Communicable Diseases and the Immune Response Flashcards
(243 cards)
1
Q
What parts of the plant does Ring Rot damage?
A
Leaves, tubers and fruit
2
Q
What causes a communicable disease?
A
A pathogen
3
Q
What are the 4 main types of pathogen?
A
- Bacteria 2. Viruses 3. Protoctista 4. Fungi
4
Q
What does a vector do?
A
Carry pathogens from one organism to the other
5
Q
How are communicable diseases in plants spread?
A
Directly plant-to-plant
6
Q
What proportion of bacteria cause communicable disease?
A
Only a small proportion
7
Q
What is a bacterial cell wall mostly made up of?
A
Peptidoglycan
8
Q
What is the basic structure of any virus?
A
Some genetic material (either DNA or RNA) surrounded by a protective protein coat
9
Q
What is the mechanism of infection of a virus?
A
They attach to the cell and inject their genetic material, which takes over the biochemistry of the host cell to make more viruses by inserting itself into the host DNA, until so many are made that the host cell is lysed (bursts) and the new viruses are released
10
Q
What proportion of naturally occurring viruses are pathogenic?
A
All of them
11
Q
How many other types of organism do viruses infect?
A
Every other type of organism, including other viruses
12
Q
What is a bacteriophage?
A
A virus which attacks a bacteria
13
Q
Are protoctista eukaryotic or prokaryotic?
A
Eukaryotic, with a wide variety of feeding methods
14
Q
What proportion of protoctista are pathogenic?
A
Only a small percentage, most are harmless
15
Q
What are fungi a major problem for?
A
Some plants- they tend not to be a major problem for animals
16
Q
Are fungi eukaryotic or prokaryotic?
A
Eukaryotic
17
Q
Are protoctista unicellular or multicellular?
A
Unicellular, although they can group into colonies
18
Q
Are fungi unicellular or multicellular?
A
Usually multicellular, with the exception of yeasts
19
Q
How do fungi feed?
A
Many are saprophytes, but the pathogenic ones are parasites and eat living organisms. They can’t photosynthesise, so digest food outside of their cells before absorbing the nutrients
20
Q
What do saprophytes feed on?
A
Dead and decaying matter
21
Q
What part of a plant do many plant fungal diseases affect?
A
The leaves, stopping the plant photosynthesising and killing it rapidly
22
Q
How do fungi reproduce?
A
They produce millions of spores, which can spread huge distances and spread their disease quickly among crops
23
Q
What organelles does yeast have?
A
Nucleus, mitochondria, cell membrane and a permanent vacuole
24
Q
What are the two main pathogenic modes of action?
A
- Damaging host tissue directly 2. Producing toxins which damage host tissue
25
What is the mechanism of action of most pathogenic bacteria?
They produce toxins which poison/damage the host cells in some way
26
What organisms does tuberculosis affect?
Humans, cows, pigs, badgers and deer
27
What type of pathogen is tuberculosis caused by?
Bacteria
28
People suffering from what other disease are more likely to suffer from tuberculosis?
HIV/AIDS
29
How is TB cured and prevented?
Cured with antibiotics, prevented by vaccination or better living standards
30
How is TB spread in humans?
Droplet infection
31
What is the mechanism of TB?
It damages and destroys lung tissue and suppresses the immune system so that the body is less able to fight off other diseases
32
How is bacterial meningitis spread?
By droplet infection
33
How is bacterial meningitis cured and prevented?
Curable with antibiotics if administered early enough, vaccines can protect against some forms
34
What are the mechanism and symptoms of bacterial meningitis?
Infection of the meninges (protective membranes on brain surface) which can spread to the rest of the body and cause fatal septicaemia. Symptoms vary depending on type of bacteria, but all share a blotchy red/purple non-blanching rash
35
Who are the main groups affected by bacterial meningitis?
Very young babies and 15-19 year olds
36
What is the mechanism of the HIV virus?
