Communicable Disease Flashcards
(85 cards)
1
Q
What is a pathogen
A
A microorganism that causes disease
They live by taking nutrition from their host, but also causing damage in the process
The organism that they live in is called the host.the host body creates a good habitat
2
Q
Describe bacteria
A
Their cells are smaller than eukaryotic cells but they an reproduce rapidly.their presence can cause disease by damaging cells or by releasing waste products or toxins to the host.
3
Q
In plants , bacteria usually live in ?
A
The vascular tissues and cause blacking and death to tissues
4
Q
Describe fungi
A
Can cause disease in both plants and animals. There are common fungal infections where the fungus lives in the skin of an animal and where it’s hyphae , which forms a mycelium , grows under the skin surface. The fungi can send out specialised reproductive hyphae which grow to the surface of the skin to release spires , causing redness and irritation
In plants the live in the vascular tissues to gain nutrients. The hyphae releases extra cellular enzymes to digest surrounding tissue which causes decay
5
Q
Describe viruses
A
Causes disease in both plants and animals. Viruses invade cells and take over the genetic machinery and other organelles of the cell . They then cause the cell to manufacture more copies of the virus, the host cell eventually bursts, releasing many more viruses which will infect healthy cells .
6
Q
Describe protoctista
A
Causes diseases , theses organisms usually cause harm by entering host cells and feeding on the contents as they grow
7
Q
Tuberculosis
Characteristics and organisms that cause disease
A
Affects many parts of the body , killing the cells and tissues
Bacteria
8
Q
Bacterial meningitis
Characteristics and organisms that cause disease
A
Infection of the meninges - the membranes that surrounds the brain and spinal cord , the membranes become swollen and may cause damage to the brain and nerves
Bacteria
9
Q
Ring rot in plants
Characteristics and organisms that cause disease
A
Ring of decay in the vascular tissue of a potato Tuber or tomatoes , accompanied by leaf wilting
Bacterium
10
Q
HIV/AIDS
Characteristics and organisms that cause disease
A
Attack cells in the immune system and compromises the immune response
Virus
11
Q
Influenza
Characteristics and organisms that cause disease
A
Attacks the respiratory system and causes muscle pains and headaches
Virus
12
Q
Tabacco mosaic virus
Characteristics and organisms that cause disease
A
Causes mottling and discolouration of leaves
Virus
13
Q
Black Sigatoka
Characteristics and organisms that cause disease
A
Causes leaf spots on banana plants reducing yield
Fungus
14
Q
Blight
Characteristics and organisms that cause disease
A
Affects both leaves and potato tubers
Protoctistan
15
Q
Ringworm
Characteristics and organisms that cause disease
A
Growth of fungus in skin with spores case erupting through skin to cause a rash
Fungus
16
Q
Athletes foot
Characteristics and organisms that cause disease
A
Growth under skin of feet
Fungus
17
Q
Malaria
Characteristics and organisms that cause disease
A
Parasite in the blood that causes headaches and fever and may progress to coma and death
Protoctistan
18
Q
What is the pathogen life cycle
A
- travel from one host to another
- entering the hosts tissues
- reproducing
- leaving the hosts tissue
19
Q
Define direct transmission
A
Passing a pathogen from host to new host , with no intermediary
20
Q
Define indirect transmission
A
Passing a pathogen from host to new host via a vector
21
Q
Define transmission
A
Passing a pathogen from an infected individual to an uninfected individual
22
Q
What is a vector
A
An organism that carries a pathogen from one host to another
23
Q
What are the 4 types Kms means of transmission
A
- direct physical contact , touching a person who is infected or contaminated surfaces that harbour the pathogens
- Faecal oral transmission , usually by eating or drinking contaminated food by pathogens
- droplet infection , pathogen carried in tiny water droplets in the air
- transmission by spores , resistant stage of the pathogen , Carried in the air
24
Q
Factors that affect transmission
A
Hygiene, washing hands
Human sewage
Cover mouth when coughing and sneezing
25
Social factors which affect transmission
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Over crowding
Poor ventilation
Poor Health
Poor diet
Homelessness
Living with people who have migrated from areas where disease is common
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26
Explain transmission of plant pathogens
They can be spread by direct and indirect means
Many pathogens are presented in the soil and will infect plants by entering the roots , many fungi produce spore as a means of sexual or asexual reproduction . These spores may be carried in the wind (airborne transmission )
