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Biology 109 Test #3 > The Immune System > Flashcards

The Immune System Flashcards

1
Q

What is a pathogen?

A

Bacteria, fungi, virus, etc…

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2
Q

How does innate immunity work? Is it fast or slow?

A

Recognizes traits that are shared by a broad range of pathogens using a small set of receptors.

Rapid response

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3
Q

Do all animals have innate immunity?

A

YES

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4
Q

What are the two types of defenses that the innate immunity provides humans with? What do these defenses consist of?

A

Barrier defenses - skin, mucus membranes, secretions

Internal defenses - Phagocytic cells, NK cells, antimicrobial proteins, inflammatory response

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5
Q

How does adaptive immunity work? Is it fast or slow?

A

The recognition of traits specific to particular pathogens using a vast array of many receptors.

Slower response

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6
Q

Do all animals have adaptive immunity?

A

NO, just vertebrates.

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7
Q

What are the two responses of the adaptive immunity and what do they consist of?

A

Humoral response - antibodies defend against infection IN BODY FLUIDS

Cell-mediated response - cytotoxic cells defend against infection IN BODY CELLS

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8
Q

Describe the innate immunity of invertebrates, for example an insect, separate into barrier and internal defenses.

A

Barrier - exoskeleton, digestive system has low pH and lysozyme (break down cells walls of bacteria)

Internal - Hemocytes in hemolymph carry out phagocytosis and secrete AMP (antimicrobial peptides), bacteria and fungi are recognized due to their unique molecules on cell walls and the immune response varies based on the class of pathogen encountered.

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9
Q

Understand this picture that covers phagocytosis

A

DO IT

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10
Q

Look at this graph of fruit fly infection and understand how different AMPs help to defend against DIFFERENT pathogens in the innate immunity.

A

Mutants produce no AMPs.

Drosomycin and defensin are AMPs

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11
Q

Have a basic understanding of antiviral defense in insects based on this picture. The steps are listed in the book.

A

:)

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12
Q

For vertebrates, describe the different barrier defenses that are present in the innate immunity. What is the purpose of mucus?

A

Barrier defenses:

Skin

Mucus membranes of digestive, respiratory, urinary, and reproductive tracts. Mucus traps microbes and other particles

Saliva, mucus, and tears contain lysozyme that destroy susceptible bacteria

Low pH of skin and digestive system prevents microbe growth

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13
Q

Describe TLRS of the internal defense of innate immunity that are present in phagocytic cells, what are the 4 types of phagocytes found in mammals?

A

Phagocytes:

Phagocytes have TLRs - toll-like receptors, bind to lipopolysaccharide (endotoxin), flagellin, and other pathogenic proteins.

Mammalian Phagocytes:

Neutrophils - most abundant

Macrophages - Large, found throughout the body and are part of lymphatic system

Eosinophils - release destructive enzymes to combat MULTICELLULAR INVADERS (like worms)

Dendritic cells - stimulate development of adaptive immunity

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14
Q

What do dendritic cells have that distinguish them?

A

Tree-like branches

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15
Q

What is the difference between a monocyte and a macrophage?

A

Monocytes reside in the blood stream, but when they migrate to tissues they become macrophages OR dendritic cells.

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16
Q

What is the other cell type that are a part of the internal defense of the innate immunity? What is their function?

A

NK cells - help recognize and eliminate certain diseased cells,.

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17
Q

What is an example of a diseased cell that NK cells might eliminate?

A

Cancerous or infected cells.

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18
Q

How does an NK cell know when a cell is cancerous or diseased?

A

Normally all nucleated cells in the body have MHC (major histocompatibility complex) class I proteins on their surface.

Cancerous of infected cells no longer express this protein, so NK cells know they need to be eliminated.

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19
Q

What is an example of a cell that doesn’t have a nuclei, and, therefore doesn’t express MHC class I?

A

RBCs.

