Communicable Diseases, Prevention And The Immune System Flashcards
Define health
State of mental, physical and social wellbeing
Define disease
Departure from health due to malfunction of mind or body that cause symptoms
What is a pathogen
An infective organism which causes disease
What are the four types of pathogen
Bacteria
Fungi
Viruses
Protoctista
What do vectors do
Carry pathogens from one organism to another
Define degenerative disease
Results in gradual decline in bodily functions
Define infectious disease
Diseases which are transmitted by a pathogenic organism which invades the body
What does self inflicted disease mean
Disease caused by poor choices
Define deficiency disease
Diseases caused by poor diet
Define inherited disease
Disease caused by genetic faults passed on from parents
Define mental disease
Diseases affecting the mind
Define physical disease
Permanent or temporary damage to part of the body
What is a parasite
Organism that lives in or on a host taking nutrition and causes harm
What does a parasite take from the host
- nutrition
- warmth
- protection
How does bacteria affect the host
Damaging cells
Producing toxins
How fast does a bacteria do asexual reproduction
What is the process called
Every 20 minutes
Called binary fission
Bacteria is a prokaryote, what is the cell structure like
No nucleus
No membrane bound organelles
What are the two ways of classifying bacteria
By the shape ( rod shape, spherical, spiral…)
By the cell walls
How can you identify bacteria by the cell walls
Gram staining- identify the thickness of the peptidoglycan cell walls
This shows whether they are gram positive or gram negative
What do viruses make people ill
Invading cells Take over genetic machinery Make copies of viruses using cells ribosomes etc Host cell bursts Copies are released 🔁
What does a fungi do to make people ill
Live on the skin
Send out reproductive hyphae
These produce spores
And cause redness and irritation
They digest living cells and then destroy them
What type of organism are fungi
Eukaryotic
What is a saprophyte
Digest dead/decaying matter
How do fungi spread
They produce spores which reproduce
These can travel large distances ( ie in the wind )
What type of organism is protoctista
Single called Eukaryote
How do protoctista damage the host tissue directly
They digest and use the contents of a cell when they reproduce and eventually break open cells
What do toxins do
Break down the plasma membranes
Damage and inactivate enzymes
Prevent cell division
Name the three ways of direct transmission in animals
1) direct contact
2) inoculation (break into the skin)
3) ingestion
Name the three ways of indirect transmission in animals
1) formites ( bedding/ socks)
2) droplet infection
3) vectors
How can the probability of a catching a communicable disease
- overcrowded living places
- compromised immune system ( immunosuppressant drugs)
- poor disposal of waste
How are diseases directly transmitted in plants
-direct contact
How are plant diseases indirectly transmitted
- soil contamination
- vectors ( wind water animals)
What are some of the factors that affect the transmission of disease in plants
- over- crowding
- poor mineral nutrition
- damp, war conditions ( bacteria reproduce faster)
What are some of the plant barriers to pathogens
- tree bark
- waxy cuticle
- cellulose cell walls
- closing stomata
Define cell signalling
The coordination and communication between cells
Describe the process of cell signalling in plants in response to a pathogen
1) receptors in plant cells respond to molecules from pathogen made when plant cell is attacked
2) stimulates the release of signalling molecules
3) signalling molecules switch on genes in nucleus
4) this triggers a series of cellular responses:
- defensive chemicals
- defensive molecules to directly attack the pathogen
- callose and lignin made
Explain how callose is a plant defence
-When plants are infected by a pathogen they produce high levels of a polysaccharide called callose
-This is deposited between cell walls and cell surface membranes of cells next to infected cells
-they act as a BARRIER and prevent the pathogen entering cells around the site of infection
-Callose and lignin together make the barrier even thicker
-callose blocks sieve plates in the phloem sealing off the infected part
-deposited in the plasmodesmata to prevent spread