Once a pathogen is inside the plant it may infect the vascular tissue . Pathogens in the leaves are distributed when the leaves are shed and carry pathogens back to the soul where it can grow and infect another plant . Pathogens can also enter the fruit and seeds and then be distributed with the seeds so that many or all the offspring are infected
27
How climate affects pathogens
Many protoctists , bacteria and fungi can grow and reproduce more rapidly in warm and moist conditions , so there more common in warmer climates
I'm cooler climates these pathogens can be damaged or killed by cold weather- it reduces ability to grow and reproduce
28
Explain passive defences jn plants
Theses are defences present before infection , and their role is to prevent entry and spread of the pathogen
29
Name and explain the physical defences in plants
- cellulose cell wall , a physical barrier and contains a variety of chemical defences that activate when a pathogen is detected
- lignin thickening of cell walls , waterproof and undigestible
- waxy cuticles , prevent water collecting on cell surfaces to stop pathogens
- bark , contains a variety of chemical defences
- callose , polysaccharide around that's deposited in sieve tubes , plates in sieves tubes and blocks the flow , can prevent a pathogen spreading around the plant
- tylose , a balloon like swelling or projection that fills the xylem when it's fully formed , it plugs the vessel and vessels can no longer carry water , prevents spread of pathogen.
30
Describe active defences in plants
When pathogens attack , specific chemicals in their cell walls can be detected by the plant cells . The plant responds by fortifying the defences already present , these include increasing the physical defences and producing defensive chemicals
31
What are the active defences in plants
Cell walls become thickened and strengthened with additional cellulose
Deposition of callose between the plant cell wall and cell membrane near the invading pathogen . Callose deposited are polysaccharide that impede cellular penetration at the site of injection . It strengthens the cell walls and blocks plasmodesmata
Oxidative bursts that produce highly reactive oxygen molecules capable of damaging the cells of invading organisms
Increase in production of chemicals
32
Describe terpenoids
A range of essential oils that have antibacterial and anti-fungal properties . They may also create scent
33
Describe phenols
These have antibiotic and antifungal properties . These compounds bind to salivary proteins and digestive enzymes
34
Describe alkaloids
Nitrogen containing compounds. These give a bitter taste to inhibit herbivores feeding . They also act on a variety of metabolic reactions via inhibiting or activating enzyme actions .
35
Describe defensive proteins (chemicals )
These are small cysteine rich proteins that have broad anti microbial activity
36
Describe hydrolytic enzymes (chemicals )
These are found in the spaces between cells . They include chitinase , glucanases and lysozyme
37
What is necrosis
Deliberate cell suicide . A few cells are sacrificed to save the rest of the plant
38
The primary defences against pathogen in animals include
The skin
Blood clotting and skin repair
Mucus membranes
Coughing and sneezing
Inflammation
39
Describe how the skins function as a primary defence
The body is covered by skin , the outer layer of the skin is called the epidermis and consists of layers of cells . Most of these cells are called keratinocytes. These cells are produced by mitosis.they then migrate out the surface of the skin . As they migrate they dry out and the cytoplasm is replaced by the protein keratin , this process is called keratinisation . The keratinised layer of dead cells acts as an effective barrier to pathogens
40
Explain blood clotting
Damage to blood vessel , inactive thrombokinase - active thrombokinase , prothrombin , active Thrombin , soluble fibrinogen , insoluble fibrin , fibres attack to platelets in plug , clot
41
Explain mucus membranes
The epithelial layer contains mucus secreting cells called goblet cells. In the airways the mucus lines the passages and traps pathogens that may be in the air. The epithelium also has ciliated cells which waft the layer of mucus along , they move the mucus up to the top of the trachea where it can enter the oesophagus . It is then sealed and passes down the digestive system . Most pathogens in the digestive system are killed by the acidity of the stomach - this denatures the pathogens enzymes
42
Describe coughing and sneezing
Areas that are prone to attack are also sensitive. They respond to the irritation that may be caused by the presence of microorganisms or the toxins that they release. These reflexes include coughing and sneezing and vomiting . In a cough or a sneeze the sudden expulsion of air will carry with it the microorganism causing the irrigation
43
Describe inflammation
One sign of inflammation is swelling and redness
