Communicable Diseases, 4.1 Flashcards
1
Q
Define healthy
A
Free from disease, mentally, socially and physically well
2
Q
What is a pathogen?
A
Microorganism that causes disease
3
Q
How does a pathogen survive?
A
By taking nutrients from the ‘host’ causing damage in the process
4
Q
How does bacteria cause disease?
A
- Enters host and reproduces quickly
- Damages cells or releases toxins which are toxic to the host
- In plants bacteria live in vascular tissues causing blackening and death
5
Q
Give an example of a bacteria that causes disease in humans
A
Tuberculosis - kills cells and tissues, the lungs are most often affected.
6
Q
Give an example of a bacteria that causes disease in plants
A
Ringrot - ring of decay in vascular tissue in a potato tuber
7
Q
How does fungi cause disease?
A
- Fungus live under the skin where its hyphae grow under the skins surface
- Can send out specialized hyphae which grow to the surface and release spores
- Plants, in vascular tissue releases cellulase to digest
8
Q
Give an example of a fungi that causes disease in humans
A
Athletes foot growth under the skin of feet
9
Q
Give an example of a fungi that causes disease in plants
A
Black sigatoka causes leaf spots on banana plants reducing the yield
10
Q
How do viruses cause disease?
A
- Invade cells and take over the genetic machinery and other organelles
- Host cell eventually bursts releasing new viruses
11
Q
Give an example of a virus that causes disease in humans
A
HIV/AIDs attacks cells in the immune system and compromises immune response
12
Q
Give an example of a virus that causes disease in plants
A
Tobacco mosaic virus causes discolouration of leaves
13
Q
How do protoctista cause disease?
A
Enter host cells and feed on the contents as they grow
14
Q
Give an example of a protoctista that causes disease in humans
A
Malaria - parasite in the blood causing fever coma and death
15
Q
Give an example of a protoctista that causes disease in plants
A
Blight - affects leaves and potato tubers
16
Q
What is direct transmission?
A
Passing pathogen from host to host directly no intermediary
17
Q
How are diseases passed through physical contact and how do we stop it?
A
Touching an infected person - need to wash hands or surfaces, sterilise and disinfect and use condoms
-eg HIV, bacterial meningitis, ring worm, athletes foot
18
Q
How are disease passed through faecal-oral transmission and how can we stop it?
A
Drinking/contact with contaminated water - need treatment of waster water and drinking water, was fresh food
-eg cholera, food poisoning
19
Q
How are disease passed through droplet infection and how do we stop it?
A
Through coughing and sneezing - need to catch it, bin it, kill it, cover mouth
-eg influenza, tuberculosis
20
Q
How are diseases passed through spores and how do we stop it?
A
Contact with spores in soil - need to use a mask and wash skin
-eg tetanus, anthrax
21
Q
What is indirect transmission?
A
Passing a pathogen from host to host via a vector
22
Q
What is a vector?
A
Organism that carries a pathogen
23
Q
What is an example of indirect transmission?
A
Malaria
24
Q
What is malaria?
A
A plasmodium parasite is able to enter the host when a female Anophele mosquito bites them
25
Describe the stages of malaria
1. Plasmodium migrates and enters liver cells
2. Multiplies then returns to the blood stream
3. Invades the red blood cells, feeds on haemglobin (can remain dominant for some time)
4. If plasmodium bursts out this causes fever
26
How is malaria passed from one person to another?
If a second mosquito bites an infected person the mosquito becomes infected and when the mosquito bites another person it passes it onto the next person
27
Why do white blood cells struggle to deal with plasmodium?
It is large so can't digest it
28
Describe direct transmission in plants
- pathogens are in the soil and infect via damaged root
- Fungi sports carried in the wind
- Pathogens could enter vascular tissue
- Pathogens are redistributed
29
Describe indirect transmission in plants
- Insect attacks, spores are attached to burrowing beetles
| - Dutch elm disease carried by a beetle
30
What factors affect transmission?
- Over crowding and poor ventilation
- Poor health, diet and lifestyle
- Warm and damp climates
31
How does skin act as a primary defense?