It attacks T helper cells, which gradually destroys the immune system and leaves sufferers vulnerable to secondary infection
37
What type of virus is HIV/AIDS?
A retrovirus
38
How does a retrovirus work?
A virus that is composed not of DNA but of RNA. Retroviruses have an enzyme, called reverse transcriptase, that gives them the unique property of transcribing their RNA into DNA after entering a cell. The retroviral DNA can then integrate into the chromosomal DNA of the host cell, to be expressed there.
39
What animals does bacterial meningitis affect?
Humans
40
What animals does HIV/AIDS affect?
Humans and some other primates
41
How is HIV spread?
Passed between people via infected bodily fluids i.e. via unprotected sex, shared needles, contaminated blood and mother to baby through either pregnancy or breastfeeding.
42
How is HIV cured?
No vaccine or cure but antiretroviral drugs can slow its progress
43
What animals does influenza affect?
Mammals and birds
44
What is the mechanism of influenza?
Infects ciliated epithelial cells in the gas exchange system, killing them and leaving the airways vulnerable to secondary infections such as bacterial pneumonia
45
Why is a vaccine made each year for flu?
Because flu viruses undergo small, regular mutations, so their surface antigens are constantly being reshuffled
46
Is the a cure for flu?
No
47
What causes malaria?
Several species of protoctista from the genus Plasmodium, with the most common being Plasmodium Falciparum, spread by the bite of the female Anopheles mosquito
48
What is the mechanism of malaria?
Infects red blood cells, liver, brain. Disease recurs, making people weak and vulnerable to secondary infection
49
What is the cure for malaria?
No vaccine and limited cures such as quinine, but preventative measures such as vector control through mosquito nets etc. can be very effective
50
What are 2 reasons malaria can be difficult to treat?
1. Protoctista 'hides' inside red blood cells 2. Caused by several different species so surface antigens may be different
51
What causes ringworm?
Fungi, with different fungi affecting different species.
52
What is a cure for ringworm or Athlete's Foot?
Antifungal creams
53
What are the symptoms of ringworm?
Grey-white, crusty, infectious circular area of skin which aren't damaging but are unsightly and itchy
54
What causes Athlete's Foot?
Tinia Pedia, a form of human ringworm fungus
55
Where does the Athlete's Foot fungus typically grow?
The warm, moist skin between toes, which it digests
56
What are the symptoms of Athlete's Foot?
Cracking and scaling which is itchy and may become sore
57
What animals does ringworm affect?
Mammals
58
What plants does Ring Rot affect?
Potatoes, tomatoes and aubergines
59
What is the cure for Ring Rot?
There is none
60
What happens to a field once it has been infected by Ring Rot?
It cannot be used to grow potatoes, tomatoes or aubergines for at least 2 years
61
What type of pathogen causes Ring Rot?
A bacterium
62
What does TMV infect?
Tobacco plants and 150 other species
63
How is TMV prevented and cured?
Resistant crop strains can prevent it but there is no cure
64
What is the mechanism of TMV?
Damages leaves, flowers and fruit, stunting growth and reducing yield, and can leads to almost total crop loss
65
What is Potato late blight caused by?
A fungus-like protoctista called an oomycete
66
How is Potato late blight prevented and cured?
No cure but can be prevented via use of resistant strains, careful management and chemical treatments
67
What is the mechanism of Potato late blight?
Hyphae penetrate host cells and destroy leaves, tubers and fruit, leading to millions of pounds of crop damage per year
68
What type of pathogen causes Black Sigatoka?
A fungus
69
What type of plant does Black Sigatoka affect?
Bananas
70
What part of the plant does Black Sigatoka affect?
The leaves
71
What is the mechanism of Black Sigatoka?
Hyphae penetrate and digest cells, turning leaves black. Can cause 50% reduction in yield of infected plants
72
How is Black Sigatoka cured and prevented?
