chapter 12 - communicable diseases Flashcards
(119 cards)
1
Q
health
A
a state of complete physical, mental and social well-being and not merely the absence of disease or infirmiry
2
Q
communicable disease
A
a disease which can be spread between organisms
3
Q
pathogen
A
microorganisms that cause disease; live on/in a host and can take nutrition from them
4
Q
epidemiology
A
the study of the spread of diease and the factors affecting it
5
Q
pandemic
A
a worldwide epidemic
6
Q
mortality
A
the number of people who die each year from a disease
7
Q
prevalence
A
the number of people with a disease at a given time
8
Q
endemic
A
a disease that is always present in the population
9
Q
epidemic
A
a disease that spreads rapidly to a lot of people over a wide area
10
Q
morbidity
A
departure from health
11
Q
examples of bacteria caused diseases
A
tuberculosis and ring rot
12
Q
effects of toxins produced by bacteria
A
- break down plasma membrane
- damage enzymes
- prevent mitosis
13
Q
features of viruses
A
- non-living pathogens
- 50x smaller than bacteria
- genetic material surrounded by a protein coat
- evolve rapidly
14
Q
how do viruses cause damage?
A
- invade living cells and take over the host cell’s genetic machinery
- they cause the cell to manufacture more copies of the virus and the cell eventually lyses releasing new viruses
15
Q
what are viruses that infect bacteria called?
A
bacteriophages
16
Q
features of protoctista
A
- eukaryotes
- can be found as single-celled organisms and colonies of cells
- some need a vector to transfer to hosts
17
Q
features of fungi
A
- eukaryotic
- often multicellular
- many are saprophytes
18
Q
saprophytes
A
organisms that secrete enzymes onto dead/decaying matter to digest it
19
Q
effect of fungi on plants
A
- when leaves are affected, photosynthesis stops
- fungi reproduce producing millions of spores which can cause the fungus to spread rapidly and widely through crop plants
20
Q
which pathogen causes black sigatoka?
A
fungus
21
Q
what is the mode of transport for black sigatoka?
A
spores spreading in wind and rain
22
Q
what organisms are affected by black sigatoka?
A
bananas
23
Q
what pathogens cause ring rot?
A
bacterium
24
Q
what is the mode of transport for ring rot?
A
direct contact or contaminated water, soil, tools
25
what organisms are affected by ring rot?
potatoes
26
what pathogen causes HIV/AIDS?
virus
27
what is the mode of transport for HIV?
mixing bodily fluids
28
what organisms are affected by HIV/AIDS?
humans
29
what pathogen causes tobacco mosaic virus?
virus
30
what is the mode of transport for tobacco mosaic virus?
direct contact or contaminated tools
31
what organisms are affected by tobacco mosaic virus?
tobacco plants, tomatoes
32
what pathogen causes potato/tomato late blight?
protoctist
33
what is the mode of transport for potato/tomato late blight?
spores, direct contact and aphid vectors
34
what pathogen causes tuberculosis?
bacterium
35
what is the mode of transport for tuberculosis?
droplet infection
36
what organisms are affected by tuberculosis?
humans, cows
37
what pathogen causes malaria?
protoctist
38
what is the mode of transport for malaria?
vector - mosquitoes
39
what organisms are affected by malaria?
humans
40
what pathogen causes athlete's foot?
fungus
41
what is the mode of transport for athlete's foot?
direct contact and towels or damp floors
42
what organisms are affected by athlete's foot?
humans
43
what pathogen causes influenza?
virus
44
what is the mode of transport for influenza?
droplet infection, hands and surfaces
45
what organisms are affected by influenza?
humans, pigs, birds
46
direct methods of transport of pathogens between animals
direct contact, ingestion, inoculation
47
indirect transmission of pathogens between animals
droplet infection, formites (inanimate objects), vectors
48
factors affecting transmission of pathogens in animals
overcrowded living and working conditions
poor nutrition
compromised immune system
poor disposal of waste
climate change
49
methods of pathogen transmission between plants
direct contact, soil contamination, wind, water, vectors (animals and humans)
50
factors affecting pathogen transmission between plants
planting varieties of crops that are susceptible
overcrowding
poor mineral nutrition
damp, warm conditons
climate change
51
how does a cellulose cell wall act as a defence against pathogens?
physical barrier
52
how does lignin act as a defence against pathogens?
thickens the cell wall, is waterproof and almost completely indigestible
53
how does bark act as a defence against pathogens?
