Immunology Flashcards
(108 cards)
1
Q
What is the role of the immune system?
A
To resist or eliminate pathogens from the body
2
Q
What are pathogens?
A
Harmful foreign materials
3
Q
What are the two sections of the immune system?
A
Innate (non-specific)
Adaptive (specific)
4
Q
What section of the immune system is activated first?
A
If a pathogen invades the physical barriers, the first thing it encounters is the innate immune system
5
Q
What are the features of the innate immune system?
A
It is existent from birth
Produces the same response to every pathogen
No immunological memory
6
Q
When is the adaptive immune response activated?
A
When the attack is severe or prolonged and the innate immune system is unable to attack the invading pathogen
7
Q
What are the features of the adaptive immune system?
A
Exhibits immunological memory
Highly specific, creating a different response depending on the type of pathogen
8
Q
What are the two divisions of the adaptive immune system?
A
Humoral
Cellular
9
Q
What does the humoral adaptive immune response involve?
A
It involves B-lymphocytes
Secretes antibodies to fight against antigens
10
Q
What does the cellular adaptive immune response involve?
A
It involves T-lymphocytes
Secretes cytokines
11
Q
What is the humoral response effective at getting rid of?
A
Free-floating pathogens
12
Q
What is the cellular response effective at getting rid of?
A
Cells that have been infected by pathogens
13
Q
Is the humoral response rapid or delayed?
A
Rapid
14
Q
Is the cellular response rapid or delayed?
A
Delayed, though the action is permanent
15
Q
Do the innate and adaptive response interact with one another?
A
Yes
16
Q
What is the first line of defence?
A
Physical and chemical external barriers
17
Q
What are physical barrier examples?
A
Epithelial layer
Mucous - able to coat the cell surfaces in mucous, which traps pathogens and prevents viral entry to the body
Cillia - hair-like structure which is found in epithelial cells, sweep the trapped pathogens in mucous away from the lungs
18
Q
What are chemical barrier examples?
A
Sweat - ensure a low pH on the skins surface to prevent bacterial growth as bacteria are unable to grown in areas of low pH
Acid - destroy harmful microorganisms that are swallowed, as creates a low ph which bacteria are unable to grow in
Tears - contain lysozyme enzymes which are involved in digesting the bacterial walls of microbes
19
Q
What is the second line of defence?
A
The innate immunity
20
Q
When is the second line defence activated?
A
If the physical and chemical barriers fail to destroy the pathogen
21
Q
What cells are involved in the innate immune response?
A
WBCs - monocytes, eosinophils, lymphocytes, neutrophils and basophils
NK cells
Complement proteins
22
Q
What process produces WBCs? Where does this process occur?
A
Haematopoiesis
Bone marrow
23
Q
What does haematopoiesis involve?
A
Coverts hematopoietic stem cells into specialised white blood cells
24
Q
What are neutrophils?
A
Granulocyte white blood cells, as they contain granules of enzymes in their cytoplasms
They act as phagocytes, which are cells that engulf pathogens in phagocytosis
25
What is the process of phagocytosis?
1. Movement of the phagocyte towards the pathogen
2. Specific attachment of the pathogen's antigens to the phagocyte surface receptors
3. Endocytosis of the pathogen
4. Formation of the phagosome, which is vacuole around the pathogen
5. Fusion of the phagosome with lysozyme enzymes
6. These lysozyme enzymes digest the pathogen cell wall and other microbial proteins, thus killing it
7. These fragments are then presented on the phagocyte as antigens. The phagocyte is converted into an antigen-presenting cell, which can then activate other cells and alert them to the fact that there is a foreign pathogen present in the body.
26
What are monocytes?
They are phagocytes, which means that they carry out phagocytosis
They are agranular, which means that they don't contain granules of enzymes in their cytoplasm
27
Where are monocytes found?
Monocytes travel in the blood for 72 hours, after which they migrate to connective tissue to convert into monocyte-macrophages.
28
What are the differences between neutrophils and monocytes?
