4.1.1 Communicable diseases, disease prevention and the immune system Flashcards
1
Q
What is a disease?
A
An illness or disorder of the body or mind that leads to poor health.
2
Q
What are communicable diseases?
A
Diseases are caused by pathogens which can be passed from infected to infected people.
3
Q
Give some examples of communicable diseases.
A
- Cholera
- Malaria
- HIV/Aids
- Tuberculosis (TB)
4
Q
Give some examples of non communicable diseases.
A
- Lung cancer
- Sickle cell anaemia
- Cystic fibrosis
5
Q
Name four groups of pathogens that can cause communicable diseases.
A
-Bacteria
-Viruses
-Protosista
-Fungi
6
Q
Give an example of a communicable disease caused by bacteria in plants.
A
Ring rot.
7
Q
Give an example of a communicable disease caused by bacteria in humans.
A
Tuberculosis
8
Q
Give an example of a communicable disease caused by viruses in plants
A
Tobacco mosaic virus
9
Q
Give an example of a communicable disease caused by viruses in humans
A
HIV/Aids
10
Q
Give an example of a communicable disease caused by protostista in plants
A
Potato blight
11
Q
Give an example of a communicable disease caused by protosista in humans
A
Malaria
12
Q
Give an example of a communicable disease caused by fungi in plants
A
Black sigatoka
13
Q
Give an example of a communicable disease caused by fungi in humans
A
Athletes foot
14
Q
What are the filaments in the body of fungi called?
A
Hyphae
15
Q
How is malaria spread?
A
A female mosquito feeds on a human who is infected with malaria, then when she takes up their blood she will also take up the pathogen and so the next person she feeds on will get malaria.
It can also be transferred via blood transfusion or across the placenta to babies.
16
Q
Structure of viruses.
A
Viruses do not have a cellular structure as they infect host cells.
17
Q
How do pathogens maintain survival?
A
They must be able to successfully transfer from host to host.
18
Q
What are the two types of disease transmission?
A
Direct and indirect.
19
Q
Define direct transmission.
A
Transmission from one host to another host.
20
Q
How can pathogens transmitted directly?
A
-physical contact
- close proximity.
-Spores
-Sexual intercourse
21
Q
What are spores?
A
Reproductive structures that are dispersed via wind or water.
22
Q
How is HIV/Aids transmitted?
A
direct exchange of body fluids.
E.g:
* Sexual intercourse
* Blood donation.
* Sharing of needles used by intravenous drug users.
* From mother to child across the placenta, from breast milk and during birth.
23
Q
Give an example of diseases that can be directly transmitted.
A
-HIV/Aids
-Tuberculosis
24
Q
How is tuberculosis transmitted?
A
When uninflected people inhale droplets from infected peoples cough or sneeze.
TB therefore spreads in places with severe overcrowding.
One form of TB can be transmitted in contaminated meet and unpasteurised milk however this is only usually the case in developing countries.
25
What is indirect transmission?
When a second organism (a vector) that is unaffected by the pathogen transfers it to a new host.
26
Give an example of disease which are transmitted indirectly.
Malaria
27
What is the vector in the disease malaria?
The female mosquito.
28
How do resistance and immunity differ?
Resistance is different to immunity as when resistant individuals are exposed to the pathogen for the first time they do not develop the disease and suffer no symptoms.
However, an immune individual is someone who has been previously infected with the pathogen, suffered the symptoms and recovered. Therefore they are unlikely to develop symptoms of the disease when exposed to the pathogen again.
29
State some factors affecting disease transmission.
-Proximity
-Poverty
-Culture
30
Why does high proximity with others lead to increased disease transmission?
Places with high population densities are more likely to have high infection rates e.g cities and schools.
31
Give an example of how high proximity with others leads to increased disease transmission?
-Tuberculosis transmission is high where people have to sleep in confined quarters e.g poor housing and homeless shelters.
Farmers who grow a large number of plants in a small area and leaves touch each other make the transmission of pathogens very easy.
32
Why do high poverty levels lead to increased disease transmission?
