Exam 3 Flashcards
1
Q
What is the function of a cytokine receptor, and where are they found?
What is a cytokine?
A
Found on the surface of all leukocytes; they bind to cytokines.
Cytokines are molecules that leukocytes use to
communicate with one another.
2
Q
Where do you find MCH I cells?
A
Every cell in the body with a nucleus (not red blood cells).
3
Q
What three cells contain MHC II molecules? What do they do?
A
B-cells, dendritic cells, and macrophages.
They present antigen to a helper t-cell
4
Q
True or false:
Generally speaking, antigens are molecules that are normally not found in the body.
A
true
5
Q
What’s the difference between an exogenous antigen and an endogenous
antigen?
A
Exogenous antigens are molecules produced by foreign cells that stimulate an immune response. Endogenous antigens are molecules produced by cells in the human body that stimulate an immune response (ex. cancer cells + cells infected by viruses)
6
Q
Dendritic cells are usually one of the first immune cells to encounter a pathogen. Why is this?
A
They are found in the common areas that pathogens enter the body (skin, nose, lung, intestines)
7
Q
Dendritic cells play a big role in the immune system’s response to exogenous antigens because dendritic cells can directly activate _____.
A
T-cells
8
Q
Which of the following molecules are normally found on dendritic cells? Select any/all correct answers.
CD4
CD8
MHC I
MHC II
Toll-like receptor
A
MHC I
MHC II
Toll-like receptor
9
Q
Suppose that a dendritic cell has encountered a foreign, exogenous, antigen. Explain/outline how this then results in the activation of a helper T-cell.
A
The toll-like receptor on the dendritic cell will bind to a foreign molecule, and the dendritic cell will produce a co-stimmulatory molecule that it exports to the outside of the cell. It then takes in the foreign molecule that has been bound to the TLR, chops it up, and attaches it to the MHC II to export outside of the cell. This dendritic cell presents the co-stimmulatory molecule and the bits of the chopped up foreign molecule to the helper t-cell. The helper t-cell receptor binds to the MHC II carrying the foreign molecule, and CD4 is there to help strengthen this bond. The co-stimmulatory molecule receptor on the helper t-cell binds to the co-stimmulatory molecule produced by the dendritic cell. The helper t-cell then activates.
10
Q
One of the things that makes helper T-cells different from cytotoxic T-cells is that helper T-cells have __________ molecules on their surface.
A
CD4
11
Q
Once a dendritic cell activates a helper T-cell, it divides to form a type of cell called an _______ helper T-cell.
A
effector
12
Q
Explain/outline how an effector helper T-cell causes a B-cell to become activated.
A
b-cells recognize free floating exogenous antigens via b-cell receptor, and they take them in and chop them up. Once chopped, the b-cell loads a piece onto the MHC II molecule, exports these molecules to the outside of the b-cell, and presents it to the effector t-cell helper. This t-cell receptor binds to the MHC II molecule and the molecule it is presenting, and the CD4 molecule of the helper t-cell strengthens this bond. The b-cell also has a CD40, and if the effector helper t-cell recognizes the molecule being presented as foreign it will produce a CD40 ligand, which the CD40 can recognize, as well as cytokines which will are recognized by the cytokine receptors on the b-cell. The b-cell is then activated.
13
Q
Once a B-cell is activated, it produces clones of itself. Some of these clones become ________ cells, while the other clones become ________ cells.
A
memory b-cells and plasma cells
14
Q
How are memory B-cells different from other B-cells?
A
They contain more cytokine receptors than b-cells.
They stay in the blood/ lymph after an infection has been fought off so that they can be better equipped to deal with the same antigen if it sees it again in the future. When they do spot the antigen again they differentiate into strong plasma cells
15
Q
The function of plasma cells is to produce and release ________.
A
antibodies/immunoglobulins
16
Q
List and describe 5 things that antibodies can do to help eliminate pathogens.
A
after antibodies bind to pathogens they can:
- prevent pathogens from binding to our cells (neutralization)
- cause compliment proteins to become activated
- activate other cells of the immune system to attack the bacterium (ADCC - antibody dependent cell-mediated cytotoxicity) (ex. natural killer cell sticking to bacterial cell and lysing it)
- agglutination: when many antigens are bound together preventing spread of bacterium and for more efficient phagocytocis.