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20
Q

Where is the lymphatic system do both macrophages and lymphocytes reside to engulf pathogens?

A

The spleen and lymph nodes

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21
Q

Describe the antimicrobial peptides and proteins portion of the internal defenses of the innate immunity in vertebrates. What are interferons and the complements system?

A

Pathogens that are recognized in mammals stimulate the release of peptides that attack microbes. Some of these are similar to the AMPs that are released in insects.

Interferons - proteins that provide innate defense against viruses and help to activate macrophages. These are released from the infected host cells to neighboring cells to tell them to INTERFERE.

Complement system - made up of about 30 proteins, causes lysis of invading cells and to help trigger inflammation. Produced by liver and circulate in an inactive state.

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22
Q

Where are NK cells derived from?

A

LYMPHOID STEM CELLS

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23
Q

What are the four cardinal signs of the inflammatory response that is part of the internal defense of innate immunity?

A

Redness (rubor, erythema) - increased blood flow

Heat (calor) - increased blood flow

Swelling (tumor, edema) - leaky blood vessels

Pain (dolor)

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24
Q

What is the function of MAST cells in the inflammatory response? What is the function of histamines?

A

Release histamines at sites of tissue damage

Histamines - cause blood vessels to dilate and become more permeable.

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25
What role do neutrophils and macrophages play in the inflammatory response?
Release cytokines that increase blood flow to the site of infection or injury,
26
What is pus that accumulates at sites of inflammation?
Fluid that is rich in WBCs and debris from damaged tissue.
27
What is the purpose of dilating blood vessels and increasing permeability in the inflammatory process?
To increase local blood supply and allow more phagocytes and AMPs to enter tissues.
28
MAST cells and basohils are similar cells, but what makes them differ?
Basophils reside in blood while MAST cells reside in tissues.
29
Do invertebrates have an inflammatory response?
NO
30
Be able to describe the major events of the inflammatory response described in this picture.
DO IT. 1. MAST cells release histamines to dilate capillaries and permeate them, macrophages release cytokines to attract neutrophils 2. Capillaries widen and become permeable, neutrophils and fluid containing antimicropbial peptides enter the tissue 3. Neutrophils digest pathogens and cell debris at site of injury, tissues eventually heals.
31
What is happening in step 2 of this picture?
1. Margination - blood cells slow down and attach to endothelial cells. 2. Diapedesis - or extravasation, is the passage of blood cells through intact capillaries, usually during inflammation.
32
Can the inflammatory response be either local or systemic?
YES
33
What is a specific systemic inflammatory reponse? What causes this?
Fever Caused by pyrogens released by macrophages
34
Can a fever be a good thing?
YES Fever – believed to not only further stimulate immune system, but help to denature bacterial proteins to decrease bacterial proliferation.
35
What is sepsis? What is thought to be the phenomenon that cuases this?
A life-threatening condition caused by an overwheling inflammatory response due to an infectious process. A cytokine storm usually causes this overwhelming inflammatory response
36
Can inflammation be acute or chronic?
YES
37
Have a basic understanding of the sepsis continuum.
...
38
What are the three lymphocytes and what immune response do they tend to? Where do they come from?
They all come from lymphoid stem cells: T and B cells - adaptive immunity NK cells - innate immunity
39
Where do B cells mature? Where do T cells mature?
B cells - mature in the bone marrow T cells - mature in the thymus
40
Where are the stem cells that make blood cells located?
Bone marrow
41
What is immunological memory? What cells contribute to this?
This is an enhanced immune response to a foreign molecule that was encountered previously T and B cells contribute to this
42
What is the function of cytokines which are released by macrophages and dendritic cells in the adaptive immune response? What does this show?
Cytokines recruit and activate lymphocytes This shows that there is an overlap between the innate and adaptive immunity