Those who live below the poverty line usually live in areas with crowded housing and no sewage systems with poor sanitation. And they may have less access to hygiene products.
33
Give an example of how high poverty levels leads to increased disease transmission?
Diseases such as thyphoid, cholera and polio spread when human faecal matter enters and contaminates drinking water.
34
Why could cultural differences lead to increased disease transmission?
In some parts of Africa, it is religious and a cultural tradition to touch and kiss the dead. This was a major problem when Ebola was spreading in Africa.
35
What is a endemic?
A disease that is always present in a population.
36
What is a epidemic?
When there is a large increase in the number of cases of a disease.
37
What is a pandemic?
An epidemic that occurs on a large scale and crosses international boundaries.
38
What are passive defence mechanisms?
Defence mechanisms that are always present. E.g physical barriers.
39
What are active defence mechanisms?
Defence mechanisms which are activated when a plant is invaded by a pathogen. E.g depositing callose.
40
Give some examples of passive defence mechanisms in plants?
-Waxy cuticle
-Cellulose cell wall
-Closed stomata
-Bark
-Casparian strip
41
How does a plants waxy cuticle act as a physical barrier for pathogens?
Prevents pathogens from entering as well as prevents water collection on a leaf which prevents water-borne diseases from spreading.
42
What are some chemical defences in plants?
-Sticky resin found in bark
-Some plants produce chemicals which destroy the membranes of pathogens.
-Phytoalexins inhibit the growth of pathogens.
43
What is the role of the first line of defence in animals?
To prevent the entry of pathogens.
44
Give some examples of the first line of defence against pathogens.
-Skin
-Mucous membranes
-Expulsive reflexes
-Chemical secretions
45
How does the skin act as a first line of defence against pathogens?
-Posses an outer layer of dead, dry, hardened cells filled with keratin.
This is a physical barrier to protect pathogens
*There are secretions of sebum which contain fatty acids and have anti-microbial properties.
Evaporation of sweat from skin leaves behind a salt residue.
46
Where are mucous membranes found?
The gut, airways and reproductive systems.
47
How do mucous membranes act as a first line of defence against pathogens?
Mucous membrane consist of epithelial cells and mucus-secreting cells like goblet cells.
Mucus contains lots of glycoproteins with long carbohydrate chains. These chains are what make mucus sticky.
Viruses, bacteria, pollen and dust float around the air and mucus in the airways can trap these particles and move them by cilia.
48
How do expulsive reflexes act as a first line of defence against pathogens?
When a pathogen irritates the lining of an airway it can trigger an Expulsive reflex; a cough or a sneeze.
These result in a sudden expulsion of air and this air contains the secretions from the respiratory tract as well as the foreign particles which have entered it.
49
How do chemical secretions act as a first line of defence against pathogens?
Lysozymes are antimicrobial enzymes that break down the cell wall of bacteria.
-They are found in blood, sweat, tears, breast milk.
-Hydrochloric acid is produced by the cells that line the stomach.
The acid creates a low pH which helps to kill any bacteria that has been ingested.
50
What are lysozymes?
antimicrobial enzymes that break down the cell wall of bacteria.
51
Where are lysozymes found?
Blood, sweat, tears and breast milk.
52
What acid is found in the stomach?
Hydrocholoric (HCL)
53
Name some responses which make up the second line of defence in animals.
-Blood clotting
-Inflammation
-Wound repair
-Phagocytosis
54
How does blood clotting occur?
A break in the mucous membrane or skin membrane causes the release of molecules that trigger a chemical cascade which results in blood clotting.
55
Why is blood clotting beneficial to the body in the second line of defence?
It prevents excess blood loss and the entry of pathogens.
56
How does inflammation occur in the second line of defence?
Inflammation is a local response to infection and tissue damage and occurs via chemical signalling molecules which cause the migration of phagocytes to the tissue.
Body cells called mast cells respond to tissue damage by secreting histamine and cytokines which trigger a response.
57
What type of cells secrete histamine and cytokines?
Mast cells.
58
How does a scab work?
Under a scab stem cells divide by mitosis to heal a wound.
59
What are histamines?