prevents water collecting on cell surface in which pathogens could survive
54
how does stomatal closure act as a defence against pathogens?
prevents entry of pathogens
55
how does tylose act as a defence against pathogens?
tylose are outgrowths of xylem parenchyma in lumens of xylem vessels via pits, they prevent passage of water and spread of pathogens
56
how does callose act as a defence against pathogens?
is a polysaccharide that blocks sieve tubes acting as a barrier to limit the spread of pathogens
57
chemical defences in plants against pathogens
toxins, insect repellents, insecticides, antibacterial and antifungal
58
how does the skin act as a defence againt pathogens?
acts as a physical barrier to pathogens
contains healthy microbes to compete with pathogens
produces sebum that inhibits growth of pathogens
59
how do mucous membranes act as a defence against pathogens?
protects body opening
goblet cells in epithelium secrete mucus to trap pathogens
ciliated epithelium wafts mucus upwards to be swallowed and killed by stomach acid
60
how do expulsive reflexes act as a defence againt pathogens?
reflex responses which attempt to expel foreign objects from the body eg coughs, sneezes, vomiting
61
what does thrombin convert fibrinogen to?
fibrin
62
how do blood clots act as a defence against pathogens?
seal wounds to prevent entry of pathogens
63
how does wound repair work?
serotonin is released which causes the walls of the blood vessels to contract
the clot begins to dry out and scab. as the scab dries it shrinks, drawing the sides of the cut together
collagen is deposited under the scab
stem cells in the epidermis undergo mitosis to form new cells
new blood vessels grow to supply oxygen to the tissues
64
what is the role of mast cells in inflammation?
detects the presence of microbes in tissues and release histamines and cytokines
65
effects of histamines
cause vasodilation to make capillary walls more permeable to white blood cells and proteins
causes an increase in tissue fluid leading to swelling
excess tissue fluid drains into the lymphatic system where lymphocytes are stored
66
role of cytokines
cytokines (cell chemicals) attract phagocytes to the area
67
how do fevers act as a defence against pathogens?
higher temperatures inhibit pathogen reproduction
immune system works faster at higher temperatures
68
how do fevers occur?
cytokines stimulate the hypothalamus to reset the body thermostat which is why temperature goes up
69
what type of white blood cell are neutrophils?
phagocyte
70
what type of white blood cell are macrophages?
phagoctyes
71
function of neutrophils
able to squeeze through capillaries to patrol tissues
first defenders on the scene of a bacterial invasion
72
role of macrophages
leave the bone marrow and travel in the blood as monocytes which develop into macrophages once they settle in the organs
become antigen presenting cells
73
function of cytokines
increase body temperature
attract phagocytes to the area
stimulate specific immune system response (lymphocytes)
74
antigens
are chemicals on the surface of cells made of proteins or glycoproteins which allow the body to recognise as "self" or forgein like a pathogen
75
function of opsonins
are chemicals that tag pathogens by binding to the antigens so that they are easily identified and engulfed
76
phagocytosis in neutrophils
1. opsonins attach to antigens on the surface of a pathogen
2. receptors on the neutrophil attach to the opsonins on the pathogen
3. neutrophils engulf a pathogen in a vesicle (phagosome)
4. lysosome fuse with the phagosome forming a phagolysosome
5. hydrolytic enzymes in the lysosome completely digest the pathogen into soluble molecules that diffuse into the cytoplasm or released by exoytosis
77
antigen presentation (phagocytosis in macrophages)
1. antigen on pathogen attached to receptor on macrophage
2. pathogen is engulfed and enclosed in a vesicle (phagosome)
3. lysosomes fuse with phagosome forming a phagolysosome
4. pathogen is partially digested by hydrolytic enzymes: some product is absorbed into cytoplasm; the other fragments are presented on the surface
5. indigestible material is removed by exocytosis the macrophage is now an antigen presenting cell
78
what is the difference between phagocytosis in neutrophils and macrophages?
neutrophils completely digest pathogens (non-specific) and macrophages partially digest pathogens (specific)
79
what is the purpose of antigen presentation?
the antigens presented on the surface act as a signal to lymphocytes
80
where are T lymphocytes made?
bone marrow
81
where do T lymphocytes mature?
thymus gland
82
T lymphocyte activation
1. antigen presentation occurs
2. each T lymphocyte has a different receptor, when the complementary receptor binds, the antigen presenting cell releases cytokines that active the specific T lymphocyte (clonal selection)
3. the activated T lymphocytes divide by mitosis forming a clone of indentical cells (clonal expansion)
83
what type of immunity is T lymphocyte activation?
