Exam 4 - Lecture 20 Flashcards
in order to cause disease, a pathogen must do what two things?
- get inside the host (overcome host surface barriers)
- survive inside the host (overcome resistance by the host)
what is immunity?
ability of a host to resist a particular disease or infection
true or false: the adaptive immune system is non-specific.
false; the adaptive immune system is specific, the innate is non-specific.
describe the following for the innate immune system:
- speed
- specificity
- memory
- speed: fast response, components always present
- specificity: not very, effective towards a wide variety of infectious agents
- memory: none
describe the following for the adaptive immune system:
- speed
- specificity
- memory
- 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
match the following:
- innate immunity
- adaptive immunity
a. first line of defense
b. second line of defense
c. third line of defense
1a
1b
2c
what make up the first line of defense in the immune system?
- barriers
- skin
- mucous membranes
what make up the second line of defense in the immune system?
- antimicrobial peptides
- complement
- cytokines
- inflammation
- phagocytes
- NK cells
what make up the third line of defense in the immune system?
- antibodies
- lymphocytes
- B cells
- T cells
mucous membranes are made up of a variety of antimicrobial substances like:
- lysozymes
- RNAse enzymes
- lactoferrin
what do lysozymes do?
hydrolyze the bond connecting sugars in peptidoglycan
what do RNAse enzymes do?
degrade RNA
what does lactoferrin do? why?
sequesters iron so that the bacteria potentially living in the mucous membrane do not have the nutrients it wants to grow
what are the components of the innate immune system?
- chemical/humoral (antimicrobial peptides, complement, cytokines)
- cellular (phagocytes, natural killer cells)
what are AMPs?
small antimicrobial peptides that usually function by inserting into the membrane and are abundant in external mucosa like the mouth
what is the complement system?
complex system composed of over 30 proteins that either directly kill or opsonize bacteria
what are MACs?
membrane attack complexes
how does the complement system kill bacteria?
MACs made of 5 different complement proteins come together to kill
what are the 5 complement proteins in an MAC?
C5b, C6, C7, C8, C9
what is opsonization?
a process in which the surface of a microbe is coated with a substance called an opsonin
opsonized microbes are much _______________________ and __________ by phagocytic cells.
more easily recognized and destroyed
what are the two types of opsonins?
- complement protein C3b
- antibodies
what are cytokines?
- soluble proteins or glycoproteins
- signaling molecules released by one cell population that act as intracellular mediators
what are the classes of cytokines?
- interleukins (IL)
- interferons (IF)
- tumor necrosis factors (TNF)
- colony stimulating factors (CSF)
what is a primary function of cytokines? what is the purpose?
inflammation to recruit components of the immune system
what are the two mechanisms for microbial recognition by a phagocyte?
- opsonin-dependent (opsonic) recognition
- opsonin-independent (nonopsonic) recognition
true or false: phagocytosis is greatly decreased by opsonization.
false; it is greatly increased
what is the mechanism for opsonin-independent pathogen recognition?
PAMPs unique to the pathogen (not the host) are detected
what are PAMPs?
pathogen-associated molecular patterns
PAMPs are recognized by _______ on phagocytic cells.
PRRs (pattern recognition receptors)
one class of PRRs important in fighting infection are:
toll-like receptors (TLRs)
when a phagosome fuses with a lysosome, they become a:
phagolysosome
what is phagocytosis?
activity that results in the killing and breakdown (digestion) of a microbe
the cells of the immune system are called:
leukocytes (white blood cells)
what are the phagocytic cells of the immune system?
- monocytes
- macrophages
- dendritic cells
- neutrophils
NK cells release cytotoxic enzymes called:
granzymes
what are NK cells?
- natural killer cells
- small population of lymphocytes
- kills cells infected with pathogen
- plays important role in innate community
normal cells express a membrane protein called _____________. if a cell has lost this protein, an NK cell will do what?
- class major histocompatibility complex (MHC class I)
- infected cells lose this protein and NK cells release granzymes and kill them when they find them
what is the ADCC method of infected cell killing by NK cells?
- antibody-dependent cell-mediated cytotoxicity
- antibodies bind to antigens on infected host cells, NK cells bind the antibodies and kill the infected cells
what are antigens?
substances that elicit an immune response
what are epitopes?
antigenic determinant sites that react with the specific antibody or T cell receptor
this will probably be on the exam: what cells are antibodies created by?
B lymphocytes
true or false: antibodies are specific.
why yes they are
what is another name for an antibody?
immunoglobulin (Ig)
true or false: antibodies are large glycoproteins.
true
how many polypeptide chains are present in immunoglobulin structure? what are they?
- four polypeptides chains
- 2 identical heavy chains
- 2 identical light chains
how are the heavy and light chains of immunoglobulin connected?
disulfide bonds
light and heavy chains consist of what two regions?
constant and variable regions
the four chains of an antibody are organized in a ____ shape
Y
the stem of an antibody is the _________ fragment (___) and the tips of the Y are the _________ regions (________ __________ ___________ ____)
- constant fragment, Fc
- variable, antigen binding sites, Fab
Fc facilitates binding to:
- cells of the immune system (trigger phagocytosis; opsonization)
- complement system (activates it)
the primary antibody response is:
slow
the concentration of antibody is serum is called:
antibody titer
what are the consequences of antibody-antigen binding?
- opsonization
- agglutination
- complement
- neutralization
- precipitation
what are lymphocytes?
- major cells of the immune system
what are B lymphocyte characteristics?
- mature in bone marrow
- circulates in the blood
- primary role: produce antibodies
- T cells help in the process
what are T lymphocyte characteristics?
- 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
what do T helper cells (TH) do?
assist in antibody production
what do cytotoxic T lymphocytes (CTLs) do?
ability to kill infected cells