Chemicals created in the body which dilate blood vessels to increase blood flow (causing localised heat and redness). The leaky capillaries allow fluid to enter the tissue and create swelling so white blood cells can fit through.
60
Role of cytokines
Attract phagocytes for phagocytosis.
61
What are phagocytes?
White blood cells produced from bone marrow to remove dead cells and invasive microorganisms as well as carry out the non specific immune response.
62
What are the three types of phagocytes?
Neutrophils
Macrophages
Dendritic cells
63
Structure of a neutrophils nucleus.
Lobed
64
Role of neutrophils
Chemicals released by pathogens and chemicals that are produced by body cells under attack (e,g histamines) attract neutrophils to the site where the pathogen is located and move towards it. During an infection, they are released in large numbers.
One attached to a pathogen, the cell surface membrane of the neutrophil extends out and around the pathogen, engulfing it and trapping the pathogen within a phagosome.
The neutrophil secretes digestive enzymes into the vacuole which destroys the pathogen.
After engulfing the pathogen, the neutrophil dies.
65
Where are dendritic cells found?
Anywhere in the body.
66
What are dendritic cells?
Large cells with length extensions.
67
Are neutrophil cells long or short lived?
Short lived
68
Are macrophages long or short lived?
long
69
Role of macrophages
Macrophages carry out endocytosis however they do not destroy the pathogen completely but cut them up so that they can display the pathogens antigens on their surface and these antigens can be recognised by lymphocytes.
70
What type of cells are considered to be the 'third line of defence'
Lymphocytes
71
What are lymphpcytes?
A type of white blood cell.
72
Two main types of lymphocytes.
T cells
B cells
73
Where are T cells made and matured?
Made in bone marrow but mature in thymus gland.
74
Where are B cells made and matured?
Made and mature in bone marrow.
75
Role of T lymphocytes?
They gain specific cell surface receptors complementary to different antigens.
76
T cells can differentiate into different types of T cells known as:
T helper cells
T killer cells
T regulator cells
77
How do macrophages and T cells work together?
Macrophages engulf pathogens and present their antigens on their own surface to become antigen-presenting cells. T cells with the complementary receptors bind to the antigen-presenting macrophage which actives the T cell to produce clones which have specific responses.
78
What do T helper cells do?
Release chemical signalling molecules known as interleukins which cause phagocyte activity to increase.
79
What do T killer cells do?
Patrol the body in search of antigen presenting body cells and secrete substances that kill infected body cells.
80
What do t regulatory cells do?
Suppress other cells once the body is cleared of the pathogen
81
What do T memory cells do?
Remain in the blood meaning that if the same antigen is encountered again clonal selection will occur quicker
82
What are B cells?
They gain specific surface receptors (antibodies). B cells with complementary antibody receptors bind to antigens on APC's.
83
What is clonal expansion?
When activated b cells divide by mitosis to produce larger numbers of B cells.
84
Types of b cells
plasma cells
b memory cells
85
What are the two types of the immune response?
Primary response and secondary response
86
What is the primary immune response?
exposure to a newly encountered pathogen.
87
Why is the primary immune response slower?
there are not many B lymphocytes that can make the antibody needed to bind to the pathogen. Eventually the body will create enough antibodies to overcome the infection and in this time the person will show symptoms of the disease.
88
What is the secondary immune response.
Exposure to a previously encountered pathogen.
89
How does the secondary immune response work?
If the same foreign antigen is found in the body the second time, the B memory cells recognise the antigen and the immune response is much faster. B memory cells divide very quickly into plasma cells and more memory cells so that the infection can be destroyed and removed before the pathogen population is too much and the symptoms of the disease are developed.
90
State some functions of antibodies.
-Directly attacking pathogens
-Anti-toxins by binding to pathogen produced toxins and neutralising them.
-attach to bacteria to make them readily identifiable to phagocytes (opsonisation)
-Attach to flagella of bacteria to make then less acttive
-Agglutinins (pathogens clump together).
91
What are opsonins?
When antibodies attach to bacteria to make them readily identifiable for phagocytes.