- Surface is a layer of dead cells
- Process called Keratinisation
- Secretes sebum, waterproof
- 20-30 cells thick
32
How do mucous membranes act as primary defense?
- Goblet cells secrete sticky mucus
| - Surfaces lined with cilia to move mucous with trapped pathogens out
33
How does coughing and sneezing act as primary defense?
Expels air to get rid of pathogens
34
Why is blood clotting important?
Cuts leave the body open to infection - a blood clot forms a scab to pull the skin back together
35
Describe the process of blood clotting.
1. Collagen fibres exposed, platelets stick to these, form a plug
2. Platelets become activated and release clotting factors (thromboplastins)
3. Thromboplastins convert to prothrobin then to thrombin - through an enzyme cascade which requires calcium ions
4. Thrombin catalyses the conversion of fibrinogen into insoluble fibrin
5. Fibrin forms a mesh trapping red blood cells forming a clot - dries out to form a scab
36
Describe the process of inflammation.
- Presence of microorganisms in the tissue detected by mast cells
- Release cell signalling substance, histamine, combat infection
- Causes vasodilation and makes capillary walls more permeable to white blood cells and proteins
- Increased production of tissue fluid which leads to swelling
- Tissue fluid drained into lymphatic system meaning pathogens come into contact with lymphocytes
37
How are the eyes protected from infection?
Antibodies and enzymes in tear fluid
38
How are ears protected from infection?
Ear canal lined with wax
39
Define antigen
A membrane bound molecule use to recognize pathogens
40
Define phagocytes
Specialised cells in the blood that engulf and digest pathogens
41
Define Neutrophils
Most common phagocytes from bone marrow, contain lysosomes to engulf and digest pathogens
42
Define macrophage
Large cells which engulf pathogens but don't fully digest, cell becomes an antigen presenting cell
43
Define antibody
Specific protein released that attaches and attacks pathogens antigens
44
Define lymphocyte
White blood cell
45
Define Opsonins
Proteins that bind to antigens, sometimes not specific. Enhance ability of phagocytic cells.
46
Define phagocytosis
Specialised cells that digest pathogens
47
How are pathogens recognised by the body?
By antigens - unique to the pathogen and foreign to the immune system
48
What is non-specific immune response?
Phagocytes that engulf any pathogen
49
What is specific immune response?
Response to a specific pathogen/antigen which involves the production of antibodies by lymphocytes
50
What is meant by antigen presentation?
Macrophage (Antigen presenting cell) - engulfs infected cell and presents the antigens. Moves around the body until it comes into contact with T or B lymphocytes
51
Where are T and B lymphocytes made?
Bone marrow
52
Where do B lymphocytes mature?
Bone marrow
53
Where do T lymphocytes mature?
Thymus
54
What is activation of T and B lymphocytes called?
Clonation
55
What are the different division of B lymphocytes?
Plasma cells and B memory cells
56
What is the role of the (B) plasma cells?
Manufacture and release antibodies
57
What is the role of B Memory cells?
Remain in the body after the pathogen is destroyed and act as immunological memory
58
What are the different divisions of T lymphocytes?
T Killer cells. T Memory cells. T Helper cells. T Regular cells.
59
What is the role of T Killer cells?
Attack and kill body cells that display a foreign antigen
60
What is the role of T memory cells?
Provide long term immunity
61
What is the role of T helper cells?
Release cytokines which stimulate B cells to divide and stimulate phagocytosis
62
What is the role o T regulator cells?
Shut down immune response after the pathogen is destroyed
63
What does cell signalling in the immune system involve?
Release of chemicals called cytokines. Detect signals the cell must have a cell surface receptor.
64
What do macrophages release? And what does it do?
Monokines. Attract neutrophils or stimulate B cells to differentiate
65
What do T cells and macrophages release? And what does it do?
Interlukins. Stimulates clonal expansion of T and B cells
66
What is inferon and what does it do?
It's a cell signalling chemical. Inhibits virus reproduction and stimulates T killer cells
67
Describe how B lymphocytes work.