43
What is an antigen?
Any foreign molecule to which a lymphocyte responds
44
How many IDENTICAL antigen receptors does a single T or B cell have on its surface?
about 100,000
45
What is meant by specificity of lymphocytes?
All of the antigen receptors on a single lymphocyte recognize the same epitope on an antigen.
46
What is an epitope?
This is the accessible portion of an antigen that binds to an antigen receptor This is the antigenic determinant
47
What do B-cell antigen receptors look like?
Shaped like a Y
48
The Y shaped B cell antigen receptor has 4 total chains, but how are they paired?
2 identical heavy chains and 2 identical light chains.
49
What anchors the B cell antigen receptors to the B cell?
The transmembrane region of the heavy chains.
50
What two regions do all chains of the B cell antigen receptor have?
They all have a constant region and a variable region
51
What is the significance of the variable regions of the light and heavy chains of the B cell antigen receptors?
These have varying amino acid sequences from one B cell to another that make up the antigen binding site.
52
What do the antigen receptors of B cells bind to?
specific INTACT antigens
53
How many antigens can one B cell antigen receptor bind to? (think of the Y shape)
2
54
What happens after a B cell antigen receptor binds to an antigen?
The B cell is activated and will proliferate and then differentiate into memory cells and effector (plasma) cells.
55
What happens when a B cell antigen receptor binds to an antigen and gives rise to plasma (effector) cells?
These plasma cells secrete antibodies (immunoglobulin), which are soluble forms of the B cell antigen receptor.
56
What do antibodies lack that B cell antigen receptors have?
A transmembrane region.
57
What are the two things that happen when a B cell is activated?
1. clonal expansion: proliferation of the B cell 2. Differentiation: Cells specialize and become either a plasma (effector) cell or become a long-lasting memory cell.
58
What are the antigen receptors specifically binding to on antigens?
The epitopes.
59
How des a T cell antigen receptor differ from a B cell antigen receptor? How are they the same?
T cell antigen receptor: - binds to fragments of antigens presented by host cells - have 2 chains: 1 alpha and 1 beta chain, not Y shaped - not secreted, always bound to plasma membrane B cell antigen receptor: - Bind to intact antigen with no need for host cell - have 4 chains: 2 heavy and 2 light, Y shaped - can be secreted as antibody Both: - have a variable region and a constant region - have a transmembrane region
60
What are some examples of antigen presenting cells?
-Antigen presenting cells (APCs): Macrophages. Dendritic cells, and B cells
61
What is MHC II and what is its role in antigen presentation?
Major histocompatibility complex II This is used in our antigen presenting cells as well as infected cells to transport antigen fragments from the inside of the APC to the cells surface (antigen presentation). MHC II is the molecule that presents the antigen fragment on the surface of APCs.
62
After an APC presents an antigen what happens?
A T cell detects the antigen fragment and binds to it as well as the MHC II. This activates the adaptive immune response.
63
What two things happen when a T cell is activated by an antigen presenting cell?
1: proliferation - the T cell divides rapidly 2: differentiation - specialize into memory T cells or effector T cells (T helper or cytotoxic T cells)
64
What are the four important properties of adaptive immunity?
1. B and T cell receptor diversity 2. Self-tolerance (preventing autoimmunity) 3. Proliferation of B and T cells 4. Immunological memory
65
Describe the 1st property of the adaptive immune response, the B and T cell diversity. What accounts for the diversity?
The variable region
66
Describe the 1st property of the adaptive immune response, the B and T cell diversity. How is it that a B and T cell can produce so many different receptor sites? Elaborate?
Through DNA rearrangement or DNA shuffling Random sites of the gene are chosen to be used vs. being deleted in regards to expression of the receptor as the cell differentiates. This process allows for the many different types of receptors.
67
How many million different T and B cell antigen receptors can be made?
B - 1 million T - 10 million
68
Describe the second important property of the adaptive immune response: self-tolerance. How is this ensured?