**Neutrophils...**
Granular WBCs
Present only in blood
Rapid response
Short life span
**Monocytes..**.
Agranular WBCs
Blood borne but migrate to tissues
Slow response
Long life span
29
What are eosinophils?
Granular WBCs - due to the fact that they contain granules in their cytoplasm that contain enzymes.
They combat parasitic infections.
They are involved in allergic and asthma reactions
30
Where are eosinophils found?
Travel in blood for 12 hours after which they survive in tissue for 12 days in the absence of stimulation
31
What are mast cells?
Granular WBCs - due to the fact that they contain granules in their cytoplasm that contain enzymes. Common enzyme - histamine
Involved in fighting parasites.
They are also involved in an allergic reaction, which if severe enough can cause anaphylactic shock
32
Where are mast cells found?
Connective tissue
33
How do mast cells cause anaphylactic shock?
1st exposure to allergen individual makes IgE antibodies against it. These antibodies can bind to mast cells.
2nd exposure to allergen, the antibodies bound to the mast cells can also bind to the allergen. Signal sent to mast cell to release enzymes into tissue, such as histamine.
Histamine causes vasodilation of the blood vessels and increases permeability of surrounding capillaries. This allows more immune cells to leak into the tissues, which stimulate the movement of cells towards the trauma site.
This is usually a local effect but if the toxin spreads throughout your body it can trigger massive cell degranulation and have serious effects.
34
What are basophils?
They are granular WBCs - due to the fact that they contain granules in their cytoplasm that contain enzymes. Enzymes are inflammatory mediators. Common enzyme - histamine
Function not proven but found in parasitic infections
35
What are NK cells?
Granular WBCs - due to the fact that they contain granules in their cytoplasm that contain enzymes.
Involved in killing virus and baceria infected cells.
Cause apoptosis.
36
Describe the proccess of apoptosis
Once NK cells detect forieng anitgens, they release enzymes contained within their granules.
Enzymes result in target cell's nucelus producing a self-destructive enxyme that reuslts in DNA and vital protiens being broken down into useless fragments
Cell shrinks and dies.
Remains ingested by phagocytosis
37
What are complement protiens?
Group of 20 protiens found in blood plasma. We refer to them as C1, C2, etc.
Involbed in killing microbes
Involved in enchancing the immune response.
Involved in bridging the gap between the innate and adaptive immune response
38
How are complement protiens activated?
Three pathways...
* Classical Pathway - foreign antigen indentified by antibody
* Alternative Pathway - carbohydrate bidning to a microbe
* Lectin Pathway - lectin (sugar binding protiens) binding to microbial polysaccharides
When one protien is activated, it ineracts with another, to result in its actoavtion. They are therefore activated in a cascade effect.
39
What do the three pathways that activate complementary proteins result in?
Membrane attack complex (MAC) forming. Complex makes a whole in the pathogen, which results in lysis of the target cell.
Oposonisation of pathogens
Inflammation
40
What are memory cells?
Lymphocytes which are able to remember the pathogen that they fought
41
What is the most abundant complement protein?
C3, as it is a key protien in all three of the pathways
In the blood and tissues, it is being cleaved into smaller fragments known as C3a and C3b.
42
What are cytokines?
Proteins secreted by immune cells
Allow cell-cell communication and are therefore signalling molecuels
Involved in both innate and adaptive immune response
43
What is the inflammatory response's role?
To inactivate foreign pathogens and facilitate tissue response
44
What are the symtpoms of the inflammatory response?
Redness, fever, swelling and pain
45
What is the third line of defence?
Adaptive immune response
46
What occurs during the inflammatory response?
Chemical mediators are released from inflammatroy cells, such as histamine.
Results in vasodilation of blood vessels, increased permeability of local capillaries.
This results in immune cells gathering at the site of injury and the dead tissue being cleaned up
47
How are the cells involved in the adaptive immune response specific?
They have a receptor which is complementary to the shape of an antigen on a pathogen
48
What is the lymphatic system?
Network of vessels that carry lymph and lymphoid tissue/organs through which the lymph travels
Includes all the structures dedicated to the circulation and production of lymphocytes - spleen, thymus and bone marrow.