No cure but resistant strains being developed and good husbandry and fungicide treatment can control the spread of the disease
73
What are the two main types of transmission of communicable diseases between animals?
Direct and indirect
74
What are the three main types of direct transmission in animals?
1. Inoculation 2. Direct contact 3. Ingestion
75
What happens in ingestion in the direct transmission of animal pathogens?
Contaminated food of drink are ingested or pathogens are transferred from the hands to the mouth
76
What are 3 ways pathogens can be spread via inoculation?
1. Animal bite i.e. rabies 2. Break in the skin i.e. unprotected sex 3. Puncture wound or shared needles i.e. septicaemia
77
What are 3 ways pathogens can be spread via direct contact?
1. Direct skin-to-skin contact i.e. ringworm, athlete's foot 2. Kissing or any contact with another person's bodily fluids i.e. many STDs or bacterial meningitis 3. Microorganisms from the faeces transmitted on the hands i.e. many diarrhoeal diseases
78
What are the 3 main types of indirect transmission of pathogens between animals?
1. Formites, eg towels 2. Vectors 3. Droplet infection
79
What occurs during a droplet infection?
Minute droplets of saliva or mucus are expelled from the mouth during talking, coughing or sneezing; if the droplets contain pathogens, anyone who inhales them may contract the illness
80
What are two types of disease which can be spread by droplet infection?
TB or influenza
81
What are the most common types of vector to spread diseases between animals?
Animals such as malaria-carrying mosquitoes, dogs, foxes and bats carrying rabies, fleas carrying the plague
82
What is a non-animal example of a vector (to spread diseases between animals)?
Water, which can transmit diarrhoeal diseases
83
What are some factors which can increase the risk of transmission of diseases between animals?
1. Poor nutrition 2. Overcrowded working and living conditions 3. A compromised immune system 4. Climate change, which can introduce new vectors and diseases to areas 5. In humans, poor disposal of waste provide a breeding grounds for vectors 6. Culture and infrastructure- in many countries, traditional practices can increase transmission 7. Socioeconomic factors such as a lack of trained health workers and insufficient public warning of outbreaks
84
Can plant pathogens be transmitted directly?
Yes, if a part of a healthy plant comes into direct contact with a part of an infected plant
85
What are some plant pathogens which can be transmitted directly?
Ring rot, TMV, black sigatoka, potato late blight
86
What are the two main types of indirect transmission of pathogens in plants?
1. Soil contamination 2. Vectors
87
How are plant pathogens transmitted via soil contamination?
Infected plants often leave pathogens or spores from fungi/protoctista in the soil, which can infect the next crop. Some pathogens or their spores can also survive the composting process, so the contaminated compost can infect plants it is spread on
88
What are the 4 main types of vectors which spread plant pathogens?
1. Wind 2. Water- spores swim in the film of surface water on leaves, and both spores and pathogens can be carried by raindrops 3. Animals- Insects and birds can carry pathogens and spores, and aphids can inoculate directly 4. Humans- Hands, clothing, fomites, farming practices and the transport of crops
89
What are some factors affecting the spread of communicable diseases between plants?
1. Planting varieties of crops which are susceptible to disease 2. Overcrowding increasing the likelihood of contact 3. Poor mineral nutrition reducing plants' resistance 4. Damp, warm conditions increasing the survival and spread of pathogens and spore 5. Climate change- increased rainfall and wind, new animal vectors, although drier conditions may reduce spread of disease
90
What are 3 things which act as physical barriers to pathogens in plants?
1. Waxy cuticle of leaves 2. Bark on trees 3. Cellulose cell wall
91
What is different about plants' and animals' responses to infection?
Animals attempt to heal damaged tissue, but plants just seal it off and sacrifice it
92
What are 3 cellular responses to infection in plants?
1. Producing defensive chemicals 2. Physically strengthening cell walls 3. Sending alarm signals to unaffected cells to trigger their defences
93
What 2 things can receptors in plant cells respond to upon infection?
