Microorganisms and disease Flashcards
(91 cards)
1
Q
What is a pathogen?
A
A microorganism that causes disease
2
Q
How does the invasion of a pathogen lead to infection?
A
If it colonises the tissue of the host
3
Q
What is it known as when a pathogen is transferred from one host to another?
A
Transmission
4
Q
What is the 1st line of defence?
A
Physical barriers
5
Q
What are physical barriers known as?
A
The surface interface
6
Q
What do pathogens need to do in order to cause disease?
A
Penetrate the host’s interface
7
Q
What are the surface interfaces of the human body?
A
Skin, eyes, ears, nose, mouth, digestive system, lungs, anus, vaginal area and urethra
8
Q
How do ears protect against pathogens?
A
They have wax to trap them
9
Q
What are the barriers of the eye?
A
Eyelashes
tears
Its 2 layers
10
Q
How do eyelashes protect the eye?
A
They are a physical barrier that will trap particles but it’s unlikely to prevent pathogen entry
11
Q
How do tears protect the eye?
A
- They have antiseptic properties that kill pathogens
- Prevents the eye drying which prevents cracking which could make it vulnerable to infection
12
Q
What are the 2 layers of the eye?
A
The conjunctiva and the cornea
13
Q
How do the 2 layers of the eye protect the eye?
A
They are physical barriers
14
Q
Why is skin difficult to penetrate?
A
It is thick and multilayered(has strata = layers)
15
Q
What are the top layer of skin cells?
A
Dead
16
Q
What are the skin cells near the top layer filled with?
A
Keratin protein - provides strength and a waterproof barrier
17
Q
What do we have next to the hair follicles and what do they produce?
A
Sebaceous glands - produce oils that have antibacterial properties and keep the skin supple
18
Q
What does the skin have and what do they produce?
A
They have sweat glands which produce sweat
19
Q
How does sweat protect against pathogens?
A
It has antibacterial properties and keeps the skin moist
20
Q
What happens if you have a cut or cracked skin?
A
The skin is vulnerable to pathogen entry
21
Q
What happens when you have a cut and blood is exposed in terms of preventing pathogen entry?
A
- Protein fibres build up by the cut
- Platelets form clots
- WBCs are nearby to fight infection
22
Q
What are produced by damaged cells in the skin and what do they do?
A
Histamines - cause inflammation and raise the temperature which help prevent the entry of pathogens
23
Q
What forms over the cut in the skin to help the skin underneath to heal?
A
Scabs - form a waterproof barrier and physical barrier
24
Q
How does the nose protect against pathogens?
A
Has mucus produced by goblet cells that traps pathogens
25
How do trachea and bronchi protect against pathogens?
- Goblet cells that produce mucus and traps pathogens
- Cilia on ciliated epithelium waft mucus away
26
How does the mouth protect against pathogens?
Produces saliva that contains antiseptic chemicals which will start the process of destroying any pathogens
27
How does the stomach protect against pathogens?
pH 2 environment - has hydrochloric acid which kills bacteria
28
How does the vaginal area and uterus protect against pathogens?
It has an acidic environment
29
How does the urethra protect against pathogens?
Urine contains toxic chemicals so quite hard for pathogens to survive
30
How can bacterium enter the body?
Via the fluids
- Blood
- Lymphatic fluid
- Tissue fluid
31
What is the difference between non-specific mechanism and specific mechanism?
Non-specific do not distinguish between one pathogen and another whereas specific does distinguish between different pathogens
32
Which defence mechanism is used in non-specific defence?
Phagocytosis - this is always present
33
What is the response of specific mechanism like?
Less rapid but it gives longer lasting immunity
34
What does a phagocyte contain that helps destroy pathogens?
Lysosomes - contains hydrolytic enzymes
35
What does the phagocyte need to do in order to initiate phagocytosis?
It will try to identify antigens on the surface of the structure (e.g. cell or virus)
36
What will the phagocyte do if it does not recognise the pathogen?
It will attach itself to the pathogens attachment proteins
37
What does the phagocyte do after it has attached to the pathogen?
Cell membrane of the phagocyte extends and engulfs the pathogen
38
What is the pathogen engulfed in once it has been engulfed by the phagocyte?
It is engulfed in a phagosome (vesicle containing the pathogen)
39
What will the lysosomes inside the phagocyte due to the phagosome that has formed?
They will fuse with the phagosome and the hydrolytic enzymes will fuse in and hydrolyse/destroy the pathogen
40
What happens to the dead pathogen inside the phagocyte?
Its component parts are either exocytosed into the bloodstream or they diffuse into the phagocyte to be used
41
What does the phagocyte do with the antigens of the pathogens it has just destroyed?
It displays the antigens on its surface to illicit a specific immune response - called an antigen presenting cell
42
What does phagocytosis cause at the site of infection?
Inflammation
43
Why does phagocytosis cause inflammation at the site of infection?
As a result of histamines - produced due to cellular damage
44
What do histamines do to blood vessels?