Lymphocytes are tested for self-reactivity as they mature in the bone marrow or the thymus. If lymphocytes are found to be self-reactive, or they have receptors specific for the bodies own molecules then they are either rendered nonfunctional or are destroyed via apoptosis.
69
Describe the third important important property of the adaptive immune respone: proliferation of B cells and T cells.
Binding of an antigen activates mature lymphocyte to divide rapidly. This rapid division is known as proliferation, or clonal selection.
70
What happens to the cells that are produced by clonal selection?
The proliferated cells of both either turn into: short-lived effector cell long-lived memory cell
71
What are the effector cells of B cells vs. T cells?
Effector cells: B - plasma cells (secrete antibodies) T - either T helper or cytotoxic T cells
72
Describe the fourth important aspect of the adaptive immune response: immunological memory. What differs between the primary response and the secondary response.
Primary - The first exposure - plasma cells produced, response peaks 10-17 days after exposure. low and slow. Secondary - second exposure to same antigen - response is of greater magnitude and response can be prolonged due to reservoir of memory cells and rapid response of plasma cells. peaks 2-7 days after exposure.
73
The adaptive immunity is divided into 2 divisions, what are they? What is a basic description of them?
Humoral response - activation and clonal selection of B cells resulting in production of antibodies Cell-mediated response - activation and clonal selection of cytotoxic T cells.
74
Which cell aids in both responses of adaptive immunity?
Helper T cells
75
Describe the differences between MHC I and MHC II. Where are they found? What do they present? What do they activate?
MHC I: - found on every NUCLEATED cell in the body - present endogenous antigens like viral fragments or tumor proteins - antigens presented to cytotoxic T cells MHC II: - found on B-cells, macrophages, and other APCs - Present exogenous antigens such as digested fragments of foreign cells - present antigen to helper T cells
76
Do helper T cells respond to nearly every antigen?
YES
77
Describe T helper cell activation.
Accessory protein on helper T cell binds to MHC class II on the APC. Remains bound while activation occurs. Activated cell secretes cytokines that stimulate other lymphocytes.
78
Look at this picture and understand helper T cells role in both cell-mediated and humoral immune response.
1. APC engulfs pathogen, degrades it, and presents fragment on MHCII molecule. specific helper T cell binds to it. 2. After binding, the APC AND the helper T cell secrete cytokines to activate the helper T cell to prloferate. 3. The clonal selection produces more t helper cells that have same receptor for antigen. more cytokines are released by these cells that activate B cells and cytotoxic T cells.
79
What adaptive immune response are cytotoxic T cells are part of?
These are EFFECTOR cells that are a part of the cell-mediated adaptive immune response.
80
What cells fo cytotoxic T cells respond to specifically?
Infected cells that display antigen via their MHC class I molecules on their surface.
81
What happens when a cytotoxic T cell responds to signals from T helper cells and binds to a MHC I complex of an infected cell?
It becomes an active killer that secretes proteins (granzymes that break down proteins, or perforins that make pores on surface of cell causing it to lyse) to destroy the infected cell.
82
What aids in the activation of B cells for the humoral response to occur?
cytokines antigen binding to helper T cells
83
What are the 3 ways that antibodies function to dispose of pathogen?
1. neutralization - antibodies bind to antigens on surface of pathogen (virus or toxin, something smaller than bacteria) blocking its ability to bind to a host cell. 2. Opsonization - binding of antibodies to antigens on surface of bacteria promotes phagocytosis. 3. Activation of complement system - antibodies bind to surface antigen of pathogen, complement system is activated, membrane attack complex is created and forms pores in cells membrane which lyses the cell.
84
Look at this overview diagram of the humoral and cell-mediated adaptive immune responses and understand it.
DO IT. P. 965.
85
What is the difference between active and passive immunity?
Active: - own immune response develops immunity - slower longer lasting Passive : - Immunity was developed elsewhere and passed on to individual - immediate - short-term
86
Give both natural and artificial examples of active and passive immunity.
