communicable diseases Flashcards
1
Q
name for an organism which causes disease?
A
pathogen
2
Q
name for organism on which a pathogen lives and the effects of a pathogen
A
host; takes nutrition and causes damage
3
Q
Describe behaviour of bacteria (2)
A
Produce threads called hyphae which form system called mycelium, can penetrate, often live in vascular tissues of plants, release enzymes which digest surrounding substances
4
Q
How do viruses replicate and spread?
A
Invade cells and take over genetic machinery to copy itself, host cell bursts releasing more of the virus
5
Q
Describe protocista and their behaviour
A
animal-like organisms, cause harm by entering and feeding on host cells as they grow
6
Q
Name two bacterial animal diseases
A
Tuberculosis and bacterial meningitis
7
Q
Name one bacterial plant disease
A
ring rot
8
Q
Name three animal viral diseases
A
HIV/AIDS, measles and influenza
9
Q
Name one viral plant disease
A
Tobacco mosaic virus
10
Q
Name two fungal plant diseases
A
Black sigatoka in bananas and rose black spot
11
Q
Name two fungal animal diseases
A
Ringworm in cattle and athlete’s foot in humans
12
Q
Name one protocistan animal disease
A
Malaria
13
Q
Name one protocistan plant disease
A
Blight in tomatoes and potatoes
14
Q
State the four stages of the life cycle of a pathogen
A
Travel to new host; enter tissues; reproduce; leave tissues
15
Q
Name four types of direct transmission
A
Direct physical contact; faecal-oral; droplet infection; spores
16
Q
What is direct transmission by physical contact?
A
transmission of a disease by touching contaminated individual or surfaces
17
Q
What is direct faecal-oral transmission?
A
eating contaminated food/water
18
Q
What is direct droplet transmission?
A
infection from air-borne droplets/contaminants
19
Q
What is direct transmission by spores?
A
spores travelling in air/residing on soil cause infection
20
Q
How to avoid transmission by contact?
A
Wash hands regularly;
keep surfaces clean;
clean and disinfect wounds and equipment;
condoms during intercourse
21
Q
How to avoid faecal-oral transmission?
A
cleanse of waste water and drinking water, in some parts of world human waste water used fertilise crops;
wash and prepare fresh food for cooking
22
Q
How to avoid droplet transmission?
A
Cover mouth when coughing or sneezing and bin tissues
23
Q
How to avoid transmission by spores? (2)
A
Wear a mask;
wash skin after contact with soil
24
Q
Name six social factors which affect transmission
A
overcrowding, e.g. in houses;
poor ventilation;
poor health;
poor diet;
homelessness;
living around those migrated from areas where disease more common
25
Example of poor health increasing risk of transmission
someone with HIV are more likely to be infected with other diseases due to their weakened immune system
26
How are pathogens transmitted indirectly?
via a vector, another organism used by pathogen to gain entry to host
27
Name parasite which causes malaria
Plasmodium
28
Name the vector which carries plasmodium
female anopheles mosquito
29
Example of vector transmission in animals
The plasmodium parasite which causes malaria enters human via bite from female anopheles mosquito
30
Three ways plant diseases are transmitted directly
Pathogens enter roots if damaged;
airborne transmission of spores;
infection of vascular tissue
31
How does infection of vascular tissue cause direct transmission?
vascular tissue in leaves infected, leaves drop off and infect the soil and other plants, or seeds are redistributed and infect offspring
32
Explain indirect vector transmission in plants
insect attacks and pathogen attaches to insect (vector), transmitted to next attacked plant
33
How does climate affect disease?
pathogens grow rapidly in warm and moist conditions, in cold they may be damaged or killed and cant reproduce, infection more common in warm climate
34
Why plants attractive to pathogens and vectors?
Create sugars in photosynthesis, used for proteins and oils, nutrients for organisms to thrive.
