?

Answer 29

pathogen-associated molecular patterns

Question 30

PAMPs are recognized by _______ on phagocytic cells.

Answer 30

PRRs (pattern recognition receptors)

Question 31

one class of PRRs important in fighting infection are:

Answer 31

toll-like receptors (TLRs)

Question 32

when a phagosome fuses with a lysosome, they become a:

Answer 32

phagolysosome

Question 33

what is phagocytosis?

Answer 33

activity that results in the killing and breakdown (digestion) of a microbe

Question 34

the cells of the immune system are called:

Answer 34

leukocytes (white blood cells)

Question 35

what are the phagocytic cells of the immune system?

Answer 35

- monocytes - macrophages - dendritic cells - neutrophils

Question 36

NK cells release cytotoxic enzymes called:

Answer 36

granzymes

Question 37

what are NK cells?

Answer 37

- natural killer cells - small population of lymphocytes - kills cells infected with pathogen - plays important role in innate community

Question 38

normal cells express a membrane protein called _____________. if a cell has lost this protein, an NK cell will do what?

Answer 38

- class major histocompatibility complex (MHC class I) - infected cells lose this protein and NK cells release granzymes and kill them when they find them

Question 39

what is the ADCC method of infected cell killing by NK cells?

Answer 39

- antibody-dependent cell-mediated cytotoxicity - antibodies bind to antigens on infected host cells, NK cells bind the antibodies and kill the infected cells

Question 40

what are antigens?

Answer 40

substances that elicit an immune response

Question 41

what are epitopes?

Answer 41

antigenic determinant sites that react with the specific antibody or T cell receptor

Question 42

this will probably be on the exam: what cells are antibodies created by?

Answer 42

B lymphocytes

Question 43

true or false: antibodies are specific.

Answer 43

why yes they are

Question 44

what is another name for an antibody?

Answer 44

immunoglobulin (Ig)

Question 45

true or false: antibodies are large glycoproteins.

Answer 45

true

Question 46

how many polypeptide chains are present in immunoglobulin structure? what are they?

Answer 46

- four polypeptides chains - 2 identical heavy chains - 2 identical light chains

Question 47

how are the heavy and light chains of immunoglobulin connected?

Answer 47

disulfide bonds

Question 48

light and heavy chains consist of what two regions?

Answer 48

constant and variable regions

Question 49

the four chains of an antibody are organized in a ____ shape

Answer 49

Y

Question 50

the stem of an antibody is the _________ fragment (___) and the tips of the Y are the _________ regions (________ __________ ___________ ____)

Answer 50

- constant fragment, Fc - variable, antigen binding sites, Fab

Question 51

Fc facilitates binding to:

Answer 51

- cells of the immune system (trigger phagocytosis; opsonization) - complement system (activates it)

Question 52

the primary antibody response is:

Answer 52

slow

Question 53

the concentration of antibody is serum is called:

Answer 53

antibody titer

Question 54

what are the consequences of antibody-antigen binding?

Answer 54

- opsonization - agglutination - complement - neutralization - precipitation

Question 55

what are lymphocytes?

Answer 55

- major cells of the immune system

Question 56

what are B lymphocyte characteristics?

Answer 56

- mature in bone marrow - circulates in the blood - primary role: produce antibodies - T cells help in the process

Question 57

what are T lymphocyte characteristics?

Answer 57

- mature in the thymus - can remain in the thymus, circulate in the blood, reside in the lymphoid tissue - activated T cells can differentiate into T helper cells or cytotoxic T lymphocytes

Question 58

what do T helper cells (TH) do?

Answer 58

assist in antibody production

Question 59

what do cytotoxic T lymphocytes (CTLs) do?

Answer 59

ability to kill infected cells