Acts as a matrix which antimicrobial compounds can be deposited in
Describe the structure of callose
Contains beta 1–3 and beta 1-4 glycosidic bonds
Name some chemical defences that plants produce
1) insect repellents- ie citronella
2) insecticides- caffeine is toxic to insects and fungi
3) antibacterial compounds- defensins
4) antifungal compounds- chitinases
5) anti oomycetes- glucanases
6) general toxins- cyanide
How do antibacterial compounds help a plant defend itself
Defensins- are plant proteins that disrupt bacterial/ fungal cell membranes
How do anti fugal compounds help plants defend themselves
Chitinases ( enzyme) hydrolyse chitin in fungal cell walls
How do anti oomycetes help plants defend themselves
Glucanases ( enzymes ) that break down glucans which are polymers found the cell walls of oomycetes
What is a oomycetes
A fungus like microorganism
How is cyanide toxic
Stops aerobic respiration
How is skin a primary non specific defence
- Covers the body and prevents the entry of pathogens
- Covered with a layer of healthy microorganisms which outcompete pathogens for space on the body surface
- Skin produces sebum
What is th importance of the skin producing sebum
An oily substance that prevents pathogen growth
It is anti microbial
How do mucous membranes act as a primary non specific defence
- body tracts including airways of gas exchange are lined with these mucous membranes
- these secrete mucus which traps microorganisms and contain lysozymes which destroy bacteria and fungal cell walls
- mucus contains phagocytes which remove remaining pathogens
What is the job of lysozymes
Destroy bacteria and fungal cell walls
What are some expulsion reflexes
What are they an example of
- coughing
- Sneezing
- vomiting
- diarrhoea
These are examples of primary non specific defences
Describe wound repair
Platelets come into contact with collagen In wall of the damaged blood vessel, they adhere and start secreting substances including:
- thromboplastin
- factor X
- serotonin
Forms a blood clot- this dries out forming a scab
Epidermal cells beneath the scab start to grow sealing the wound permanently
Collagen fibres are deposited to give new tissue strength
Once epidermis is normal, scab sloughs off and wound is healed 🤯
What does thromboplastin do
It’s an enzyme that triggered a cascade of reactions resulting in a blood clot
What does serotonin do
Makes smooth muscle in the wall of blood vessel contract
What does factor X do
It’s an enzyme that is dependent on the co factor vitamin K is catalyses the conversion of prothrombin into the enzyme thrombin ( does this by altering the tertiary structure)
Thrombin then catalyses the conversion of fibrinogen into insoluble fibrin fibres which then forms the blood clot
What are some of the characteristics of inflammation
Pain
Heat
Redness
Swelling
Explain the cell signalling response to inflammation
1) mast cells bind to pat often
2) mast cells release histamine in local area
3) histamines bind to localised cells receptors
4) histamines make muscle in walls of blood vessels dilate
5) this triggers increased blood flow to area which makes capillaries more permeable to phagocytes
What do cytokines do
Stimulate hypothalamus to reset internal temperature to above 37 degrees - stops pathogen from reproducing
Cytokines attract white blood cells to the site
What are the two types of phagocytes
Explain the difference
Neutrophils- released from bone marrow/ multi lobed nucleus
Macrophages- released from lymph nodes
How can u identify from a blood smear a…
Platelet RBC Neutrophil Monocyte Lymphocyte
Platelet- very small only fragments of cell RBC- no nucleus Neutrophils- multi lobed nucleus Monocyte- rounded nucleus Lymphocyte- massive nucleus
Describe the process of phagocytosis
1) phagocyte receptors bind to pathogens antigen
2) pathogen is identified by antigens
3) pathogen is engulfed by phagocytosis into phagosome
4) lysosome fuses with phagosome releasing digestive enzymes
5) pathogen is hydrolyse into amino acids or glucose
6) useful material is absorbed into cytoplasm
Name the digestive enzymes in a phagolysosome
Lysins
What is phagocytosis an example of
Endocytosis
What are opsonins
Chemicals that bind to pathogens and tag them
Making them easily recognised by phagocytes
Phagocytes have receptors on cell surface membranes that bind to common opsonins