- B lymphocytes bind with antibody complementary to the antigen (on pathogen or APC)
- Stimulated B lymphocytes divide many times
- Produced by memory cells so there is an excess of antibodies
68
Describe how T helper cells work.
- T helper cells bind with antibody complementary to the antigen (on pathogen or APC)
- Stimulated T lymphocytes divides many times
- T helper cells secrete cytokines which stimulate phagocytic cells and other lymphocytes
69
Describe how T killer cells work.
- T killer cells bind with antibody complementary to the antigen (on pathogen or APC)
- Stimulated T killer cells divide many times
- T killer cells bind to cells presenting the complementary antigen and kill them
70
What is an autoimmune disease?
Occurs when the immune system attacks part of the body - anitbodies attack our antigens
71
What is arthritis?
Painful inflammation of a join - antibodies attack membrane around the joint
72
What is lupus?
Causes swelling and pain - antibodies attack proteins in the cells nucleus
73
What is the hinged region in an antibody?
Allows flexibility so the antibody can grip onto the antigen
74
What is the variable region in an antibody?
Variable region shape specific to the shape of the antigen
75
What is the constant region in an antibody?
The same for all antibodies
76
Describe the process of neutralization by antibodies?
Antibodies bind to antigens to stop them entering body cells (opsonins)
77
Describe the process of agglutination by antibodies?
- Antibodies bind to the surface of several pathogens clumping them together
- Macrophages can recognize them and easily destroy by phagocytosis
78
Describe the process of antitoxins by antibodies
- Some pathogens release molecules which may be toxic
| - Antibodies bind to them an release antitoxins
79
What is natural immunity?
Active - infection. Passive - maternal.
80
What is artificial immunity?
Active - vaccination. Passive - antibody transfer.
81
What does a vaccine do?
Stimulates the production of white blood cells and antibodies
82
What does a vaccine contain?
- Harmless toxins (tetanus)
- Attenuated form of the pathogen
- Isolate antigens such as cell surface proteins
- Dead pathogen
- Live pathogen with similar antigens which are not as harmless
83
What is antigenic variation?
Ability to change their proteins due to mutations
84
What is herd vaccination?
- Provides immunity to the majority of the population
- If enough people are immune the disease can no longer spread
- Vaccinate almost all of the population 80%-90%
85
What is ring vaccination?
- When there's a new disease
| - Vaccinate everyone in the immediate vicinity of the new disease
86
What is an epidemic?
Rapid spread of disease through a high proportion of the population
87
Why do we need new drugs?
New diseases. Diseases with no effective treatments. Antibiotics becoming less effective.
88
What is an example of accidental discovery of a drug?
Antibiotic penicillin by Alexander Flemming
89
What are traditional remedies?
Drugs that have been used for centuries eg morphine and opium
90
How do we get medicine from observing wildlife?
Many animals use plants with medicinal properties. Scientists use traditional plants and animal behavior when developing new drugs
91
How can we use drugs to stop HIV?
If we can block the binding of the pathogen to the receptor site then it cannot enter the cell
92
What is personalised medicine?
- It is possible to screen genomes of plants or microorganisms to identify potential medicinal compounds from DNA sequences
- Could be able to sequence the genes and develop scientific drugs for the condition
93
What is synthetic biology?
Development of new molecules that mimic biological systems
94
What are some examples of physical plant defenses?
- Cellulose cell wall, physical barrier
- Lignin, thickens cell wall and is waterproof
- Waxy cuticles, prevent water collecting on cell surfaces
- Bark, contains a variety of chemical defences
- Stomatal closure, stomata are controlled by guard cells which can open and close
- Callose, large polysaccharide deposited in sieve tubes at the end of growing season
- Tylose, balloon like swelling that fills the xylem vessel and block it
95
What are terpenoids?
Oils with antibacterial properties and antifungal properties
96
What are phenols?
Inhibit insect attacks, tannin, do no grow an eventually die
97
What are active defenses in plants?
- Production of chemicals requires energy (proteins/glycolipids)
- Cell walls thickened and strengthened with cellulose
- Callose, blocks plasmodesmata
