Responding to Antigens Flashcards
(79 cards)
1
Q
Antigen
A
An antigen is a unique molecule or part of a molecule that can initiate an immune response.
2
Q
Pathogen
A
Disease causing agent
3
Q
Disease
A
A physical or mental disturbance involving symptoms, dysfunction or tissue damage.
4
Q
Non-cellular pathogen
A
They require a host cell as they cannot reproduce outside a host cell
No metabolic cellular processes (whilst they have DNA or RNA they have no organelles to generate energy or proteins)
Not made of cells
5
Q
Non-cellular pathogen examples
A
Virus, prion
6
Q
Cellular pathogen
A
They do not require a host cell as they can reproduce outside a host cell
Can undertake metabolic cellular processes (they have DNA or RNA and they have the organelles to generate energy or proteins)
Made of cells
7
Q
Cellular pathogen examples
A
Bacteria, fungi, protozoa, parasite
8
Q
Draw a virus
A
9
Q
What genetic material can a virus contain?
A
single-stranded DNA, double-stranded DNA or RNA
10
Q
Prion
A
abnormal infectious proteins
11
Q
How do bacteria cause disease?
A
Bacteria release toxins
Bacteria population numbers are high due to rapid reproduction by binary fission.
This increases the volume of toxin made and so cause illness.
12
Q
Intracellular
A
Grow and reproduce inside of a host cell
13
Q
Extracellular
A
Grow and reproduce outside of a host cell
14
Q
Which pathogens are eukaryotic?
A
Protozoa, fungi, parasites
15
Q
Endoparasite
A
live inside a host
16
Q
Exoparasite
A
lives on the outside of a host
17
Q
Three types of barriers
A
Physical, chemical, microbiota
18
Q
Physical barrier
A
physical structures that prevent the pathogen from entering
19
Q
Examples of physical barriers
A
Intact skin, hairs
20
Q
Intact Skin
A
Intact skin is a physical barrier. This means that it prevents pathogens getting into the body.
21
Q
Hairs
A
Hairs are a physical barrier. This means that they trap foreign particles, like pollen and pathogens, preventing them from getting into the body.
22
Q
Chemical barrier
A
some type of secreted chemical that helps prevent the entry of a pathogen.
23
Q
Examples of chemical barriers
A
Stomach acid
Lysozymes in tears and saliva
Sweat
24
Q
Stomach acid
A
Stomach acid is a chemical barrier. This means that it is a concentrated acid that destroys pathogens if they get into our digestive system.
25
Lysozymes (tears + saliva)
Saliva and tears are a chemical barrier. This means that they contain lysozyme enzymes which break bacterial cell walls, causing the cells to burst
26
Sweat
Sweat is a chemical barrier. This means that it contains salts and fatty acids which act as bacterial inhibitors to prevent infection.
27
Microbiota barrier
The symbiotic microbiota outcompete pathogenic bacteria and other pathogens in animals. This means that it prevents the pathogens from establishing colonies and causing disease.
28
Examples of physical barriers in plants
Intact bark
Thick waxy cuticle
Thorns or trichomes (hair like structures)
Position of stomata
Formation of galls
29
Examples of chemical barriers in plants
Secretion of enzymes
Secretion of oils
Secretion of toxins
Odour chemicals
30
Microbiota barrier plants
Rhizosphere this means that naturally occurring bacteria outcompete the pathogenic bacteria in the soil by synthesising and releasing toxins.
31
Inflammation
Damaged cells/tissues release cytokines. These attract neutrophils to the site of infection and activate mast cells to release histamine.
Histamine causes vasodilation which is more blood flow to the area. This means that there will be more macrophages, neutrophils and dendritic cells brought to the site of infection and cause redness and an increase in temperature.
Histamine also causes an increase in membrane permeability. This means that more tissue fluid leaks out causing swelling and pain and means that the phagocytes can reach the tissues and help eliminate the pathogen by phagocytosis.
32
Innate leukocytes
Neutrophil, macrophage, dendritic cell (phagocytes)
Natural killer cell
Eosinophil
Mast cell
33
Innate immunity
Cells act broadly against actions of pathogens
Reaction from these cells are the same for ALL pathogens
Cells do not form a ‘memory’ of previous infections (there are no memory cells).
Cellular response is immediate.
34
Signs and symptoms of inflammation
Redness, heat, swelling, and pain
35
Cause of redness during inflammation
Histamine causes vasodilation which is more blood flow to the area.
36
Cause of heat during inflammation
Histamine causes vasodilation which is more blood flow to the area.
37
Cause of pain during inflammation
Histamine also causes an increase in membrane permeability. This means that more tissue fluid leaks out causing swelling which puts pressure on nerves creating pain
38
Cause of swelling during inflammation
Histamine also causes an increase in membrane permeability. This means that more tissue fluid leaks out causing swelling
39
Mast cell
Found in connective tissue and are activated by cytokines to release histamine
40
Histamine
Chemical messenger released by mast cells which binds to receptors on the cells lining blood vessels, causing them to dilate and become more permeable
41
Two roles of phagocytes
Phagocytosis and antigen presentation (dendritic cells and macrophages only)
42
Phagocytosis
Phagocytosis. This means that they recognise, engulf and digest foreign material, such as pathogens.
43
Outline the steps of phagocytosis
1. Phagocyte engulfs pathogen forming phagosome
2. Phagosome fuses with lysosome forming phagolysosome
3. Pathogen destroyed by digestive enzymes (lysozymes) in lysosome
4. Destroyed pathogen removed from the cell by exocytosis
44
Which cells have MHCI markers?
All nucleated cells
45
Which cells have MHCII markers?
Antigen presenting cells (dendritic cells, macrophages, B cells)
46
Antigen presentation
Antigen presenting cells (macrophage or dendritic). This means that they will move from the site of infection to the lymph node to present non-self antigens to T and B cells to initiate the adaptive immune response.