Give an example of an opsonins
Antibodies
How often do bacteria reproduce
Every 20 minutes
What type of pathogen is tuberculosis
Bacteria
What does tuberculosis do
Damages the lungs and suppressed immune system
Can tuberculosis be cured
Can it be prevented
Yes by antibiotics
Yes can have a Vaccination
How is tuberculosis transmitted
1) bacteria is transmitted in droplets
2) bacteria is encased in tubercle
3) bacteria are then dormant
4) bacteria destroy alveoli
5) leads to fibrosis/ scaring
6) reduces diffusion through less surface area
What factors increase the transmission of TB
- weakened immune system
- overcrowding
- poor diet
- homeless
How is bacteria released into the air
Through coughing and sneezing this can spread the disease to other organisms
3 reasons why TB has not been eradicated
- Antibiotic resistance
- Vaccine is less than 100% effective
- Developing countries can not afford treatment
What type of pathogen causes meningitis
Bacteria
How does meningitis affect the organism
Affects the protective membranes on the surface of the brain called meninges
What are some of the other diseases that can be caused through meningitis
Can spread to the rest of the body causing blood poisoning and death
Can meningitis be cured
Yes if antibiotics are delivered early enough
Can
What type of pathogen causes ring rot
Bacterial
What damage does ring rot cause
Damage to leaves, tubers and fruits
Is there a cure for ring rot
No
What do viruses do
Invade cells Take over genetic machinery Make cells they have infected make viral copies Host cell bursts Copies released
What does HIV stand for
Human immunodeficiency virus
What does AIDs stand for
Acquired immunodeficiency syndrome
What does the HIV virus affect
T helper cells of the bodies immune system
What does HIV have that helps it join with a T cell
Receptors
Why is HIV difficult to prevent
No cure
No vaccine
High mutation rate
Cannot be treated with antibiotics
Why is HIV more common in Africa
Poverty
Less education on disease transmission
Promiscuity
More intravenous drug abuse
What type of pathogen is influenza
Viral
What does influenza affect
Ciliates epithelial cells of the respiratory system
These are killed and leads to secondary infection
what does a mutation cause
a change to the antigens on the surface of the cell
is there a vaccine for influenza
yes
it is given to vulneraable groups annually
how do new strains emerge
influenza virus mutates and the antigens on the cell surface change. means that memory cells are not as effective and no antibodies for new antigen are produced
increases difficulty in producing vaccines
what are we doing about the flu
national vaccinations for vulnerable groups: over 65yrs weak immune system infants pregnant women
explain the difference between epidemic and pandemix
epidemic- when a disease is located in a particular area
pandemic- when a disease is located across whole continents
what type of pathogen causes tobacco mosaic virus
virus
what does TMV cause
damage to leaves, flowers and fruit
causes a yellowing of leaves giving a mosaic pattern
stunts growth and reduces yield for farmers
describe protoctista
generally single celled
eukaryotes
enters cells and feeds on contents
what causes malaria
protoctista
the plasmodium
what is the vector for malaria
female anopheles mosquito
what does plasmodium infect
erythrocytes , liver cells and the brain
is there cure and vaccine for malaria
no and no
list 3 ways how we can deal with malaria
pesticide spray
sleep under nets
antimalarial drugs
name the process of transmission of the plasmodium parasite
1) female anopheles mosquito bites and releases saliva containing the plasmodium into the blood
2) plasmodium multiply in liver cells and are released back into the blood
3) gametes released into the blood
4) gametes taken into the female anopheles stomach on feeding
5) gametes fuse to form zygotes and then plasmodium in salivary glands
why is malaria such a problem
5 different species of plasmodium parasite
what is the cause of potato and tomato blight
protoctista ( the protoctist oomycete)
how does an oomycete differ to a fungus
cell wall made of cellulose in oomycete
what does the hyphae in potato and tomato blight do
penetrates host cell which causes destruction to leaves fruit and tubers
what does fungi send out, what does this cause?