35
Describe passive defences
Present before infection, prevent entry and spread of all kinds of pathogen
36
Name seven physical passive defences of plants
Cellulose cell wall;
lignin thickening of cell walls;
waxy cuticle;
bark;
stomatal closure;
callose;
tylose formation
37
How does the cell wall protect plants?
physical barrier with active chemical defenses
38
How does lignin thickening protect plants?
lignin waterproof and indigestible, barrier
39
How does the waxy cuticle protect plants?
prevents water collecting on leaves, which is needed by pathogens to survive
40
How does bark protect plants?
contains various chemical defences like tannins which work against organisms
41
How does stomatal closure protect plants?
when pathogens detected guard cells close in that part of plant
42
How does callose protect plants?
Large polysaccharide deposited in sieve tubes, blocks flow through sieve plates, prevent pathogen spread around plant
43
How does tylose formation protect plants?
Swelling which fills xylem vessel, stops flow of water preventing spread through plant, contains anti-pathogenic toxins
44
Why are chemicals not always present in plants?
production of chemicals requires energy, many only produced when infection detected
45
Two areas chemicals always present in plants
Bark and tylose formation
46
Reaction when pathogens are detected by a plant
detected by chemicals in cell walls, plant fortify present defences, increasing physical defences and producing chemicals.
47
Five active defences of plants
Cell walls thickened and strengthened with extra cellulose;
deposition of callose;
oxidative bursts;
increase in production of chemicals;
necrosis;
48
Five defensive chemicals in plants
Terpenoids; Phenols; Alkaloids; Defensive proteins (defensins); hydrolytic enzymes
49
How does callose act as an active defense in plants?
Deposited between cell wall and membranes of area near invading pathogen to prevent cellular penetration, strengthen cell wall and block plasmodesmata
50
What is necrosis?
deliberate death of cells around invading pathogen
51
How does necrosis defend against pathogens?
limit pathogens access to nutrients and water and stops spread around plant
52
How is necrosis initiated?
By intracellular enzyme triggered by damage caused by pathogen
53
How oxidative bursts act as active defense in plants?
Releases reactive oxygen, which can damage invading pathogen
54
What are terpenoids?
essential oils with antibacterial and antifungal properties
55
Give example of terpenoids
menthols produced by mint plants
56
What is a canker?
Necrotic lesion in woody tissue like main stem or branch. Causes death of cambium tissue in bark
57
What are phenols?
Chemicals with antibiotic and antifungal properties
58
Give example of phenol
tannins in bark
59
How do tannins work?
Bind to and deactivate digestive enzymes like trypsin and chymotrypsin;
Stops growth of insect, then dies
60
What are alkaloids?
Nitrogen-containing compounds with bitter taste
61
Five examples of alkaloids
caffeine, nicotine, cocaine, morphine, solanine
62
What does a blood clot consist of?
Platelets, fibrin, rbcs
63
Describe role of mucus membranes
Line airways and protect vulnerable exchange areas from infection, trapping pathogens
64
How is mucous formed in the airways?
secreted by goblet cells in the epithelial layer
65
How do mucus membranes protect the body from infection? (4)
lines airways and traps pathogens;
cilia waft mucous in coordination to the throat;
mucus can enter oesophagus;
swallowed and often killed by acids in stomach
66
How do alkaloids protect plants? (3)
Bitter taste stops herbivores feeding;
inhibit/activate various metabolic reactions like protein synthesis in herbivore;
preventing damage by animals prevents entrance of pathogens
67
What causes coughing and sneezing?
irritation caused by pathogens, reflexes intended to expel the pathogens
68
How does inflammation occur? (4)
microorganisms detected by mast cells;
release cell signaller histamine;
causes vasodilation;
wbcs and plasma leave, increased tissue fluid, swelling in infected area
69
How can inflammation trigger the specific immune response?
excess tissue fluid drains into the lymphatic system, lymphocytes in lymph may be activated triggering APCs and the immune response
70
What is vasodilation?
widening of blood vessels, capillaries become more permeable, wbcs can leave causing inflammation during an infection
71
How is histamine released?
by mast cells, which detect infection by a microorganism
72
How do defensins protect plants?
inhibit action of ion transport channels in plasma membrane of pathogens
73
What are the two stages of secondary active defence?
phagocytic defence - non specific
the immune response - specific
74
What are phagocytes
wbcs which engulf and digest pathogens
75
Three types of hydrolytic enzyme in plants
chitinases, glucanases, lysosomes
76
Name two types of phagocyte
neutrophil and macrophage
77
What are neutrophils and how do they defend against pathogens?