Artificial: Active - immunizaion that requires body to mount immune response to injected inactive pathogen or particle of pathogen Passive - antibodies being injected into non-immune person, tetanus booster, antivenom Natural: Active - Response to an infection Passive - IgG that crosses placenta to fetus, IgA that is passed to fetus from mothers breast milk
87
What is the definition of immunization?
Process in which a nonpathogenic form of microbe, or part of a microbe, elicits a immune response and forms immunological memory.
88
What is the difference between polyclonal and monoclonal antibodies?
Polyclonal - products of many different B cell clones following exposure to antigen. These recognize DIFFERENT epitopes on the same antigen. Monoclonal - products of a single clone of B cells usually grown in culture, these recognize a SINGLE epitope on the same antigen
89
Do we use ntibodies for a variety of things?
YES research, home pregnancy tests, treatments for various diseases (cancer, etc...)
90
What is immune rejection? What is this caused by?
This is when cells transferred from one person to another are attacked by immune defenses. MHC molecules differ between non-genetically identical individuals.
91
What does immune rejection cause an issue for? What are some important factors to consider for these?
Organ transplantation and blood transfusions Increased chance of successful transplantation if donor MHC molecules closely match those of the recipient. Immunosuppressive drugs are also given to facilitate the success of transplant.
92
What are allergies?
Hypersensitive responses to antigens.
93
What is another name for an antigen that cuases an allergic response?
allergen
94
How do allergies develop?
After the first exposure to the allergen, igE that has been produced attached to MAST cells. The next exposure to allergen facilitates binding of allergen to MAST cell associated IgE molecules. This causes the release of histamine which causes symptoms of hay fever.
95
What is anaphylactic shock?
An acute allergic response that can occur within seconds of exposure and is life-threatening.
96
What is an autoimmune disease? What are some examples?
The immune system loses tolerance for self and attacks certain molecules of the body. SLE, MS, DM I, RA
97
What is the difference between inborn immunodeficiency and acquired immunodeficiency?
Inborn - resulting from hereditary or developmental defects that affect an aspect of the immune system (sever combined immunodeficiency - lack functional lymphocytes). Acquired - results from chemical exposure or exposure to biological agent (HIV)
98
What is meant when it is said that a pathogen has antigen variation? Examples?
Pathogens can change the epitopes that they express to prevent recognition and evade attack. Inlfuenza mutates rapidly, new vaccine needed every year. Human viruses have exchanged genes with animal viruses which changes antigenic expression. Swine flu (H1N1) is an example of this.
99
What does it mean when a virus can undergo latency? What are some examples of this?
This is when a virus can enter into an inactive state and not cause any symptoms. Herpes simplex virus can be latent and when stressful stimulus occurs: - Type I - leads to cold sores around mouth Type II - causes genital sores Type III or VZV - Chickenpox when younger then can remain dormant and become activated again with stress or other stimulus and cause shingles.
100
What cells does HIV infect? What does this cause? antigenic variation? Latency?
CD4+ cells (T helper cells) - CD4+ cells lose function - Shows latency and antigenic variation - Makes people susceptible to oppotunistic infections and cancers that take advantage of immunodeficiency.
101
Have a basic understanding of this graph that shows the progress of untreated HIV infection.
- Blue line - Concentration rapidly increases for first 6 months, drops after most of HIV DNA is integrated into helper T cells and is replicationg. - Red line - antibodies are being performed but aren't enough to fend off infection due to antigenic variation and latency. - Black line - T cells are dying off as virus infections and kills them
102
Can immunodeficiency increase the risk for certain cancers? Example?
YES Kaposis sarcoma risk is 20,000 times greater in untreated AIDS patients - Viruses are involved in 15-20% of all human cancers, immune system can't protect against these viruses. HPV is an example that causes cervical cancer, vaccination against HPV exists to prevent cervical cancer.
103

Biology 109 Test #3 (5 decks)

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