The presence of microorganisms in the tissue is detected by specialised cells called mast cells. These cells release a cell signalling substance called histamine . Histamine has a range of effects on the surrounding tissue which act to help combat the infection . The main effect is to cause vasodilation and make the capillary walls more permeable to white blood cells and some proteins . Blood plasma and phagocytic white blood cells leave the blood and enter the tissue fluid . This leads to increased production of tissue fluid , which causes the swelling . Excess tissue fluid is drained into the lympatic system where lymphocytes are stored . This can lead to pathogens coming into contact with the lymphocytes and initiating specific immune responses
44
Secondary defences are used to
Combat pathogens that have entered the body . When a pathogen invades the body it is recognised as foreign by the chemical markets on its outer membrane , these markers are called antigens . They are proteins or glycoproteins intrinsic o the plasma membrane
45
What are opsonins
Are protein molecules that attach to the antigens o the surface of a pathogen . They are a type of antibody . Some opsonins are not very specific so that Thie can attach to a variety of pathogenic cells . The role of the opsonins is to enhance the ability of phagocytic cells to bind and engulf the pathogen
46
What are the two types is phagocytes
Neutrophils
Macrophages
47
Describe neutrophils
Multi loves nucleus
Manufactured in bone marrow
Travel in the blood and often squeeze out the blood into tissue fluid
Short lived but they will be released in large number as a result of pathogen
Contain large numbers of lysosomes
They engulf and digest pathogens
Dead neutrophils may collect in an area of infection to form pus
48
Describe the neutrophils stages
- neutrophils binds to the opsonins attached to the antigen on the pathogen
- the pathogen is engulfed by endocytosis forming a phagosome
- lysosomes fuse to the phagosome and release lytic enzymes into it
- after digestion the harmless products can be absorbed Into the cell
49
Describe macrophages
Larger cells manufactured in the bone marrow
Travel in the blood as monocytes
Many are found in the lymph nodes where they mature into macrophages
They play an important role in initiating the specific response to invading
50
Describe the macrophages stage
When a macrophages engulfs a pathogen it does but fully digest it . The antigens from its surface of the pathogen is saved and moved to a specific protein complex on the surface of the cell. The cell becomes an antigen presenting cell, it exposes the antigen on its surface so that other cells of the immune system can recognise the antigen . The special protein complex ensure that the antigen presenting cell is not mistaken for a foreign cell and attack by other phagocytes
51
What are the two types of lymphocytes
B cells
| T cells
52
What Four types of cells do T lymphocytes develop or differentiate into
T helper cells
T killer cells
T memory cells
T regulator cells
53
Describe the T helper cells
Release cytokines that stimulate the B cells to develop and stimulate phagocytosis by the phagocytes
54
Describe T killer cells
Which attack and kill host body cells that display the foreign antigen
55
Describe T memory cells
Provide long term immunity
56
Describe T regulator cells
Shut Down the immune response after the pathogen has been successfully removed , they are involved in preventing autoimmunity
57
What are the two of cells that B lymphocytes develop into
Plasma cells
| B memory cells
58
T cells are activated When
A foreign antigen is in contact with a host cell
59
What are example or communication using cytokines
Macrophages release monokines . Some monokines attract neutrophils and others stimulate B cells to differentiate and release antibodies
T cells and macrophages release interleukins which can stimulate the clonal expansion and differentiation of B and T cells
60
What is autoimmune disease
An autoimmune disease occurs when the immune system attacks a part of the body . Normally any B or T cells that are specific to our own antigens are destroyed during early development of the immune system . An autoimmune disease arises when antibodies start to attack our own antigens - possibly because antigens that are bit normally exposed to attack
61
What are the three stages of the specific immune response
Clonal selection
Clonal expansion
Differentiation
62
Describe clonal selection
An invading pathogen has specific antigens , in order to trigger the immune response these must be detected by T and B cells lymphocytes that carry the specific receptor molecules on their plasma membranes . The receptor molecules are proteins that have the shape that is complementary to the shape of the antigen , contact between the antigen and the lymphocytes can be achieved directly when pathogenic cells enter the lymph nodes or by the action of antigen presenting cells
63
Describe clonal expansion
Once the correct lymphocytes have been activated they must increase in numbers to become effective , they achieve this by mitotic cell decision
64
Describe differentiation