1. Molecules from the pathogen 2. Chemicals produced when the plant cell wall is attacked by pathogenic enzymes
94
What two polysaccharides are made to strengthen plant cell walls upon infection?
Callose and lignin
95
What is the structure of callose?
Polysaccharide made up of beta glucose with 1-3 and 1-6 carbon linkages
96
What does callose do when a plant cell is infected?
1. Block sieve plates in the phloem, sealing off the infected part 2. Is deposited in the plasmodesmata between healthy cells and their neighbours 3. Within minutes of attack, synthesised and deposited between cell membrane and cell wall of cells neighbouring infected one. 4. More callose and lignin then added, strengthening the wall even further
97
What are some examples of plant chemical defences against pathogens?
1. Insect repellants 2. Anti-fungals 3. Insecticides 4. Antibacterial compounds (including antibiotics) 5. Anti-oomycetes 6. General toxins
98
What is an example of a general toxin made by plant cells as a chemical defence against pathogens?
Chemicals which can be broken down to make cyanide compounds
99
What are some examples of insect repellents made by plants?
Citronella from lemon grass or pine resin
100
What are some examples of insecticides made by plants?
Caffeine or pyrethrins, which are made by chrysanthemums and is an insect neurotoxin
101
What are some example of some antibacterial compounds made by plant cells?
1. Phenols 2. Gossypol 3. Defensins, plant proteins which disrupt bacterial and fungal cell membranes
102
What are phenols used for in plants?
As an antiseptic and antifungal agent
103
What are some examples of antifungal chemicals made by plants?
1. Phenols 2. Gossypol 3. Caffeine 4. Saponins- chemicals found in many plant cell membranes which interfere with fungal cell membranes 5. Chitinases- enzymes to break down chitin in fungal cell walls
104
What is caffeine toxic to?
Insects and fungi
105
What are the two mammalian lines of defence against pathogens?
1. Primary non-specific defences 2. Specific immune response
106
What is the outermost layer of the skin called?
The epidermis
107
What does the skin produce to inhibit pathogenic growth?
Oily sebum
108
What are the 3 ways skin serves as a defence against pathogens?
1. Oily sebum 2. Physical barrier 3. Skin flora of microorganisms
109
What are some examples of primary non-specific defences against disease in mammals which aim to keep pathogens out?
1. Skin 2. Mucous membranes 3. Digestive system 4. Tears 5. Urine 6. Expulsive reflexes 7. Blood clotting
110
What are some examples of primary non-specific defences against disease in mammals which work to get rid of pathogens?
1. Inflammation 2. Fever 3. Phagocytes
111
What are some examples of places that mucous membranes involved in the defence of the body against pathogens are found?
Airways, reproductive system, lungs, digestive system, gut, genitals, anus, ears and nose.
112
What are the two main types of cell which mucous membranes contain?
Goblet cells and ciliated epithelial cells
113
How do goblet cells help keep out pathogens?
They secrete sticky mucus, which traps pathogens and contains phagocytes and also lysosomes, which contain enzymes called lysozymes which can kill bacteria and fungi by destroying their cell walls
114
How do ciliated epithelial cells help keep out pathogens?
They waft mucus containing pathogens to places where it can be destroyed or expelled; for example, in the airways they waft it to the top of the trachea, where it can move into the oesophagus for expulsion
115
How does stomach acid act as a barrier to pathogens?
It is very acidic at pH 1-2, so can denature pathogens' enzymes
116
How do tears and urine act as a barrier to pathogens?
They both contain lysosomes, and tears have ions to lower their water potential and potentially crenate pathogens
117
What are 4 examples of expulsive reflexes and what do they all do?
Coughing, sneezing, vomiting and diarrhoea all eject pathogen-laden fluids from the body
118
What do platelets attach to in a blood clot?