Dilate them which speeds up delivery of phagocytes to a site of infection
45
What will the swollen area around a cut contain?
Dead pathogens and phagocytes (pus)
46
Where are B-cells and T-cells made and what are they actually?
In the bone marrow
B-lymphocytes and T-lymphocytes
47
What can phagocytes not do in that we need a specific immune response?
- Identify infected cells
- Have no memory of pathogens they have destroyed
- Only come across pathogens by chance
- Cannot neutralise toxins
48
Where do B-cells mature?
In the bone marrow
49
What is the responsibility of the B-cells?
Produce antibodies and antitoxins which will be put into all fluids of the body
50
What is the action of B cells known as?
Humoral response
51
Where do T-cells mature?
Thymus gland and then are housed in other glands of the immune systems
52
What is the responsibility of T-cells?
Cell on cell response - cell mediated response
53
What are the 2 types of T-cells we need to know?
T-helper cells and the cytotoxic T cell (killer T cell)
54
What is important about the shape of antigens and toxins?
They have the same 3D shape (protein)
55
What is it called when antigens and toxins have the same shape?
Antigenic
56
What could an antigen presenting cell (APC) be?
Phagocyte or cell of body that has been infected - it has the pathogens antigen on its surface
57
What does an APC release?
Chemicals that brings T-cells to the area - there are a variety of T-helper cells with a variety of antigens on their surface
58
What will the T-helper cells that have come to the area with an APC do?
One of them will have a complimentary antigen to the pathogens antigen on the APC and binds (lock and key)
59
What do T-cells do once they have bound to an APC?
Coordinate the rest of the specific immune response
60
What does the T-helper cell that has bound to the APC release?
Cytokines (chemical messages) - they attract other specific cells to the area
61
What is brought to the area where T-helper cells have released cytokines?
A variety of B-cells - they have different antigens on their surface
62
What do the B-cells that come to the area where T-cells have released cytokines do?
They see which one has a complimentary antigen to the T-helper cell and then this one binds to it
63
What does the B-cell do after it has bound to the T - helper cell?
These undergo mitosis to produce genetically identical copies (clonal expansion)
64
Can B-cells produce antibodies and antitoxins as soon as they bind to the T-helper cell that is bound to the APC?
No - they need to go through a stage of specialisation and form plasma cells and antitoxins
65
What happens once the B-cells specialise and form plasma cells?
They produce antibodies and antitoxins
66
What do some of the B-cells specialise into apart from plasma cells?
Into memory B-cells
67
How are memory B-cells able to fight against a pathogen more efficiently?
They can respond directly with the antigen presenting cell
68
What happens when memory B-cells respond with the antigen presenting cells?
They will undergo clonal expansion and specialise - into plasma cells which then produce antibodies and antitoxins
69
Why are memory B-cells more efficient at fighting pathogens?
- Faster response
- Produce a higher concentration of antibodies and antitoxins and these stay at a higher concentration for a long period of time
70
What is different about the antibodies of memory B-cells?
They have a greater affinity for the pathogens antigen
71
What else is brought to the area where T-helper cells release cytokines (not B-cells)?
Cytotoxic T-cells - with varying antigens on their surface
72
What do the Cytotoxic T-cells that come to the area where T-cells have released cytokines do?
One will have a complimentary antigen to the T-helper cell and will bind to it
73
What will the cytotoxic T-cell that has bound to the T-helper cell undergo?
Mitosis - clonal expansion
74
What do the cytotoxic T-cells do once it has found the infected cell?
Binds to the antigen and will then produce chemicals/lytic enzymes that will destroy the pathogens inside
75
Are memory T-cells also formed?
Yes
76
What do memory T-cells do in order to fight pathogens?
They can bind directly with an APC, undergo clonal expansion and will fight the infected cells
77
What do antibodies do?
Bind to the pathogens antigen
78
What do antibodies cause pathogens to do and what is this called?
They clump them together - called agglutination
79
What can't pathogens do when they are clumped together?
- Can't spread so minimises cellular damage
- Prevents them entering into cell
- No binary fission
80
What can antibodies do to the pathogen directly?
Can cause lysis(breakdown) to the pathogen
81
How is the agglutination of the pathogens destroyed?
Phagocyte comes and engulfs it and destroys it
82
What is a passive response?
When no memory-cells are made
83
What is an active response?
When memory cells are made and there is an immune response
84
What kind of proteins are antibodies?
Globular
85
What are antibodies made up of?
4 polypeptide chains
- 2 heavy chains
- 2 light chains
86
Which part is the same in most antibodies?
The 4 polypeptide chains
87
What are the polypeptide chains in antigens held together by?
Disulphide bonds
88
What part of the antibody is the complimentary part?
The variable regions on the top
89
How do we have different variable regions in different antibodies?
The primary order of amino acids in the polypeptide chain is different in different variable regions
90
What do antibodies have that allow them to attach to more than one pathogen at a time?
Spatial flexibility
91
How do antibodies have spatial flexibility?
They have a hinge region in the polypeptide chain