- opsonization: when coating an antigen with a protein (ex. an antibody) increases the chances its chance of being phagocytized.
17
Q
Natural killer (NK) cells can attack bacteria that have antibodies on them because NK cells have a particular type of receptor. What’s the name of this receptor?
A
FC receptor
18
Q
Once a macrophage has taken in a pathogen, the macrophage can then activate a ______
A
helper t-cell
19
Q
List 4 examples of leukocytes that can be activated by helper T-cells:
A
b-cells, macrophages, natural killer cells, and cytotoxic t-cell
20
Q
TH1’s are helper t-cells that release cytokines that activate _____ cells and _____ cells
A
natural killer cells and cytotoxic t-cells
21
Q
TH2’s are helper t-cells that release cytokines that activate _____ cells.
A
b-cells
22
Q
What are the differences between a T-dependent antigen and a T-independent antigen?
A
T-dependent antigens are small and made of proteins. They can activate a b-cell only if there is an activated helper t-cell nearby.
T-independent antigens are very large and made from lipids and carbs (sugars). B-cells don’t require an active/helper t-cell to activate them because the antigen bound to the b-cell is bound to multiple b-cell receptors and TLR simultaneously.
23
Q
T-independent antigens produce clones that become _____ cells and not _____. This is due to the lack of cytokine involvement.
A
plasma, memory b-cells
24
Q
True or false:
It is only possible for molecules located on a bacterial cell to be recognized by, and activate, the immune system.
A
false; molecules located within a bacterial cell be recognized and activate the immune system too. This can only happen when the bacterial cell is ingested by a macrophage and then chopped up, exposing the interior molecules.
25
The type of T-cell that can directly recognize and respond to an endogenous
antigen is a _____.
cytotoxin t-cell
26
True or false:
Viruses can potentially infect any cell in the body.
True
27
Which cells can potentially become tumor cells?
any cells in the body
28
MHC I molecules present…:
- proteins made by bacterial cells.
- “abnormal” proteins (i.e. viral proteins and tumor proteins) made inside our own cells.
- proteins that are normally made inside our own cells.
“abnormal” proteins (i.e. viral proteins and tumor proteins) made inside our own cells
AND
proteins that are normally made inside our own cells.
29
Suppose that an MHC I molecule presents a normal protein (i.e. one that is normally made inside one of our healthy cells) to a cytotoxic T-cell. What would the cytotoxic T-cell do in response?
disregard it
30
Suppose that an MHC I molecule presents an abnormal protein (e.g. a viral protein or a tumor protein) to a cytotoxic T-cell. What would the cytotoxic T-cell do in response?
kill the entire cell
31
Cytotoxic T-cells kill abnormal cells by:
causing the abnormal cell to “shrivel up” (shrink) so that a macrophage can ingest it.
32
Cytotoxic T-cells have _______ molecules on their surface.
CD8
33
After infecting a cell, some viruses are able to stop the cell from making MHC I molecules. This is beneficial to the virus because it prevents the virus from being attacked by _______ cells. However, we do have a type of leukocyte that can
attack the virus in this situation. This leukocyte is a _______ cell.
cytotoxic t-cells
natural killer cell
34
Based on its appearance, explain why “heavy” is an appropriate description for the heavy chain.
It is the larger chain within the antibody; the piece that exists within the constant and variable regions
35
Antigens attach to the ______ region of an antibody molecule.
variable (upper)
36
Complement proteins attach to the ______ region of an antibody molecule.
complement (lower)
37
describe the function of IgA:
Most abundant type of immunoglobulin found on mucous membranes and in secretions (e.g. saliva and tears)
38
describe the function of IgD:
Plays a role in helping B-cells mature
39
describe the functions of IgG: (edit)
Capable of initiating the classical pathway of complement activation
Immunoglobulin that can circulate the longest before becoming degraded.
Immunoglobulin that can most readily be transferred from mother to fetus (via the placenta)
Immunoglobulin that’s most effective at agglutinating antigens
Most abundant type of immunoglobulin found in the serum
40
describe the functions of IgM:
Capable of initiating the classical pathway of complement activation
Immunoglobulin that’s most effective at agglutinating antigens
Type of immunoglobulin that’s produced first when the immune system first encounters an antigen
41
describe the functions of IgM?
Capable of initiating the classical pathway of complement activation
Immunoglobulin that’s most effective at agglutinating antigens
Type of immunoglobulin that’s produced first when the immune system first encounters an antigen
42
What antibodies have a single Y shape structure?