The skin or damaged cells which release substances that attract platelets
119
What happens in wound repair after a blood clot has formed?
1. Cut dries to form a scab 2. Epidermal cells below scab reproduce to seal off wound permanently 3. Damaged blood vessels regrow 4. Collagen fibres deposited to give new tissue strength 5. Once new epidermis reaches normal thickness, scab sloughs off
120
What chemicals cause a fever?
Cytokines, which stimulate the hypothalamus to 'reset' the body thermometer to a higher temperature
121
How does fever work to get rid of pathogens?
Pathogens can't reproduce as well at a higher temperature and the specific immune response works faster at a higher temperature
122
What is inflammation characterised by?
Redness, swelling, pain, heat and possibly a full body rash if the infection is widespread
123
What two chemicals are released by activated mast cells in damaged tissue?
Histamines and cytokines
124
What do cytokines do in inflammation?
Attract white blood cells to the site of the wound to dispose of pathogens by phagocytosis
125
What is oedema?
Swelling caused by a large accumulation of tissue fluid
126
What do histamines do in inflammation?
Cause smooth muscle in the walls of blood vessels to relax, which: 1. Causes the blood vessel to dilate, raising local temperature to disadvantage pathogens and causing heat and redness 2. Makes the blood vessel walls more leaky, causing oedema and pain
127
What are the two main types of phagocyte?
Neutrophils and Macrophages
128
Where are neutrophils and macrophages made?
Bone marrow
129
What type of nucleus does a neutrophil have?
Multi-lobed
130
Where are neutrophils found?
Blood, tissue fluid and epithelial surfaces
131
Are neutrophils long or short-lived?
Short-lived
132
What is pus made up of?
Dead phagocytes and pathogens
133
Are macrophages smaller or larger than neutrophils?
Larger
134
What do macrophages travel in the blood as?
Monocytes
135
Where do macrophages develop and settle?
The lymph nodes
136
How long does is usually take a human neutrophil to engulf and destroy a bacterium?
Under 10 minutes
137
What is a phagosome-lysosome complex called?
Phagolysosome
138
Why do macrophages take longer than neutrophils to digest a pathogen?
They produce a MHC from a pathogenic antigen and become an antigen-presenting cell
139
What is an APC?
An antigen-presenting cell, which is a macrophage with at least one MHC
140
What are the stages of phagocytosis?
1. Phagocyte attracted to pathogen by chemicals the pathogen produces 2. Phagocytes recognise non-human proteins on the pathogen, and a glycoprotein on the cell-surface membrane of the phagocyte binds to a pathogenic antigen 3. Pathogen is engulfed into a vesicle called a phagosome 4. Phagosome combines with lysosome to form phagolysosome, with enzymes destroying the pathogen 5. If the cell is a macrophage, pathogenic antigens can be combined with proteins to form an MHC, which is presented on the cell surface to stimulate other immune cells
141
What chemicals do phagocytes containing a pathogen produce?
Cytokines
142
What do opsonins do?
They 'tag' pathogens to make them more easily recognisable by phagocytes, which have opsonin-binding sites on their cell surface membrane
143
What are two examples of opsonins?
Immunoglobulin G and Immunoglobulin M
144
What type of biological molecule is an antibody?
Polypeptide/protein
145
What are 3 places a T or B lymphocyte can come across an antigen?
1. A pathogen in bodily fluids 2. MHC on a macrophage 3. Infected cell
146
Where are T lymphocytes activated?
Thymus
147
Where are B and T lymphocytes produced?
Bone marrow
148
How long does the specific immune response take to respond to a new pathogen?
Up to 14 days
149
What are the two chain types in an antibody?
Heavy chain and Light chain
150
What is the part of an antibody which is the same across all antibodies called?
Constant region
151
What is the part of an antibody which changes from antibody to antibody called?
Variable region
152
What are the polypeptide chains in an antibody joined by?
