Module 4.1 - Communicable Diseases Flashcards
1
Q
Characteristics of tuberculosis
A
Affects many parts of the body
Kills cells and tissues
Lungs are most often affected
2
Q
Characteristics of ring rot (plants)
A
Ring of decay in the vascular tissue (xylem/phloem) of a potato tuber or tomato
Leaf wilting
3
Q
Organism that causes athlete’s foot
A
Fungus
Trichophyton rubrum
5
Q
Characteristics of HIV/AIDS
A
Attacks cells in the immune system
Compromises the immune system
6
Q
Characteristics of influenza
A
Attacks respiratory system
Causes muscle pains and headaches
7
Q
Organism that causes tobacco mosaic virus
A
Virus
Tobacco mosaic virus
9
Q
Organism that causes blight (tomatoes and potatoes)
A
Protoctistan
Phytophthora infestans
10
Q
Characteristics of black Sigatoka (bananas)
A
Causes leaf spots on banana plants reducing yield
11
Q
Organism that causes ringworm (cattle)
A
Fungus
Trichophyton verrucosum
13
Q
Characteristics of blight (tomatoes and potatoes)
A
Affects both leaves and potato tubers
15
Q
Organism that causes bacterial meningitis
A
Bacteria
Neisseria meningitidis
Streptococcus pneumonia
17
Q
Characteristics of athlete’s foot
A
Fungus growth under skin of feet, particularly between the toes
18
Q
Characteristics of malaria
A
Parasite in the blood that causes headache and fever
May progress to coma and death
19
Q
Organism that causes tuberculosis
A
Bacteria
Mycobacterium tuberculosis
M. bovis
20
Q
Organism that causes ring rot (in plants)
A
Bacterium Clavibacter michiganensis (subspecies of sepedonicus)
21
Q
Organism that causes HIV/AIDS
A
Virus
Human immunodeficiency virus
22
Q
Organism that causes malaria
A
Protoctistan Plasmodium falciparum P. vivax P. ovale P. malariae
24
Q
Organism that causes black Sigatoka (in bananas)
A
Fungus
Mycosphaerella fijiensis
25
Q
Organism that causes influenza
A
Virus
From family Orthomyxoviridae - ‘flu’ viruses
28
Q
Characteristics of ringworm (cattle)
A
Growth of fungus in skin with spore cases erupting through skin to cause a rash
37
Q
Characteristics of tobacco mosaic virus
A
Causes mottling and discolouration of leaves
38
Q
Characteristics of bacterial meningitis
A
Infection of the meninges - membranes that surround the brain and spinal cord
Membranes become swollen and may cause damage to the brain and nerves
39
Q
Types of pathogen
A
Bacteria
Virus
Fungi
Protoctist
40
Q
Define pathogen
A
A microorganism that causes disease
41
Define communicable disease
A disease that can be spread between people
42
Main points about bacteria
Prokaryotic (smaller than eukaryotes)
Reproduce rapidly
Damage cells through release of toxins
43
Main points about fungi
Often live in skin
Hyphae form mycelium
Reproductive hyphae grow into skin and release spores (redness to skin)
In plants, lives in vascular tissue to gain nutrients
Hyphae release extracellular digestive enzymes to break down cellulose, decaying the plant
44
Main points about protoctista
Enters host and feeds on contests of the cell
| Malaria parasite Plasmodium has immature forms which feed on haemoglobin
45
Main points about viruses
Invade cells and take over genetic machinery and other organelles
Causes the cell to make more copies of the virus
Host cell ruptures, releasing new invading viruses
46
Life cycle of a pathogen
Transmission (travel from one host to another)
Enters host’s tissues
Reproduces
Leaves host’s tissues
47
Direct transmission of pathogens in animals
Direct physical contact
Faecal-oral
Droplet infection
Spores
48
Points about direct physical contact
Touching contaminated person or surface
E.g. HIV, bacterial meningitis, ringworm, athlete’s foot
Factors affecting transmission: hygiene (wash hands regularly); keep surfaces clean (door handles); clean and disinfect cuts; sterilise surgical instruments; wear a condom during sex
49
Points about faecal-oral transmission
Eating/drinking contaminated food/water
E.g. cholera, food poisoning
Factors affecting transmission: treatment of waste and drinking water; wash fresh food with treated water; careful preparation and cooking of food
