Immunity Flashcards
1
Q
what is the non-specific response to disease?
A
the body has primary defences to stop pathogenic organisms from entering the body
2
Q
non-specific response to disease - skin
A
- non-pathogenic bacteria
- lactic acid and fatty acids secreted from sweat glands and sebaceous glands
- blood clot forms if skin is damaged
3
Q
non-specific response to disease - moist body surfaces
A
- eyes: tears contain lysozyme which damages and destroys bacteria
- mouth: saliva also contains lysozyme
- stomach: HCl destroys pathogens
4
Q
non-specific response to disease - mucus membrane
A
- protects digestive and respiratory tracts, stops pathogens making contact with epithelial lining
- layer of mucus covering the epithelium of these systems
5
Q
what are the secondary defences against pathogenic organisms?
A
- phagocytes
- white blood cells
- phagocytosis
6
Q
what is phagocytosis?
A
Engulf and digest foreign particles including pathogenic organisms
7
Q
what are the two types of phagocytosis?
A
Neutrophils & Macrophages
8
Q
How does phagocytosis occur in neutrophils?
A
- pathogen attached to phagocyte by antibody and surface receptors
- pathogen engulfed by infolding of phagocyte membrane
- lysosomes release lysin into phagosome
- harmless end products of digestion are absorbed
9
Q
phagocytosis in macrophages?
A
- macrophage moves towards pathogen
- pathogen engulfed by infolding of macrophage membrane
- lysosomes release lysins into phagosome to digest pathogen
- antigens from pathogen’s cell membrane placed on the membrane of the macrophage
- APC signals on immune response
10
Q
what does the macrophage become in phagocytosis?
A
antigen presenting
11
Q
where are phagocytes produced?
A
in bone marrow of long bones
12
Q
qualities of neutrophils
A
- Multi lobed nucleus
- 60% w.b.c.
- smaller
- short lived
- numbers increase during infections
- found in blood & squeeze through capillaries
13
Q
qualities of macrophages
A
- Large central nucleus
- Larger
- found in organs (e.g. lung, liver, kidney)
- long lived
- Become antigen-presenting cells (APC) and initiate`immune response’
14
Q
how do the macrophages travel in blood?
A
as monocytes, which then develop in body organs as macrophages
15
Q
immune response
A
is the specific response to a pathogen, which involves the action of lymphocytes and the production of antibodies
16
Q
antigen
A
a molecule, usually protein or glycoprotein, that is recognised as foreign by the immune system
17
Q
antigen-presenting cell
A
a cell that takes in a pathogen, or molecules from it, and displays the pathogens antigens in its plasma membrane where they may be encountered by a lymphocyte.
18
Q
antibody
A
a small protein secreted by B lymphocytes in response to a particular antigen and neutralises it’s effects.
19
Q
what are involved in a specific immune response?
A
B & T lymphocytes
20
Q
where do T lymphocytes develop?
A
in the bone marrow but finish maturing in the thymus gland
21
Q
how are the b lymphocytes developed?
A
in the bone marrow
22
Q
how are the lymphocytes stimulated into action?
A
by antigens
23
Q
how many lymphocytes in the blood?
A
at least a million
24
Q
what happens as the lymphocytes mature and where are they placed?
A
- produce small quantities of antibodies
- antibodies placed into the plasma membrane of the lymphocytes
25
what do the antibodies act as?
They then act as receptors and are able to bind with a particular antigen if it appears in the body
There will be at least one lymphocyte that has a complementary antibody receptor to the antigen
26
what happens as B lymphocytes mature?
they develop the ability to produce just one specific antibody molecule with a specific receptor site.
27
how are B lymphocytes stimulated?
B lymphocytes are stimulated when it meets antigens in the blood or an APC – clonal selection.
28
how do B cells divide?
B cell divides repeatedly by mitosis producing many clones – clonal expansion.
29
what do clone cells sometimes differentiate into?
plasma cells
these develop extra protein-making organelles
30
where are antibodies found and why?
Antibodies cannot pass into cells but are found in blood, lymph and on surfaces of mucus membranes e.g. in the lungs.
31
what can B clone cells also differentiate into?
memory cells, these do not produce antibodies
32
what do the memory cells do?
They remain in circulation for a long time and respond very quickly if the same antigen enters the body again.
33
what are antibodies made up of?
4 polypeptide chains held together by disulphide bridges.
Y shaped with 2 distinct regions:
constant and variable
34
constant region
same in all antibodies. Enables attachment to phagocytic cells and helps in process of phagocytosis
35
variable region
has a specific shape that varies from one antibody to another. Results from change in amino acid sequence. Ensures antibody can only attach to correct antigen
36
hinge region
allows flexibility of branches to allow attachment to more than one antigen.
37
what are the effects of an antibody?
neutralisation or agglutination
38
neutralisation
cancels out the effect/ability of a substance or cell
39
agglutination
sticks substances/cells together
40
what does an antigen bind to?
a specific antigen
41
types of neutralisation
- bind to toxins produced by bacteria
- Some bind to antigens on the bacterial cell stopping it binding to the host cell
42
agglutination types
Some attached to more than one bacterial cell at a time causing them to clump together
42
when is the T lymphocyte stimulated?
when it meets an antigen on an APC such as a macrophage or body cell invaded by a virus
43
what is a Helper T cell?