Disulfide bridges
153
How many polypeptide chains make up an antibody?
4 (2 heavy, 2 light)
154
Which parts of an antibody form antigen-binding sites?
The variable regions
155
What is the purpose of the hinge region of an antibody?
Allows flexibility when the antibody binds to the antigen
156
What is the purpose of the constant region of an antibody?
Allows binding to receptors on immune system cells such as phagocytes
157
What are the 3 ways antibodies can help clear an infection?
1. Agglutinating Pathogens 2. Neutralising toxins 3. Preventing the pathogen binding to human cells
158
How many antigens can an antibody bind to at once?
2
159
Why are antigen-antibody complexes easily engulfed and digested by phagocytes?
The antibodies act as opsonins
160
How do antibodies neutralise toxins?
They are bound to any other antigen, and the antibody-toxin complex is phagocytosed
161
How does the agglutination of pathogens by antibodies help clear the body of infection?
Because antibodies have two binding sites, they can bind to antigens on two different pathogens at once, causing them to clump together and allowing lots of pathogens to be phagocytosed at once
162
What are antibodies which agglutinate pathogens called?
Agglutinins
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How do antibodies prevent pathogens binding to human cells?
When binding to antigens on the pathogen, they can block the cell surface receptors which pathogens require to bind to host cells, so the cells cannot be attached to or infected
164
Where do B lymphocytes mature?
The bone marrow
165
What are the 4 main types of T lymphocytes?
1. T regulator 2. T helper 3. T killer 4. T memory
166
Which 2 harmful chemicals do T killer cells use?
Hydrogen peroxide and perforin
167
How does perforin kill pathogens?
It makes holes in their cell surface membrane so that it is freely permeable
168
What do T lymphocytes respond to in cell-mediated immunity?
A cell of the organism which has been changed in some way, such as a cell infected virally, one presenting antigens or one which has undergone a random genetic mutation, or cells from transplanted tissue
169
What is the purpose of a T killer cell?
Kill pathogens using harmful chemicals
170
What are the 3 types of B lymphocyte?
1. Plasma cell 2. B effector cell 3. B memory cell
171
What is the purpose of a B effector cell?
Differentiate into the required plasma cell
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What is the purpose of a plasma cell?
Produce antibodies specific to the pathogen
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How many antibodies can a plasma cell produce when active?
~2000 antibodies per second
174
What is the lifespan of a plasma cell?
A few days
175
What is the purpose of a B memory cell?
Live a very long time an remember a particular antigen so that the body can mount a quick response to it if necessary
176
What is the purpose of a T memory cell?
Live a very long time and remember a pathogen, then produce lots of T killer cell clones if it is ever encountered again
177
What chemicals are important in the function of T regulator cell?
Interleukins
178
What is the purpose of a T regulator cell?
Stop the immune system once an infection is over, prevent the body setting up an autoimmune response and ensuring that it recognises self antigens
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What are interleukins a type of?
Cytokine
180
What do T helper cells produce?
Interleukins
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What do the interleukins produced by T helper cells do?
Stimulate the activity of B cells, which in turn stimulates the production of antibodies, stimulates production of other types of T cell by mitosis, and attracts and stimulates macrophages to ingest pathogens with antibody-antigen complexes
182
What is cell mediated immunity especially important against?
Viruses and early cancers
183
What type of cell can T helper cells differentiate into?
T memory cells
184
How long does it take for antibodies to start to be produced after an infection?
Around 5 days
185
What happens in clonal selection?
The undifferentiated T or B lymphocyte has a receptor complementary to the pathogen's antigen (either in an MHC in cell mediated immunity or on a pathogen in humoral immunity). It binds to the antigen using this, and the lymphocyte then divides rapidly by mitosis
186
What does the body respond to in humoral immunity?
Antigens found outside of cells (for example on pathogens) or on APCs
187
What is clonal expansion?