50
Points about droplet infection
Pathogen is carried in water droplets in the air
E.g. tuberculosis, influenza
Factors affecting transmission: ‘catch it - bin it - kill it’; cover mouth when coughing or sneezing; use a tissue and dispose of it correctly
51
Points about spores
Resistant stage of pathogen
Carried in air or sit on surfaces or in soil
E.g. anthrax, tetanus
Factors affecting transmission: use of a mask; wash skin after contact with soil
52
Define vector
Another organism that may be used by the pathogen to gain entry to the primary host
E.g. Plasmodium parasite enters human via bite from a female Anopheles mosquito; Dutch elm disease via a beetle
53
Transmission of malaria cycle
```
Person has malaria
Gametes of Plasmodium in blood
Female Anopheles mosquito sucks blood
Plasmodium develops and migrate to mosquito’s salivary glands
Uninflected person is bitten
Plasmodium migrates to liver
Plasmodium migrates to blood
Person has malaria, cycle starts again
```
54
Social factors that affect transmission in animals
Overcrowding
Poor ventilation
Poor health (more likely to contract other diseases with HIV/AIDS)
Poor diet
Homelessness
Living/working with people who have migrated from areas where a disease is more common
55
Direct transmission of pathogens in plants
In soil infect plants by entering roots (especially if damaged by replanting, burrowing animals or movement caused by a storm)
Fungi produce spores for sexual or asexual reproduction and these may be carried in the wind - airborne transmission
Pathogens infect vascular tissue
Pathogens in leaves are distributed when leaves are shed and carry the pathogen back to the soil where it can grow and infect another plant
Pathogens can enter fruit and seeds and then be distributed with the seeds so many/all offspring are infected
56
Indirect transmission of pathogens in plants
Insect attack (insect acts as a vector): spores/bacteria attach to burrowing insect which attacks an infected plant; when that beetle attacks another plant, the pathogen is transmitted to un infected plant
57
Effects of climate on disease
Protoctists, bacteria and fungi grow/reproduce faster in warm and moist conditions
More common in warmer climates
Greater variety of diseases in warmer climates
58
Define primary defences
Prevent pathogens from entering the body/blood
59
Define non-specific defences
Trap/kill any kind of pathogen
60
Points about expulsive reflexes
E.g. coughing, sneezing, vomiting
| Irritation from microbes/toxins causes expulsion which carries the microbes with it
61
Process of inflammation
Microbes detected by mast cells which release histamine
Histamine causes vasodilation which makes capillaries more permeable so more white blood cells can leave
More tissue fluid forms as more plasma leaves
This causes swelling (oedema)
Tissue fluid can drain into lymph vessels so pathogens may come into contact with lymphocytes and cause a specific immune response
62
Points about mucous membranes
Primary non-specific defence
At exchange surfaces, the diffusion distances into the blood are small so they are more susceptible to infection from pathogens
Mucous membranes coat these surfaces
Goblet cells produce and secrete mucus in the airways
Cilia waft the mucus to the back of the throat so it can be removes by the body
63
Process of blood clotting and skin repair
Damage to a blood vessel - platelets bind to exposed collagen to form a temporary platelet plug
Platelets also release clotting factors which activate an enzyme cascade
Enzymes cause fibrinogen to form insoluble fibres which attach to the plug
Red blood cells are also trapped, forming a clot
Clot dries and forms a scab which ills the skin closer together
Under the skin collagen is deposited
Stem cells in epidermis divide by mitosis and differentiate to form new skin cells at the edge of the cut
New blood vessels form
When edges of the cut are drawn together the repair is complete
64
What are secondary defences?