Most common phagocyte, squeeze out into tissue fluid during infection and engulfs pathogens, die quickly and act fast
78
Where are neutrophils made and how do they travel?
made in bone marrow, travel in the blood
79
What do chitinases do?
Break down chitin in fungal cell walls of invading organism
80
Describe the process of phagocytosis (4)
phagocyte binds to opsonin attached to antigen of pathogen;
pathogen engulfed by endocytosis, forms phagosome;
lysosomes fuse with phagosome (phagolysosome) releasing enzymes;
pathogens digested and products absorbed
81
What is a lysosome?
vesicle containing powerful hydrolytic enzymes
82
What do macrophages do?
engulfs pathogens but doesn't digest antigens, displays them on surface, travels in lymphatic system, activating lymphocytes and triggering specific immune response
83
Which cells act as APCs?
macrophages and infected body cells
84
Distinct characteristic of macrophages
larger, kidney shaped nucleus
85
Where are macrophages made and how do they travel?
bone marrow, travel in the blood as inactive monocytes, are activate at lymph nodes
86
Why do cells not attack macrophage APCs?
Antigens presented by special protein complexes which show they are not a pathogen
87
Body cell which displays foreign antigens?
Antigen-presenting cell (APC)
88
How do APCs trigger immune response?
Move around body to activate specific T and B lymphocytes with complimentary receptors, increases chance/speed of finding specific lymphocytes
89
Name for activation of T and B lymphocytes?
Clonal selection
90
What is clonal selection?
activation of specific T and B lymphocytes
91
What are cytokines?
chemical signalling molecules
92
Cell types T-lymphocytes differentiate into (4)
T helper (Th)
T killer (Tk)
T memory (Tm)
T regulator (Tr)
93
Role of T-helper cells
release interleukins, stimulate proliferation of B cells and phagocytosis
94
Role of T-killer cells
Attack and kill body cells containing the pathogen using perforin
95
Role of T and B memory cells
Remain in blood and provide long term immunity, trigger rapid release of antibodies
96
Role of T-regulator cells
End immune response when pathogen killed , prevents development of auto-immune diseases
97
Cells B lymphocytes differentiate into?
Plasma
B memory (Bm)
98
Role of plasma cells
travel body releasing antibodies for a specific antigen
99
How do cells communicate?
release of cytokines, chemical signallers, target cell has receptors complimentary to signalling molecule
100
Three examples of cytokines
- monokines
- interleukins
- interferons
101
What is an autoimmune disease?
Immune system attacks healthy body cells
102
How body prevents autoimmune diseases?
T and B cells with receptors complimentary to body cells are destroyed during early development
103
What is proliferation?
Clonal expansion, T and B cells increase in numbers by mitosis
104
Two examples of autoimmune diseases?
arthritis and lupus
105
Describe arthritis
painful inflammation of joint, antibodies attack membranes of surrounding cells
106
Describe lupus
affects any part of body, causes swelling and pain, sometimes antibodies attack proteins in the nucleus of affected cells
107
What is the specific immune response?
Specific lymphocyte action where antibodies and memory cells are created
108
What do interleukins do?
stimulate clonal expansion/proliferation and differentiation of T and B cells
109
What type of protein are antibodies?
immunoglobulins
110
How do antibodies bind to pathogens?
they are complementary to the specific shape of the pathogen
111
Describe the structure of an antibody (6)
Y shaped;
made four polypeptide chains, 2 heavy and 2 light;
held by disulphide links;
variable region where attaches to antigens, differs between antibodies;
constant region always the same;
hinge region for flexibility
112
How are polypeptide chains in an antibody held together?