Where a B cell activated by interleukins divide to give clones of plasma cells and B memory cells
188
What is the primary immune response?
The response to a previously unseen pathogen, where it can take days or weeks for the correct antibody to be produced
189
What is the secondary immune response?
Where B and T memory cells respond rapidly to a known pathogen and quickly deal with the infection
190
What type of antibodies does humoral immunity produce?
Ones which are soluble in blood and tissue fluid, and not attached to cells
191
What are 3 examples of autoimmune diseases?
1. Lupus 2. Type 1 diabetes 3. Rheumatoid arthritis
192
What part of the body does Type 1 diabetes affect?
Insulin-secreting cells of the pancreas
193
Are Lupus or Rheumatoid arthritis curable?
No, you can only manage their symptoms
194
What parts of the body are affected by Rheumatoid arthritis?
The joints, especially those in the hands, wrists, ankles and feet
195
What are some symptoms of Rheumatoid arthritis?
Tender, swollen, warm joints, joint stiffness, fatigue, fever, weight loss
196
What are some treatment options for Rheumatoid arthritis?
Steroids, pain relief, immunosuppressants, anti-inflammatory drugs
197
What parts of the body are affected by lupus?
Often the skin and joints but can affect any organ in the body including the kidneys, liver, lungs and brain
198
What are some symptoms of Lupus?
Fatigue, aching joints, skin rash, fever, hair loss, seizures, sores on the mouth and/or nose
199
What are some treatment options for Lupus?
Steroids, anti-inflammatories, immunosuppressants, various other such as transplant of the infected organ
200
What is an autoimmune disease?
One in which the immune system stops recognising its own cells and starts attacking healthy tissue
201
What is a disadvantage of using immunosuppressant drugs to treat autoimmune disease?
This deprives the body of its natural defence against communicable disease
202
What causes autoimmune disease?
It is not fully understood by science but there is a genetic tendency in some families, sometimes T regulator cells don't work properly and sometimes the body reacts badly to a normally mild pathogen
203
What are the 4 main types of immunity?
1. Natural 2. Artificial 3. Passive 4. Active
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What is active immunity?
Immunity provided by activation of the immune system
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What are 5 examples of different antigenic material used in vaccines and diseases each would be used for?
1. Whole, live microorganisms (smallpox) 2. A dead pathogen (cholera and typhoid) 3. A harmless or attenuated (reduced virulence) virus (Measles) 4. A preparation of antigens (Hepatitis B) 5. Some harmless toxin (tetanus)
206
What is passive immunity?
Provided by antibodies which have not been manufactured by stimulating the recipient's immune system
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What is natural immunity?
Achieved as the result of the entry of a pathogen and its antigenic material, which stimulates an immune response
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What is artificial immunity?
Gained by deliberate exposure to antibodies or antigens
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Give an example of natural passive immunity
Antibodies provided via the placenta or breast milk
210
Give an example of artificial passive immunity
Immunity provided by injection of antibodies made by another individual
211
Give an example of natural active immunity
Immunity provided by antibodies made in the immune system as a result of infection
212
Give an example of artificial active immunity
Immunity provided by antibodies made in the immune system as a result of a vaccine
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How old do you have to be before your body starts making antibiodies?
At least a couple of months old
214
What is colostrum and why is it special?
The first milk a mammalian mother makes, special because it is very high in antibodies
215
What is notable about the type of antibodies in colostrum?
They are likely to be relevant to pathogens found in the environment, where the mother encountered them
216
How long does natural passive immunity last? (Specifically in new borns)
Until the baby begins making its own antibodies
217
Where are the tetanus antibodies used in vaccines extracted from?
The blood of horses
218
How does vaccination work?
1. Small amounts of safe antigen (the vaccine) are injected into the blood 2. The body's primary immune response is triggered and it works as if the antigens were a real pathogen 3. If the pathogen ever does enter the body, memory cells left over from the first injection will cause the secondary immune response to rapidly kill all pathogens and prevent symptoms of an infection
219
What is an epidemic?