IgE, IgD, IgG
43
what antibody has a double mirrored Y shaped structure?
IgA
44
What antobody has a pentagonal Y shaped structure?
IgM
45
Before patrolling the blood/lymph, B-cells must first develop in the __________.
red bone marrow
46
B-cells and T-cells that are still developing in the bone marrow are called __________ B-cells.
immature
47
Basically, 2 things happen to developing B-cells in the bone marrow: (1) immature B-cells that __________ are generated, and (2) immature B-cells that __________ are eliminated.
recognize different antigens, recognize self antigens
48
True of false:
Every B-cell in a person’s body recognizes the exact same epitope.
False
49
The Y shaped molecule on a b-cell is called _______.
an antibody molecule; immunoglobulin
50
Which part of the antibody molecule binds to epitopes?
the variable portion (top)
51
The variable region of an antibody molecule is divided into three parts. Starting from the top of the variable region moving down towards the constant region, name these three parts in order.
Variable, diversity, joining.
52
How is one person is able to generate millions of different types of antibodies where each type of antibody can recognize/bind to a different epitope? What is this process called?
B cells have 65 different genes that it could code for the variable region, 27 different genes to code for the diversity region, and 6 genes to code for the joining region. These codes can be different on both the heavy and the light chains for the variable, diversity, and joining regions, and each B-cell can use a different combination.
Gene rearrangement.
53
Where in the body are stromal cells found?
bone marrow
54
Explain the role of stromal cells in eliminating potentially harmful immature B-cells.
They screen the immature b-cells before they leave the bone marrow by testing it to see if that b-cell can recognize a protein on its surface. If they do, the stromal cells perfom clonal deletion.
55
What is clonal deletion?
The process of stromal cells killing harmful immature b-cells that can recognize human proteins that are on the surface of stromal cells. The stromal cell releases molecules that cause the harmful immature b-cell to go through apoptosis.
56
True or False
Stromal cells play a role in clonal deletion of immature B-cells.
true
57
Which types of B-cells would be considered the “youngest” type?
Immature b-cells
58
Which of the following types of B-cells would be considered the “oldest” type?
Group of answer choices
Effector B-cell
59
An immature b-cell is the _____ b-cell. Once an immature b-cell leaves the bone marrow and is out patrolling, it is considered a _____ b-cell until it encounters an antigen.
youngest, naive
60
_____ b-cells have encountered antigens, whereas _____ b-cells have not. However, both b-cells are out of the bone marrow.
effector, naive
61
Another term for effector B-cell is ________.
plasma
62
When a B-cell is activated, the plasma cells it forms initially make a type of antibody called ________.
Immunoglobulin M; IgM
63
Why might it be useful for an IgM-to-IgA class switch to occur?
Different antibodies are better suited to fight off pathogens in certain situations or certain areas, and IgA is the most abundant antibody in mucosal surfaces. IgA also has a special structure that allows them to bind to pathogens in the stomach.
64
What structural feature(s) of IgA make it especially well-suited to bind to pathogens in the stomach?
the secretory component - it protects IgA against being cleaved by enzymes/acids found in mucousy secretions
65
Suppose that Plasma Cell #1 produces IgM. Plasma Cell #2 produces IgA. Both Plasma Cell #1 and #2 came from the cell activated B-cell. This means that the IgM produced by Plasma Cell #1 and the IgA produce by Plasma Cell #2 would bind to _____ epitope.
the same epitope
66
Naive b-cell encounters an epitope in the lymph node. This activates the b-cell so that it produces clones of itself. Some of these clones produce plasma cells. Some of the other activated clones travel to the germinal center within the lymph node.
Step one of affinity maturation
67
Why is affinity maturation useful? In other words, what does affinity maturation produce, and how does it help protect against disease-causing microbes?
It allows for the production, over time, of antibodies and memory b-cells that bind very well to an epitope (even better than the first b-cell that responded to an epitope).
68
Describe 2 reasons why memory B-cells are more effective than naïve B-cells at eliminating disease-causing microbes.
They have already undergone affinity maturation and they are now easier to activate.
69
What is Class switching?
Over time, plasma cells from the same activated B-cell start producing different types of antibodies.