92
What are agglutinins?
When antibodies cause pathogens to clump together so that phagocytes can engulf a lot of pathogens at the same time.
93
What is active immunity?
When a pathogen enters the body triggering a specific immune response via natural exposure to the microbes or artificial vaccinations.
94
What is passive immunity?
Immunity acquired without an immune response.
95
State an example of artificial passive immunity.
When people are given an injection/transfusion of antibodies from someone else.
96
State an example of natural passive immunity.
Foetuses receiving antibodies across placenta or in breast milk
97
State an example of natural active immunity.
Exposure to pathogen
98
State an example of artificial active immunity.
Vaccines
99
What is an autoimmune disease?
Where the body attacks itself and the immune system damages body cells as a result.
100
State some examples of autoimmune diseases.
-Lupus
-Rheumatoid arthiritis
101
Two main types of vaccines.
-Live attenuated
-Inactivated
102
How do vaccines cause long-term immunity?
They cause memory cells to be created so the immune system remembers the antigen and when re-encountered produces antibodies against it.
103
Define herd immunity.
when a sufficiently large proportion of the population has been vaccinated (and are therefore immune) which makes it difficult for the pathogen to spread within that population to those who are not vaccinated.
104
What is ring immunity?
People living or working near a vulnerable person are vaccinated in order to protect them from catching and transmitting the disease. The vaccinated individuals do not spread the pathogen onto others so vulnerable individuals “within the ring” are protected as the people they interact with will not have the disease.
105
What is a live attenuated vaccine?
contain whole pathogens that have been weakened
106
Advantage of live attenuated vaccines.
These types of vaccines trigger a strong and long lasting response.
107
Disadvantage of live attenuated vaccines.
They can be unstable for people with weak immune systems as they may multiply faster than they can carry out an immune response
108
What is an inactivated vaccine?
Contains a whole dead pathogen
109
Disadvantage of an inactivated vaccine.
May need boosters to keep up.
110
What type of pathogen do antibiotics treat?
Bacteria
111
Why are mutations in bacteria a problem?
When the population is treated with this antibiotic, some will just not die as they are resistant.
This means that the resistant bacteria can now reproduce with less competition from the non-resistant bacteria which are now dead.
Therefore the genes for antibiotic resistance are passed onto their offspring.
Overtime, the whole population will be antibiotic-resistant and this is an example of evolution by natural selection.
112
Two ways which bacteria inherit antibiotic resistance:
-Vertical transmission
-Horizontal transmission
113
What is vertical transmission?
Bacteria reproduce asexually by binary fission. If one bacteria has the mutant gene all of its descendants will have this resistance.
114
What is horizontal transmission.
Plasmids (small rings of DNA) often contain anti-biotic resistant genes.
These plasmids are frequently transferred between bacteria.
This occurs during conjugation (when a thin tube forms between two bacteria to allow the exchange of DNA).
A bacterium containing a mutating gene that gives it antibiotic resistance could pass this gene onto other bacteria.
This enables antibiotic resistance to spread within or between bacterial populations.
115
Give some ways to reduce the human population becoming resistant to antibiotics.
-Only prescribing antibiotics when necessary.
-Ensuring patients complete courses of antibiotics.
-Rotating which antibiotics are being used.
-Holding back some antibiotics as a last resort.
-Antibiotics not being used to viral infections.
-Investing in antibiotic research projects.
116
difference between immunisation and vaccination.
Vaccination is the process of being injected by antigens (the vaccine) and immunisation is the processes by which you develop immunity (from the vaccine)
117
difference between immunisation and vaccination.
Vaccination is the process of being injected by antigens (the vaccine) and immunisation is the processes by which you develop immunity (from the vaccine)
118
which cells in the body are attacked if you have lupus?
connective tissue
119
which cells in the body are attacked if you have rheumatoid arthritis?
Joints
120
why does the flu vaccine change every year?
antigens on the surface of the influenza virus change regularly forming new strains
121
give two examples
of antibiotic resistant bacteria
MRSA- serious wound infections.
Clostridium difficile- inhibits digestive system.