The B and T lymphocytes do not manufacture the antibodies directly , once selected clones of the lymphocytes develop into a range of useful cells
65
Describe the structure of an antibody
```
Light polypeptide bond
Heavy polypeptide bond
Disulfide bond/ bridge
Hinge region
Variable region
Constant region
```
66
Describe the variable region on an antibody
Has a shake specific the the shape Of the antigen
67
Describe the constant region of an antibody
It may Have a site for the easy binding of phagocytic cells
68
Antibodies work in. A variety of ways , but must act by attaching to the antigens on a pathogen , what are the three main groups
Opsonins
Agglutinins
Anti toxins
69
Describe anti toxins
Some antibodies bind to molecules that are released by pathogenic cells , these molecules may be toxic and the action of the anti toxins renders them harmless
70
Describe agglutinins
Because each antibody molecule has two identical binding sites it is able to cross link pathogens by binding an antigen on one pathogen with one binding site and then an antigen on another pathogen with its other binding site . When many antibodies perform this cross linking they clump together pathogens . This has two advantages 1- the pathogens are physically impeded from carrying out some functions 2- the pathogens are readily engulfed by phagocytes
71
Describe opsonins
Are a group of antibodies that bind to the antigens on a pathogen, they act as a binding site for phagocytic cells so that these can more easily bind and destroy the pathogen.
Some opsonins are not very specific and stick to types of molecules that are not found in the house cell
Other opsonins are produced as part of the specific immune response and bind to a very specific antigens . The pathogen may have another use for this antigen molecule e.g. It may be a binding site used for attachment to the host cell , the opsosnin bound to the antigen renders it useless . The opsonins assets in phagocytosis but also prevents the pathogen entering a host cell before it can be attached by phagocytes
72
Describe the primary and secondary response time on a graph
When an infecting agent is first detected , the immune system starts to produce antibodies . But it takes a few days before the number of antibodies in the blood rises to a level that can combat the infection successfully- this is known as the primary response . Once the pathogens have been felt with , the number of antibodies in the blood drops rapidly
If the body is infected a second time by the same pathogen the antibodies must be made again , however as a result of specific immune response there will be B memory cells and T memory cells circulating in the blood . These cells will recognise the specific antigens and the immune system can swing into action more quickly, this time the production of antibodies starts sooner and is much more rapid . So the concentration of antibodies rises sooner and reaches a higher concentration - this is known as secondary immune response , it is usually quick enough to prevent nag symptoms being detected by the host
73
What is a vaccination
A way of stimulating an immune response so that immunity is achieved
74
The antigenic material used in vaccinations can take a variety of forms , what are they
- whole live microorganisms
- harmless or weakened version of pathogenic organism
- a dead pathogen
- a preparation of the antigens from s pathogens
- a toxoid
75
What are the two application types of vaccines
Herd
| Ring
76
Describe herd vaccination
Is using a vaccine to provide immunity to all or almost all of the population at risk once enough people are immune the disease can no longer be spread through the population and you achieve herd immunity. In order for it to be effective it is essential to vaccinate almost all the population
77
Describe ring vaccination
Is used when a new case of a disease is reported. It involves vaccinating all the people in the immediate vicinity of the new case . This may mean vaccinating the people in the surrounding houses , or even in the whole village or town .
78
What is active immunity
Where the immune system is activated and manufactures its own antibodies
79
What is artificial immunity
Immunity that is achieved as a result of medical intervention
80
What is natural immunity
Immunity achieved through normal life processes
81
What is passive immunity
Immunity achieved when antibodies are passed to the individual through breast feeding or injection
82
New drugs are needed because
- new diseases are emerging
- there are still many diseases for which there are no effective treatments
- some antibiotics are becoming less effective
83
What are antibiotics
A chemical which prevents the growth of microorganism
84
What are personalised medicines
the development of designer medicines for individuals
85
What is synthetic biology
The reengineering of biology , this could be the production of new molecules that mimic natural processes , or the use of natural molecules to produce new biological systems that do not exist in nature