70
What type of b-cell is still maturing in the bone marrow?
immature b-cell
71
Once in the germinal center, the activated clone undergoes hyper mutation, dividing to produce more clones with a very high chance of mutation. Some of these clones end up having b-cell receptors that bind tighter to the epitope than the original b-cell clone.
step two of affinity maturation
72
The b-cell clone that produces the best b-cell receptor is allowed to live, while the weaker b-cell clone dies off. This is determined when the follicular dendritic cell presents epitope to all the clones to see which one binds first and hangs on the best.
step three of affinity maturation
73
the "super" b-cell clone is activated to produce memory cells and plasma cells. These cells are then more effective than the ones originally produced.
step four of affinity maturation
74
Before patrolling the blood/lymph, T-cells must first develop in the ________.
thymus
75
Basically, developing T-cells undergo 2 different “tests” while they are developing in the thymus:
One: Immature T-cells that can recognize MHC molecules are ________.
Two: Immature T-cells that recognize (and bind to) molecules normally found in the body are ________.
Group of answer choices
allowed to live; killed off
76
True or false
Only B-cells can differentiate into memory cells. T-cells cannot differentiate into memory cells.
False - t-cells can too.
77
A denatured form of a toxin is called a _____.
Toxoid
78
Positive and negative selection is something that happens to _____.
Immature t-cells
79
What happens during positive selection? Why is positive selection important? !!!!!!! 5
immature t-cells that are developing in the thymus are tested to see if they can recognize MHC molecules. Those that can are allowed to live and those that cannot are killed off because they won't be able to recognize any foreign epitopes.
80
What happens during negative selection? Why is negative selection important? !!!!!!! 7
immature t-cells that are developing in the thymus are tested to see if they can recognize self antigens. Those that can are killed off because they could potentially cause harm to normal healthy cells
81
Vaccines typically contain:
- antibodies
- memory cells
- something that causes the production of memory cells.
Something that causes the production of memory cells
82
List 5 general types of vaccines:
Killed/ inactive pathogens, weakened (altenuate) pathogens, subunit vaccine, denatured toxin, and DNA vaccine.
83
What are the advantages and disadvantages of Killed/inactive pathogens?
Advantages: no chance of getting sick from it
Disadvantages: short lived protection, boosters required, and causes affinity maturated b-cells to become plasma cells
84
What are the advantages and disadvantages of Weakened (Altenuate) pathogens?
Advantages: They produce longer lasting protection
Disadvantages: They may revert to their pathogenic form
85
What are the advantages and disadvantages of Subunit vaccine (isolate specific antigen from pathogen)?
Advantages: No chance of developing disease
Disadvantages: produce relatively short lived protection because subunits aren't recognized by TLRs and boosters may be required
86
What are the advantages and disadvantages of a denatured toxin?
Advantages: No chance of developing disease
Disadvantages: produce relatively short lived protection because subunits aren't recognized by TLRs and boosters may be required
87
What are the advantages and disadvantages of a DNA vaccine (against viruses)?
Advantages: cheaper to mass produce and it exposes us to antigen in natural confirmation
Disadvantages: none currently approved for use
88
Another term for a white blood cell is a _____.
leukocyte
89
What makes adaptive immune cells different from innate immune cells?
adaptive immune cells can change or modify after coming in contact with a pathogen to become better equipped to fight off that pathogen.
90
Innate immune cells are _____ and _____, while adaptive immune cells are _____ and _____. Choose from the options below:
b-lymphocytes
t-lymphocytes
Macrophages
Neutrophils
macrophages and neutrophils, b/t-cells
91
ALL blood cells are derived from _______ cells.
hematopoietic stem cells
92
Where are hematopoietic stem cells found?
in the bone marrow
93
white blood cells can travel directly from the bone marrow to the _____.
circulatory system
94
white blood cells can travel directly from the circulatory system to the ______.
lymphatic system and tissues
95
white blood cells can travel directly from the tissues to the _____.
lymphatic system
96
white blood cells can travel directly from the lymphatic system to the _____.
circulatory system and tissues
97
what is the general function of the lymphatic system?
to bring leukocytes together with pathogens
98
What is the difference between primary lymphoid organs and secondary lymphoid organs?
primary lymphoid organs are where white blood cells are produced. secondary lymphoid organs are where mature white blood cells come into contact with invading microbes.