When a communicable disease spreads rapidly to a lot of people on a local or national level
220
What is a pandemic?
When a communicable disease spreads rapidly to a lot of people on an international or intercontinental level
221
What is herd immunity?
Using a vaccine to provide immunity to all or almost all of a population at risk- once enough people are vaccinated (which varies depending on the disease), the disease can no longer spread
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What are two examples of prevalent diseases which we so far do not have a vaccine for?
Malaria and HIV/AIDS
223
Why is Malaria so hard to make a vaccine for?
The plasmodium parasite spends a lot of time in erythrocytes so is protected from the immune system by self antigens, and once in the body the surface antigens of the parasite can reshuffle
224
Why is HIV/AIDS so hard to make a vaccine for?
It enters the macrophages and T helper cells, so disables the immune system itself
225
What are some examples of medicines which treat symptoms?
Anti-acid drugs for indigestion, anti-inflammatories, painkillers
226
What are some examples of medicines which cure diseases?
Chemotherapy drugs for some cancers, antibiotics, antifungals
227
What was the first widely used antibiotic and where is it derived from?
Penicillin, derived from a fungal mould
228
When was Penicillin first discovered and by whom?
1928 by Alexander Fleming
229
What do bactericidal antibiotics do?
Kill bacteria, either by interfering with the cell wall or with the cell contents
230
What do bacteriostatic antibiotics do?
Stop bacteria from multiplying by interfering with either bacterial protein production or DNA replication
231
What drug can be extracted from the bark of a willow tree and what is it used for?
Aspirin (in which the active ingredient is salicylic acid), used as a painkiller, anti-inflammatory, anti-coagulant and anti-pyretic (to reduce fever)
232
What is a negative effect of loss of biodiversity on medicine?
Many medicines are naturally derived, so we may be losing out on undiscovered medicines if undiscovered species are wiped out
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What are some modern methods of discovering new medicines?
Using computers to build 3D models of pathogens, antigens and drugs for analysis, using computers to search through huge libraries of chemicals for useful ones, analysis of pathogenic or cancerous cell genomes
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What are some ways in which medicine will likely change in the future?
Increase in personalised medicine based on pharmacogenetics, use of synthetic biology to develop and produce new drugs, use of nanotechnology to deliver drugs more precisely
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What does synthetic biology enable us to do?
Genetically engineer bacteria or even mammals to produce medicines cheaply, quickly and efficiently
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What are two notable examples of antibiotic-resistant bacteria?
MRSA and C.Difficile
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What is MRSA?
Methicillin Resistant Staphylococcus Aureus, a bacterium carried by up to 30% of the population on the skin or in the nose, which causes boils, abscesses and potentially fatal septicaemia, and which is resistant to methicillin
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What is C.difficile?
Clostridium difficile, a bacterium in the guts of around 5% of the population which produces toxins that damage the lining of the intestines, leading to diarrhoea, bleeding and sometimes death.
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When does C.difficile become a problem for someone?
When commonly used antibiotics kill off gut bacteria but it survives due to resistance, allowing it to reproduce and take hold rapidly
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What are some long-term methods of reducing the number of antibiotic-resistant bacteria?
1. Minimising the use of antibiotics 2. Making sure that courses of antibiotics are completed 3. Good hygiene in hospitals, care homes and in general
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What are some ways in which the problem of antibiotic resistance is being combated?
New antibiotics are being searched for and developed, adding antibiotics to animal feed to prevent infection banned in the UK
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How do cytokine molecules stimulate specific groups of B lymphocytes?
Cytokines have specific shape complementary to the receptor on the cell surface membrane B lymphocyte. This stimulates clonal expansion.
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Define Parasite
Lives in host. Lives off host digesting cell organelles gaining nutrition from this at the expense of the host.