by disulfide bridges
113
Name the two regions of an antibody
variable and constant
114
Name three main groups of antibodies
opsonins;
agglutinins;
anti-toxins
115
Describe the role of opsonins
binding site for phagocytic cells so they can engulf pathogen;
prevents antigens from binding to and entering host cell
116
Describe the role of agglutinins
act like glue - each bind to two pathogens, cause pathogens to be clumped (agglutinated) together;
cannot enter host cells and are readily engulfed by pathogens
117
What are agglutinated pathogens?
pathogens clumped together by the binding of agglutinins (antibodies)
118
Describe the role of antitoxins
attach to molecules released by pathogens, rendering them harmless
119
Describe the primary immune response graph
when first infected, antigens must be recognised and antibodies made. slow process, few days before infection can be handled. after destroyed, antibody concentration drops rapidly
120
Describe the secondary immune response
B and T memory cells in blood recognise a second infection and start quicker immune response, rapid creation of antibodies and much higher concentration, often prevents symptoms being felt in host
121
How does a vaccination work?
Host exposed antigenic material, and immune system treats it as the real disease;
memory cells are made which makes host immune
122
Five forms of antigenic material used in vaccines
live microorganisms with similar antigens;
weakened pathogen;
dead pathogen;
preparation of antigens;
a toxoid, harmless toxin
123
Describe the herd vaccination method
Protecting the whole population, by immunising majority of population, disease cannot spread, causing herd immunity (
124
Describe ring vaccination method
Immunising people in immediate area of outbreak to stop spread
125
When is ring vaccination commonly used?
to stop the spread of livestock disease, as they are held within one area
126
How can pathogens overcome vaccination?
Pathogens may undergo mutations which change their antigens and render vaccination useless, as antibodies can no longer bind
127
How might an epidemic begin?
when antigens of a pathogen change and overcome existing treatment
128
Describe an active and passive form of natural immunity
active - immunity from previous infection and immune response
passive - antibodies provided to baby from placenta and breast milk while immune system still developing
129
What is an epidemic?
a widespread occurrence of an infectious disease in a community at a particular time.
130
What is a pandemic?
worldwide epidemic
131
What is an epidemic?
a widespread occurrence of an infectious disease in a community at a particular time.
132
What is active immunity?
Immunity caused by immune system response and attack, creating antibodies and memory cells
133
What is passive immunity?
Immunity usually temporary caused by external supply of antibodies, does not involve creation of antibodies by the immune system
134
Describe an active and passive form of artificial immunity
active - immunity by immune response to injected antigens (vaccine)
passive - immunity from antibodies injected by another individual
135
Who is most at risk of influenza virus?
people with respiratory tract conditions
136
Three reasons new medicines are needed
New diseases emerging;
existing diseases with no treatment;
antibiotics becoming less effective
137
Eight ways new medicines may be discovered/developed
accidental discovery;
traditional remedies;
observation of wildlife;
further plant research;
research into disease causing mechanisms;
personalised medicines;
synthetic biology;
antibiotic use and abuse
138
How is plant research useful for developing medicines? (2)
can locate active ingredient in plant which gives medicinal properties;
lots of potential - tropical plants still have wide range and diversity
139
How does studying microorganisms help develop medicines?
can attempt to find a way to block their attack e.g. drugs to inhibit pathogen from binding to body cells
140
What are defensins?
Small anti-microbial cysteine-rich proteins
141
Where are hydrolytic enzymes found in plants?
Found in spaces between cells
142
State 8 primary defences of the body (8)
Skin;
skin repair/blood clotting;
mucous membranes;
coughing and sneezing;
inflammation;
enzymes in tears;
earwax;
female cervical mucus plug
143
How does skin protect the body? (2)
Physical barrier;
cells die and eventually are shed along with any pathogens
144
Describe the structure of the skin
Outer layer epidermis, made up of layers. Most of cells called keratinocytes.
145
How has misuse of antibiotics caused issues?
Overuse and misuse of antibiotics has caused pathogens to develop a resistance to them, so are less-effective in present day;
e.g. C. diff and MRSA
146
Two examples of antibiotic resistant bacteria
MRSA and C. diff
147
How does perforin kill infected cells?
breaks down the cell membrane
148
Three examples of vectors which transmit disease?
wind, water, insects