99
give two examples of primary lymphoid organs:
bone marrow and thymus
100
the thymus is were __-cells mature.
t-cells
101
list four areas of the body where secondary lymphoid organs are found:
breast, respiratory tract, GI tract, and genitourinary tract.
102
The fluid that eventually becomes lymph comes from _____.
the capillaries
103
True or false: white blood cells can exit the circulatory system and enter the lymphatic system.
True
104
True or false: The lymph found in the lymphatic system is returned back to the circulatory system as blood plasma.
True
105
B-cells and T-cells are both considered to be what type of immune cell?
adaptive immune cell
106
in general, T-cells have which of the following molecules on their surface?
- CD4
- b-cell receptor
- CD8
- t-cell receptor
- CD40
- cytokine receptor
- MHC I
- CD4
- CD8
- t-cell receptor
- cytokine receptor
- MHC I
107
In general, B-cells have which of the following molecules on their surface?
- CD4
- b-cell receptor
- CD8
- t-cell receptor
- CD40
- cytokine receptor
- MHC I
- b-cell receptor
- CD40
- cytokine receptor
- MHC I
108
True or false: All white blood cells have cytokine receptors.
True
109
CD4 are specifically found on_____ t-cells, while CD8 are specifically found on _____ t-cells.
helper t-cells, cytotoxic t-cells
110
What is the function of a CD4 and a CD8 molecule?
To strengthen the connection between the t-cell receptor and the foreign molecule
111
CD40 helps to activate _____.
B-cells
112
Which takes longer to activate, innate immune cells or adaptive immune cells?
adaptive
113
Which cells can give rise to memory cells?
B-cells and T-cells
114
What is an epitope?
A specific small part of an antigen that is recognized by b/t-cell receptors
115
True or false: Toll-like receptors tend to recognize specific epitopes.
False; they recognize antigens as a whole
116
True or false: B-cell receptors and T-cell receptors tend to recognize specific epitopes.
True
117
True or false: B-cell receptors made by the same person are all identical to one another, and they vary between person to person.
False; One person makes millions of different b-cells to help protect against many different pathogens
118
___-cells bind to free floating antigen.
B-cells
119
___-cells can only bind to antigen if that antigen is being presented by another cell.
T-cells
120
Staphylococcus is considered normal flora in which parts of the body?
Nose and skin
121
Corynebacterium is considered normal flora in which parts of the body?
Nose and throat
122
Streptococcus is considered normal flora in which part(s) of the body?
throat
123
Haemophilus is considered normal flora in which part(s) of the body?
throat
124
Bacteroides is considered normal flora in which part(s) of the body?
large intestine and urethra
125
Escherichia is considered normal flora in which part(s) of the body?
large intestine and urethra
126
Klebsiella is considered normal flora in which part(s) of the body?
large intestine
127
Lactobacillus is considered normal flora in which part(s) of the body?
large intestine and vagina
128
Actinomyces is considered normal flora in which part(s) of the body?
mouth
129
Propionibacterium is considered normal flora in which part(s) of the body?
skin
130
List and describe two types of relationships that normal flora can have with their human host.
Mutualism : The microbe and host both benefit
Commensalism: The microbe benefits but the host is unaffected
131
List and describe the type of relationship that pathogens can have with their human host.
Parasitism: The microbe benefits and the host is harmed
132
Briefly describe two things that prevents our cells from attacking the normal flora in our body.
Intestinal cells can differentiate between normal flora and pathogens.
Tregs suppress parts of the immune system so that normal flora do not become attacked.
133
why are intestinal cells are more likely to attack pathogens and not normal flora?
Pathogens invade our cells and trigger the TLRs in the cytoplasm. Normal flora do not invade our cells and therefore do not come into contact with TLRs.
134
List three functions of regulatory T-cells (Tregs).
It cuts down the amount of damage to our own cells during normal immune response.
Helps prevent allergic reactions.
Helps prevent our immune system from killing normal flora.
135
Describe how normal flora may indirectly activate regulatory T-cells. What other cells are involved in this process?
Normal flora can activate macrophages --> helper t-cells --> regulatory t-cells
136
Describe how normal flora may directly activate regulatory T-cells. What role do toll-like receptors play in this process?
A continuous presence of microbe is required to activate regulatory t-cells, and since normal flora is always in the body their presence is continuous. Short term binding, like with pathogens, cannot activate the Treg cells.
137
Describe two ways that regulatory T-cells suppress the immune response.