cell mediated immunity
84
function of T helper lymphocytes
secrete cytokines (interleukins) which bind to specific receptors on target cells; they act over short distances
85
function of T killer lymphocytes
produce a chemical called perforin which creates pores in the cell membrane so it is freely permeable which destroys the cell
86
function of T memory cells
remain in the blood and help the body to respond more quickly and effectively if the same antigen enters again by dividing rapidly to form clones of T cells
87
where are B lymphocytes made?
bone marrow
88
where do B lymphocytes mature?
bone marrow
89
what type of immunity is B lymphocyte activation?
humoral immunity
90
B lymphocyte activation
1. when a specific B lymphocyte encounters an antigen which is complementary to its antibodies it becomes activated. T helper cells help activate some by releasing interleukins (clonal selection)
2. the activated B lymphocytes divide by mitosis (clonal expansion)
3. B lymphocytes differentiate into plasma cells which produce antibodies (differentiation)
91
how are plasma cells different to B lymphocytes?
contain more organelles;
synthesise the particular antibody they make;
release antibodies by exocytosis;
only live for a few weeks;
92
function of B memory cells
remain in the blood, if the same antigen invades again the memory cells will develop into plasma cells that produce the correct antibody
93
what are immunoglobulins?
antibodies
94
features of antibodies
- composed of glycoproteins
- consist of 4 polypeptide chains
- has a variable region that can bind to a specific antigen
95
constant region
the area on an antibody that is the same on all antibodies; phagocytes have specific receptors to this region
96
function of hinge region
allows flexibility in binding to more than one antigen
97
function of disulphide bridges
hold polypeptide together
98
opsonisation
opsonins (antibodies) bind to antigens on pathogen; constant region acts as a binding site for phagocytosis
99
agglutination
occurs in large antibodies where they bind pathogens together which makes bacteria easier to engulf and prevents viruses entering host cells
100
how do antibodies act as anti toxins?
antibodies bind to toxins produced by pathogens making them harmless
eg by changing shape or covering part of the toxin
101
neutralisation
antibodies bind to the surface of pathogens and prevent it from binding to host cells
102
why is the immune response after encountering a pathogen for the second time faster?
memory cells allow for a faster clonal selection, expansion and differentiation; antibodies are produced much faster and in much larger numbers
103
immune response
the specific response to antigens on a pathogen, involving lymphocytes and antibodies
104
autoimmune disease
failure to distinguish between self and non-self antigens resulting in antigens being produced against the antigens on own cells
105
what causes autoimmune diseases?
specific lymphocytes not being destroyed during development
106
examples of autoimmune diseases
rheumatoid arthritis, type 1 diabetes
107
natural passive immunity
body naturally recieves antibodies ie through breast milk
108
artifical passive immunity
injection with antibodies
109
natural active immunity
body making antibodies after being exposed to the disease
110
artificial active immunity
vaccinations
111
vaccination
deliberate exposure to antigenic material that has been made harmless which causes an immune response
112
forms of antigenic material in vaccines
- whole, live microorganisms
- attenuated (weakened) pathogen
- dead pathogen
- antigens
- toxoid (harmless version of a toxin)
- mRNA
113
herd vaccination
vaccinating enough people to provide immunity to all the population at risk
114
ring vaccination
when a new case of a disease is reported, all possible contacts of the infected person are vaccinated to prevent spread
115
reasons for changing vaccines
- antigens keep changing
- pathogens evolve to avoid detection which can make vaccines useless
- pathogens with a high mutations rate are difficult to vaccinate against
116
reasons for changing vaccination programmes
- new disease arising or becoming more severe may need new vaccines
- research may lead to a new vaccine
- programmes may be altered due to improved understanding of how long immunity lasts or who is at risk
117
why are new drugs needed?
- new diseases are emerging
- many diseases still have no treatment
- some antibiotics are ineffective
118
sources of new medicines
microorganisms - fungi and bacteria as sources of antibiotics;
plants - foxgloves containing digitalis to treat abnormal heart rhythms;
personalised medicines - sequencing genomes to determine specific drugs to be used for the conditon;
119
effect of overuse and misuse of antibiotics
results in microbes that are resistant to antibiotics ie some bacteria are resistant to a range of antibiotics eg MRSA