47
Neutrophils secondary function
releasing toxic products like hydrogen peroxide and cytokines through degranulation and NETs
48
Natural Killer Cells
Recognise non-self antigens on MHCI markers and release cytotoxic chemicals which destroy the virally infected or cancer cell.
49
Eosinophils
Large granulated cells containing various enzymes that recognize and destroy invading pathogens which are too large to be broken down by phagocytosis (parasites).
Contribute to inflammation and asthma
50
Complement proteins
Complement proteins form membrane attack complexes (MACs) on cells’ plasma membranes and cause the lysis of the cells.
Opsonisation occurs when complement proteins coat the cells and induce phagocytosis of the cells.
Complement proteins can also recruit other inflammatory cells that destroy the cells.
51
Interferon
Interferons are secreted by cells when they are infected with a virus. These interferons interact with receptors on neighbouring cells, causing them to undergo several changes that make them less susceptible to viral infection. This helps prevent the virus from spreading between cells.
52
Primary lymphoid organs
Bone marrow and thymus
53
Location of white blood cell production
Bone marrow
54
Purpose of lymphatic system in immunity
Act as a transport system for white blood cells
Site of antigen recognition (clonal selection, differentiation and expansion).
55
T cell maturation location
thymus
56
B cell maturation location
bone marrow
57
Fluid in cardiovascular system
plasma
58
Fluid in lymphatic system
lymph
59
Fluid surrounding cells
tissue fluid
60
How does lymph move
Movement- contractions of muscles and lymphatic vessels. Valves prevent back flow of fluid.
61
Location of clonal selection, differentiation and expansion
lymph node
62
T helper cell in humoral immune response
Detects non-self antigen from antigen presenting cell (dendritic cell / macrophage) which causes it to release cytokines to activate the naive B cell (clonal selection)
63
B cell
Detects non-self antigen from antigen presenting cell (dendritic cell / macrophage) AND cytokines from T-helper cell (clonal selection) allowing for it to divide by mitosis forming a B memory cell and a plasma cell (clonal differentiation and expansion)
64
Plasma cell
Secretes specific, complementary and free-floating antibodies.
65
B memory cell
Remains in circulation to provide long term immunity.
66
Humoral immune response
Humoral immune response
Clonal selection occurs. This means that the antigen presenting cell that has moved from the site of infection to the lymph node to present a non-self antigen on an MHCII marker to a B cell and T helper cell which causes the T helper cell to release cytokines to activate the naive B cell.
Clonal differentiation and expansion occurs. This means that the B cell divides by mitosis forming B memory cells and plasma cells.
The plasma cells then secretes specific, complementary and free-floating antibodies.
The B memory cells remains in circulation to provide long term immunity.
67
Clonal selection humoral immune response
Clonal selection occurs. This means that the antigen presenting cell that has moved from the site of infection to the lymph node to present a non-self antigen on an MHCII marker to a B cell and T helper cell which causes the T helper cell to release cytokines to activate the naïve B cell.
68
What activates (selects) a B cell
A specific and complementary antigen presented on an MHCII marker from an antigen presenting cell binds to their membrane bound antibody
Receive a cytokine signal from a selected T helper cell
69
Draw and label an antibody
70
Adaptive immune response cells
T helper cells, B cells, B memory cells, plasma cells, T cytotoxic cells, T helper memory cells, T cytotoxic memory cells
71
How does an antibody work?
Antibodies have specific and complementary antigen binding sites to the _____ antigens, so they attach to the antigen.
Agglutinate pathogens
Neutralise _____ toxins / _____ viruses.
Opsonise pathogens
Activate complement proteins.
These are all followed by phagocytosis of the pathogen.
72
Agglutination
Agglutination of _____pathogens occurs. This means that there are less pathogens circulating and makes phagocytosis of more pathogens easier.
73
Neutralisation
Neutralisation of _____ toxins / _____ virus occurs. This means that they become inactive and will reduce severity of disease.
74
Opsonisation
Opsonisation occurs by attaching to _____ pathogen. This means that phagocytosis is more likely as they have been marked for destruction.
75
Clonal selection cell-mediated immune response
Clonal selection occurs. This means that the antigen presenting cell /macrophage/dendritic cell moves from the site of infection to the lymph node to present a non-self-antigen on an MHCII marker to a T cytotoxic cell and T helper cell which causes the T helper cell to release cytokines to activate the T cytotoxic cell.
76
Cytotoxic T cells
Cytotoxic T cells have T Cell Receptors to detect non-self antigens on MHCI markers. This means that they can then release of perforins or cytotoxic chemicals that destroy the target cells or release cytokines to stimulate the death receptor pathway of apoptosis.
77
Cell mediated immune response
Clonal selection occurs. This means that the antigen presenting cell /macrophage/dendritic cell moves from the site of infection to the lymph node to present a non-self-antigen on an MHCII marker to a T cytotoxic cell and T helper cell which causes the T helper cell to release cytokines to activate the T cytotoxic cell.
Clonal differentiation and expansion occurs. This means that the T cytotoxic cell divides by mitosis forming an active T cytotoxic cell and a T cytotoxic memory cell.
The active T cytotoxic cell then releases cytotoxic chemicals to kill virally infected cells (once it recognises the non-self antigen on MHCI markers)
78
Similarities between natural killer cells and cytotoxic T cells
Recognizes non-self antigens presented on MHCI markers
Releases cytotoxic chemicals to kill a cell
Releases perforins to kill a cell
Releases death ligands to initiate apoptosis
79
Differences between natural killer cells and cytotoxic T cells
NKC = innate, non specific, does not produce memory cells
TC = adaptive, specific, produces memory cells