They prevent APCs from activating helper t-cells and they, and they soak up the signals (cytokines) that activate NK cells and helper t-cells
138
What’s the difference between a sign of disease and a symptom of disease?
Sign of disease are things that can be detected/ measured by people other than the person with the disease.
Symptoms are something that only the person with the disease can detect (anxiety, fatigue, etc.)
139
What is an opportunistic pathogen (general definition)?
Pathogens that can only make someone sick after the hosts immune system has been weakened by another infection
140
What does “virulence” mean?
It's a measure of how likely a microbe is to cause a disease
141
What is a virulence factor?
a trait or characteristic that allows a microbe to cause a disease
142
What is ID50?
infectious dose 50 - dosage of a pathogen required to make 50% of a population sick. The smaller the ID50 number, the more virulent a pathogen is
143
What are the stages of infectious disease?
Invasion by pathogen --> incubation period --> prodromal period (early signs and symptoms) --> illness period --> convalescent period (recovery)
144
Describe two general types of illness periods that a pathogen may produce.
acute and chronic
145
What is the difference between bacteremia, toxemia, and viremia?
bacteremia is when bacteria are in blood, toxemia is toxins in blood, and viremia is viruses in blood
146
What is a mechanism of pathogenicity?
any activity of a microbe that results in disease of the host
147
List four general mechanisms of pathogenicity.
- adhere, colonize, and invade host tissue
- evade innate defenses
- evade adaptive defenses
- damaging the host (ex. producing toxins)
148
What are adhesins and where are they found?
They are a molecule found on a bacterial structure (ex. pilus or capsule). They bind to a specific molecule on host cell.
149
What are siderophores? How do they help pathogens grow?
They are molecules released by some pathogens. They steal iron from it's host and deliver to the inside of the pathogen, as Iron is needed to make the complexes in the ETC.
150
Describe two ways that pathogens like SalmonellaIa can invade the cells that line the intestinal tract.
Salmonella can inject proteins into a host cell that alter the host cell's cytoskeleton. This causes the host cell to engulf the bacterium.
Salmonella allows M cells to deliver them across the intestinal membrane where they can then invade the immune cells and replicate, or even spread to other cells in the body.
151
Some pathogens (e.g. Mycobacterium tuberculosis) can evade the innate defenses by preventing macrophages from killing them. How do they do this?
They prevent fusion of lysosome with phagosome
152
Describe one way that Neisseria gonorrhea can evade the innate defenses.
They can produce sialic acid on their cell surface that can bind to a protein called factor H. When factor H binds to the surface of N. gonorrhea it prevents C3 from being cleaved and prevents the activation of other compliment proteins.
153
What’s the role of IgA protease in helping pathogens evade the adaptive defenses?
They can destroy (cleave) antibodies found on mucosal surfaces
154
What’s the role of Fc receptors in helping pathogens evade the adaptive defenses?
The Fc receptors on some pathogens cause antibodiesto bind to them so that the variable region is sticking out. This prevents activation of compliment proteins and NK cells.
155
What’s the role of syncytium formation (fusing together of host cells) in helping pathogens evade the adaptive defenses?
When the host cell fuses with neighboring cells, the virus can evade antibodies because the antibodies can only detect single, free floating pathogens.
156
What type of bacteria produce exotoxins? What type of bacteria produce endotoxins?
gram positive bacteria produce exotoxins, and gram negative bacteria produces exotoxins and endotoxins.
157
What type of molecule is an exotoxin? What type of molecule is an endotoxin?
exotoxin - protein
endotoxin - lipid (lipid A portion of LPS)
158
Can exotoxins be deactivated by heat? Can endotoxins be deactivated by heat?
yes, exotoxins can
no, endotoxins cannot
159
Are exotoxins secreted by bacteria? Are endotoxins actively secreted by bacteria?
exotoxins may or may not be secreted by bacteria
endotoxins are only release from bacteria if the bacterium dies
160
Name and briefly describe three general categories of exotoxin:
neurotoxins: interfere with nerve cell transmission
enterotoxins: interfere with function of intestinal cells (cause diarrhea)
cytotoxins: cause damage to a variety of cells
161
Name the three general categories of exotoxin:
A-B toxins, superantigens, and membrane damaging toxins.
162
What occurs if there is widespread endotoxin in the blood?
the blood vessels become leaky, leading to a sudden drop in blood pressure (septic shock).