They combat pathogens that have already entered the body
65
Define antigen
Protein or glycoprotein belonging to the plasma membrane that is specific to the organism
66
Types of phagocytes
Neutrophils
Macrophages
Antigen-presenting cells
67
Main points about neutrophils
Most common phagocytes
Multi-lobed nucleus
Produced in bone marrow
Travel in blood, often squeeze out of blood into tissue fluid
Short-lived but released in large numbers
Contain lots of lysosomes
Engulf and digest pathogens
Usually die soon after digesting a pathogen
Dead neutrophils may collect in an area of infection to form pus
68
Process of engulf and digestion that neutrophils undergo
Neutrophil binds to opsonin attached to antigen of pathogen
Pathogen is engulfed by endocytosis to form a phagosome
Lysosomes fuse to the phagosome and release lytic enzymes into it
After digestion, the harmless products can be absorbed into the cell
69
Main points about macrophages
Larger cells produced in bone marrow
Travel in blood as monocytes (largest white blood cells with a kidney-shaped nucleus) before settling in body tissues
Monocytes found in lymph nodes where they mature into macrophages
Dendritic cells (type of macrophage) usually found in more peripheral tissues
Initiate specific responses to invading pathogens
Doesn’t fully digest after engulfing a pathogen: antigen from pathogen is saved and moved to special protein complex on cell surface so it becomes an antigen-presenting cell
70
Main points about antigen-presenting cells
Isolates antigen from pathogen and places it on plasma membrane so it can be recognised by other cells in the immune system
Special protein complex ensures antigen-presenting cell is not mistaken for a foreign cell and attacked by other phagocytes
Moves around the body to come into contact with T and B lymphocytes to activate the full immune response
Role is to increase chance of antigen coming into contact with lymphocytes
71
Key features of phagocytes
Receptor on plasma membrane
| Lysosomes (vesicles containing lytic enzymes)
72
Describe the specific immune response
The antigen can be detected by lymphocytes from an antigen-presenting cell, an infected somatic cell, or the pathogen in bodily fluids
B lymphocytes mature in the bone marrow
T lymphocytes mature in the thymus
Clonal selection (the selection of the correct lymphocytes with receptors complementary in shape to the antigens) occurs
Clonal expansion (more of these lymphocytes are needed to fight the pathogen so they divide by mitosis) occurs
73
T helper cells
Release cytokines with specific shapes which bind to complementary receptors on the plasma membrane of B lymphocytes, stimulating them to divide by mitosis and differentiate
Also stimulate macrophages to carry out more phagocytosis
74
T killer cells
Search for and kill infected host cells by secreting protease enzymes into them
75
T memory cells
Stay in the blood in case there is a second invasion by the same pathogen
Allow a faster secondary response because they recognise the antigen and can make clones and change to form new T cells more quickly than the primary response
76
T regulator cells
Shut down the immune response once the pathogen has been removed
77
Plasma cells
Produce and secrete antibodies which are complementary in shape to the antigen
78
B memory cells
Stay in the blood in case there is a second invasion by the same pathogen
Allow a faster secondary response because they recognise the antigen and can make clones and change to form new plasma cells and so antibodies are made more quickly than in the primary response
79
What are cytokines?
Hormone-like chemicals that stimulate differentiation and activity of macrophages, B cells and T cells
80
Another name for T lymphocytes in specific immune response?
Cell-mediated immune response
81
Another name for B lymphocytes in specific immune response?
Humoral response
82
Main points about antibodies
Immunoglobulins - complex proteins produced by plasma cells in the immune system
Made up of heavy and light polypeptide chains
Disulphide bridges hold polypeptides together
Hinge region allows flexibility so molecule can grip more than one antigen
Variable region is complementary in shape to antigen
83
Main points about agglutinins
‘Crosslink’ pathogens by binding an antigen on one pathogen with one binding site and then an antigen on another pathogen with its other binding site so the pathogens clump together
Agglutinated pathogens cant carry out some functions (e.g. entering host cells)
Readily engulfed by phagocytes
Particularly effective against viruses