49
What are the two types of lymphatic organs?
Primary
Secondary
50
What are primary lymphoid organs?
Involved in the production and circulation of lymphocytes
51
What are secondary lymphoid organs?
Organs that lymph travels through
Where the lymphocytes can be activated by antigens
52
How is lymph moved through the vessels?
Contraction of skeletal mucsles
53
What are the three roles of the lymphatic system?
Draining fluids from tissue
Absorpting and transporting fatty acids and fats
Immunity
54
What are the two primary organs?
Bone marrow and the thymus
55
Where are B-lymphocytes developed and matured?
Bone marrow
56
Where are T-lymphocytes developed and matured?
Developed - bone marrow
Matured - thymus
57
What process develops lymphocytes? What does this involve?
Haematopoiesis.
Haematopoietic stem cells undergoing differentuation to form specialised WBCs.
58
What is the thymus?
A bi-lobed organ situated between the lungs.
Divided into an ourter cortex and an inner medulla.
The outercortex contains a collection of T-lymphocytes but the medulla contains T-cell precursors
59
What are mature naive lymphocytes?
Lymphocytes that have matures but haven't met their specific antigen yet, which means that they haven't been activated yet.
60
What are the two main secondary organs
Lymph nodes
Spleen
61
Where are lymph nodes found? What are their role?
Located at intervals along the route the lymph takes while being transported back to the blood.
Have access to antigens encountered in most tissues therefore are places where lymphocytes can bind to antigens
Lymph nodes have incoming lymphativs which bring lymph into the node and outgoing lymphatics which take the lymph out of the node
They also have incoming blood vessels
62
Where is the spleen found? Describe its structure. What is its two main roles?
Left upper quadrant of the abodemen.
It has a dense connective tissue capsule, that divideds the organ into two compartments; red and white pulp
Red pulp - blood filter, removing ageing and damaged blood cells.
White pulp - initiates the immune response to blood-borne antigens.
63
What are the two types of T-lymphocytes?
Helper T-lymphocytes (Th cells)
Cytotoxic T-lymphocytes (Tc cells)
64
What is the role of Th cells?
Activate other immune cells by releasing cytokines.
Dont destroy an infected cell, instead shout for help so that cells which can destroy the infected cell arrive
65
How are Th cells activated?
By their receptors binding to the antigens on the surface of the pathogen or antigen presenting cell.
Their receptors are specific and can distinguish between the body's self cells and foreign cells.
66
What are the two types of T-cell selection?
Positive and negative
67
What process occurs when T cells and B cells are activated? What does this involve?
Clonal selection.
Clone of activated T-cells/B-cells and memory T-cells/B-cells are formed
68
What receptors are found on Th cells? What are their role? When do they ONLY function?
CD4+ receptors (TCR receptor)
Allows Th cells to recognise antigens
When they are bound to MHC II
69
What is MHC II? What is its role? How many proteins is it formed from?
A molecule found on all antigen precenting cells.
Allows Th cells to recognise self cells and therefore prevent them from attacking the body's own cells and only attacking wehn a cells presents a foreign antigen.
Two
70
How are Tc cells activated?
Their receptor binding to a foreign antigen.
Their receptors are specific and allow them to distinguish between the body's own cells and foreign cells.
71
What is the role of Tc cells?
Release perforin from thier granules in thier cytoplasm. This protein forms pores in the target cell.
They also release granzyme B (protease) which enters the target cell through the pore
This induces apoptosis
72
What always happens after apoptosis?
Remains are engulfed by phagocytosis
73
What receptors are found on Tc cells? What are their role? When does the receptor fucntion?
CD8+ receptors (TCR receptors)
Allow Tc cells to recognise antigens
When bound to MHC I
74
What is MHC I? What is its role? How many proteins is it formed from?
A molecule found on all nucelated cells
Allows Tc cells to recoginsie self cells and therefore prevent them from attacking the body's own cells and only attacking when a cell presents a foreign antigen
One
75
What is T-cell selection?
A process that allows T-cells to develop without being self-reactive and causing immunity
76
What happens during positive T-cell selection?