163
Name three enzymes that may be released by pathogens, and cause damage to the host (by destroying connective tissue).
proteases, lipases, collagenases
164
Describe one example of how a pathogen can cause unintentional damage to its host, as a result of the host’s own immune response.
When our immune system responds to gonorrhea it can cause a lot of inflammation in the genitourinary tract which may cause scarring. That scarring can lead to infertility or ectopic pregnancy.
165
Describe an A-B toxin:
It has an A and a B subunit. The B subunit binds to a molecule on surface of human cell. The A subunit is what causes damage once inside the cell.
166
Describe superantigens:
They bridge the MHC II receptor with the t-cell receptor on the helper t-cells.. better than regular antigens do. This causes t-cells to become activated and release cytokines that may lead to shock, fever, and vomiting.
167
Describe membrane damaging toxins:
They form pores on the surface of our cell membranes and trigger inflammation. This happens because they are recognized by the TLRs of macrophages and it leads to pro-inflammatory cytokines being released.
168
Describe two antimicrobial activities of intestinal cells:
Intestinal cells can deliver pathogens from one side of the intestinal tract to the other. This allows dendritic cells and macrophages to take in the pathogen
intestinal cells release antimicrobial substances that can directly kill some pathogens.
169
What is “balanced pathogenicity”? Why would it be useful for both pathogen and host?
if a pathogen is too pathogenic it will kill the host before it has the chance to spread. Balanced pathogenicity allows the host to survive and the pathogen to transmit at an optimal level.
170
What is epidemiology?
study of disease patterns (how disease is spread) in a population
171
Explain the difference between these terms: Incidence vs. Prevalence
Incidence is the number of new cases of disease in a population over a defined time, and prevalence is a number of total cases of disease in a population over time
172
Explain the difference between these terms: Morbidity vs. Mortality
Morbidity is the number of new cases within a population, and mortality is the number of people who die from a disease within a population.
173
Explain the difference between these terms: Endemic vs. Epidemic vs. Pandemic
endemic is a disease that is always present (in low levels) within a population. Epidemic is the occurrence of an unusually high number of disease cases. Pandemic is an epidemic that spread around the world.
174
What are Koch’s Postulates used for?
it provides a way of identifying the cause of a new disease
175
List/describe Koch’s Postulates in order.
1. microorganisms are isolated from a dead animal
2. microorganisms are grown in pure culture and identified
3. microorganisms are injected into a healthy animal
4. the disease is produced in the second animal and then the microorganisms are isolated from the animal
5. pathogenic organisms are grown in pure culture and identical microorganisms are identified
176
What are Molecular Koch’s Postulates used for?
determination of a molecule as a virulence factor
177
List/describe Molecular Koch’s Postulates in order.
1. molecule must be present in all strains that cause disease
2. mutating the gene for the molecule must decrease the virulence of the microbe
3. restoring the gene must restore the microbes virulence
178
What’s the definition of a disease reservoir?
it's the natural habitat of a pathogen and the continuous source of disease in a potential outbreak.
179
List 3 general types of disease reservoirs.
humans, non-human animals, and the environment (soil or water)
180
describe what a zoonose is:
it is a disease mostly found in animals but has the potential to spread to humans.
181
Describe the difference between vertical and horizontal transmission:
vertical transmission - from mother to child in utero, during child birth, or while breast feeding
horizontal transmittion - every other disease transmission that is not vertical
182
Name 6 ways that diseases may be transmitted horizontally.
direct contact, indirect contact (touching something that was exposed to someone with the disease), droplet transmission (occurs btwn ppl no more than one meter apart), airborne transmission, food and water, vector transmission (transmission via insect).
183
describe what a fomite is. What type of disease transmission are fomites related to?
it is an inanimate object that can transfer disease - horizontal (indirect contact)
184
List 6 common portals of entry for pathogens
eyes, ears, respiratory tract, genitoururinary tract, digestive tract, and broken skin.
185
List 4 common risk factors that might make someone more prone to getting a disease.
percentage of population that's currently immune to disease, general health and living condition, age, and genetic background.
186
describe what “herd immunity” is.
when enough people within a population are immune so that infection of one person does not cause epidemic
187
Describe two types of studies that may be conducted to determine the risk factors of a disease.
a retrospective study (looking back in time), and a prospective study (looking forward in time).