The T lymphocyte must have the complementary antibody on its cell surface to match the antigen – clonal selection.
44
clonal expansion of the Helper T cell (Th) occurs producing
- more Th
- killer T cells (Tk)
- memory T cells (Tm)
- suppressors T cells (Ts)
45
what does the corned Th also secrete?
cytokines
46
what do cytokines do?
Cytokines stimulate other cells to fight against the invaders:
- Macrophages to carry out phagocytosis
- B lymphocytes specific to the antigen to divide rapidly producing plasma cells
47
what do the killer T cells do?
The Killer T cells (Tk) attach to any cells displaying its complementary antigen.
They completely destroy the cell they have become bound to by secreting chemicals such as hydrogen peroxide.
48
What do suppressor T cells do?
Suppressor T cells (Ts) stop the immune response when the pathogens have been destroyed.
49
what do memory T cells do?
Memory T cells respond if the same antigen ever invades again.
50
When a new pathogen enters the body, it takes time for:
- Lymphoctyes to find & bind with the pathogen
- Clonal expansion
- Plasma cells to secrete antibodies or Tk cells to destroy infected cells.
50
what happens when the body pathogen appears? primary response
- During this time the pathogen has opportunity to divide and become established within the body tissues.
- The infected person will show symptoms of the disease & it can take days or weeks before the lymphocytes have destroyed the pathogen.
51
if the person survives the pathogenic infection? secondary response
- memory cells would have been produced and remain in circulation for a long time
- If the pathogen is encountered again there is a faster and more effective response, killing the pathogen before it causes any symptoms
52
primary and secondary response graph
53
what are the two types of immunity?
- active
- passive
54
what is active immunity?
When the body’s defences (i.e. lymphocytes) are activated by antigens on the surface of pathogens.
55
natural active immunity examples
Natural active immunity occurs when the body fights off an infection.
56
artificial active immunity examples
Artificial active immunity occurs when people are VACCINATED against infection.
57
what is passive immunity?
When defence against disease is provided in the form of antibodies or antitoxins.
58
examples of natural passive immunity
Natural passive immunity when antibodies from the mother pass across the placenta to provide protection until the infant’s own immune system can take over
59
examples of artificial passive immunity
Artificial passive immunity when a vaccination provides an immediate source of antibodies.
60
what is a vaccine?
A preparation of an antigen for a specific infectious disease. It is injected or given by mouth.
61
what does a vaccine stimulate?
A vaccine stimulates a primary response, so it takes time to gain immunity.
62
what are boosters given?
Boosters are given to develop the secondary response.
63
what is smallpox?
the first disease to be eradicated, caused by a virus
64
how did smallpox become eradicated?
- Only one strain.
- Did not infect animals.
- Diagnosis was easy.
- Every one infected developed symptoms.
no reservoir of virus to cause re-infection
65
how was smallpox vaccine successful?
- A live vaccine was used so boosters were not necessary
- Was freeze dried so could be used in the tropics
- Only one vaccine needed and was cheap to produce
66
why are some diseases difficult to eradicate?
- Some pathogens exist in many strains due to mutation e.g. influenza
- Pathogens can invade the human gut where the immune system does not work effectively e.g. cholera
- It is difficult to develop vaccines that are caused by eukaryotic organisms e.g plasmodium, because they have many genes that code for cell surface antigens. Plasmodium lives inside cells so it is difficult for antibodies to reach them.
67
how are measles caused?
- caused by a virus, affects young children primarily
- In developing countries, very difficult to vaccinate soon after birth when they are most vulnerable.
68
what are monoclonal antibodies?
- All identical
- Made by one type of plasma cell
- Are specific to one epitope ( a specific part of an antigen)
- Are highly specific
69
how do you make monoclonal antibodies?
- Grow 1 clone of B cells in culture (animal) and collect antibodies
- B cells do not divide in culture therefore fuse with cancer cells
- hybrid cells created, hybridomas, grow and divide to secrete antibodies
70
list 7 uses of monoclonal antibodies?
- Blood typing for transfusions
- Tissue typing for transfusions
- Identification of pathogens
- Pregnancy test
- Identification and location of cancers
- Clarification of leukaemia's
- Following progress of HIV infection
71
what are the advantages of using monoclonal antibodies in diagnosis?
- Cheap;
- Easy to use;
- At home/clinic/surgery;
- Rapid diagnosis
- High degree of specificity;
72
advantages of natural active immunity?
long-term immunity
73
disadvantages of natural active immunity?
Immune response takes time; protection not immediate; symptoms develop and may be fatal
74
advantages of artificial active immunity?
Long term immunity without suffering from the disease
75
disadvantages of artificial active immunity?
Immune response takes time; protection not immediate
76
advantages of natural passive immunity?
Immediate protection from common diseases that the mother has had or been vaccinated against
77
disadvantages of natural passive immunity?
Short-term immunity; antibodies destroyed; no memory cells produced
78
advantages of artificial passive immunity?
Immediate protection to a specific disease e.g. tetanus
79
disadvantages of artificial passive immunity?
Short-term immunity; antibodies are destroyed; no memory cells produced