1. T-cells not expressing CD4+ or CD8+ enter the thymus from bone marrow.
2. Migrate to the cortex of the thumus and proliferate
3. During this proliferation, they begin to express CD4+ and CD8+
4. Receptors then bind to MHC class molecules in order to function. T-cells which are incapable of binding to MHC class molecules undergo apoptosis. T-cells which successfully bind survive
77
What occurs during negative T-cells selection?
T-cells that have TCRs that bind too strongly to their MHC class molecule have a higher likliehood of being self-reactive and attacking our own cells. Negative-selection identifies these cells and causes them to undergo apoptosis
78
What receptor allows antigens to bind to the B-cell?
BCR
79
What is neutralisation (related to antibody function)?
Antibody neutralises any effect a foreign antigen or pathogen has biologically
Preventing intial infection and cell-cell spread
80
What is the role of B-lympocytes?
To release antibodies
81
How are B-cells activated?
Their receptor binds to an antigen on a pathogen, activated T-cell or antigen presenting cell
82
Describe the structure of antibodies.
Made up of a heavy and light chain.
* Light chain is made up of a smaller polypeptide chain and is the section that binds to the antigen to form the antibody-antigen complex.
* Heavy chain is made up of a larger polypeptide chain and is not involved in the binding of the antigen.
Two regions in antibodies; Fc region and antigen binding region.
* The antigen binding region is a variable region that differs between different B-cells allowing them to bind to different antigens.
* Fc region is a constant region which is the same for all Ig of the same class
83
What are the five classes of antibodies?
* IgM
* IgG
* IgA
* IgE
* IgD
84
What is the role of IgM antibodies?
Fixing complement
Oposinzation
85
What is the role of IgG antibodies?
Oposinzation
86
What is the role of IgA antibodies?
Protects mucosal surfaces and is resistant to stomach acid
87
What is the role of IgE antibodies?
Defends against parasites
Causes anaphylatic shock and allergies
88
What is the role of IgD antibodies?
No known function
89
What are the five different processes carried out by antibodies?
* Neutralisation
* Secretion
* Oposinzation
* Complement activation
* Antibody-dependent cytotoxicity
90
What is secretion (related to antibody function)?
Antibody secretes mucous secretions that trap foreign antigen or pathogen
91
What is oposinzation (related to antibody function)?
An antibody increases the affinity for the pathogn and a phagocyte, allowing it to undergo phagocytosis
92
What is complement activation (related to antibody function)?
Antibodies can activate the complement system
93
What is antibody-dependent cytotoxicity (related to antibody function)?
Antibody stays bound to foreign antigen and allows it to be recognised by Tc cells so that apopotsis can occur
94
What is the primary immune response?
The first immune response
95
What is the secondary immune response?
The second immune response
96
Why is the secondary immune response much more rapid and larger than the primary immune response?
During the primary immune response, clonal selection occurs which produces memory cells. Memory cells continue to circulate even after the intial infection, ready to quickly divide if they recognise the same antigen. This allows more antibodies to be produced faster.
97
What are the two divisions of the adaptive immune response?
Passive
Active
98
What are the two types of processes that we gain BOTH passive and active immunity?
Natural methods
Artifical methods
99
What is active immunity?
When the individual creates own antibodies towards the pathogen
Reuslts in immunological memory
100
How can active immunity be naturally gained?
Individual being exposed to the infection
101
How can passive immunity be artificially gained?
Immunoglobulin therapy
Immune cells
102
How can active immunity be artifically gained?
Individual recieving a vaccine
103
What is passive immunity?
Individual recieves another individual's antibodies
104
How can passive immunity be naturally gained?
Mother passing her antibodies through the placenta to her baby
105
What are the advantages of passive immunity?
Immediate protection
Obtained quickly
106
What are the disadvantages of passive immunity?
No immunological memory
Protection is temporary
Can result in serum sickness - incoming antibody is recognised as foreign
Anaphylaxis
107
What are the advantages of active immunity?
Long term immunity
Immunological memory
108
What are the diasadvantages of active immunity?
Takes weeks to develop