reproductive hyphae which produce spores which can cause redness and irritation
what type of pathogen causes black sigatoka
fungi
what does black sigatoka do
causes black streaks in leaves and the fungus digests the leaves
what are some of the consequences of black sigatoka
reduces the plants ability to carry out photosynthesis
what is used to kill the fungus
fungicides
what type of pathogen causes ring worm
funghal
what does ring worm cause and what does this lead to
a scaly crusted rash that may appear as round, red patches on the skin
leads to itching and blister like lesions
how is ringworm cured
by using antifungal creams
what type of pathogen causes athletes foot
fungal
what is athletes foot a type of
ring worm
what does ring worm produce
enzymes that digest the skin
how is ring worm cured
using anti fungal creams
What type of pathogen causes athletes foot
Fungal
Where does the fungus in athletes foot live
In between the toes where it is moist and warm
What does the fungus in athletes foot produce
Enzymes that digest the skin
Define non self antigen
A glycoproteins on the surface of a pathogen which causes an immune response
Define self antigen
A glycoproteins on cell surface membrane of body cells
The immune system recognised these cells as self
How many polypeptides in an antibody
What bond holds them together
4 polypeptides ( 2 light and 2 heavy)
Disulphides bridges
What is the variable region specific to
That particular antibodies primary structure
What part of the antibody bonds to phagocytes
Constant region
What does the hinge region allow
Flexibility
What are the two functions of antibodies
Neutralisation and agglutination
What does neutralisation mean
Antibodies covering the pathogen binding sites prevent the pathogen from binding to a host cell and entering the cell
What does agglutination mean
A large antibody can bind many pathogens together
This makes them too large to enter a host celll
What are anti toxins
Antibodies that can also hind to toxins made by some pathogens this renders them harmless
What does complement cascade mean
Complement proteins in the blood interact with the bacterial cell surface membrane and form holes in it
What do the job of a macrophage
Engulf and digest pathogens in lymph nodes and present antigens on cell surface membrane
What is the job of a neutrophil
E gulf and digest pathogens in the blood around the body
Where do t- helper cells mature
In the thymus gland
Name the type of receptors on t helper cells
What do these do
CD4 receptors
They bind to the antigens presented on APCs
Once activated what do t helper cells release
What do they do
Interleukins
Stimulate the T cells to divide by mitosis
Interleukins also cause b-lymphocytes to divide by mitosis and stimulate the process of phagocytosis
What do cloned t. Cells divide into
T killer cells
T memory cells
What do t killer cells produce
Toxin hydrogen peroxide to kill infected cells
And perforin that makes holes in the cell surface membrane
What else do t memory cells do
They form the immunological memory
Live for a long time
Develop from cloned T cells as a result of cell mediated immunity
What do t regulator cells do
Controls and regulates the immune system
Stop immune system once a pathogen has been eliminated
Prevents autoimmune disease- when immune system doesn’t recognise self antigens correctly it starts to destroy its own cells/ tissues
What do the t helper cells do
Activated b lymphocytes at the start of the humoral response
Made in cell mediated immunity
Where do b lymphocytes mature
In the bone marrow
What do b lymphocytes do
Divide by mitosis to form cloned B cells that make lots of B memory cells and plasma cells
What are the 4 key communication methods
Identification- antigen acts as a ID indicating whether it is foreign
Presentation- antigens presented on membranes
Distress signals- pathogen May be placed into the cell surface membrane which tells the t killer lymphocytes to destroy it
Instructions- cytokines released by cells allow communication and coordination between cells
What are the two processes interleukins stimulate
B cells to divide
Development of t killer cells
Phagocytosis
What is the job of an interferon
Stimulates t killer cells and inhibits virus replication
What is the job of plasma cells
What causes this
Produce antibodies
Cytokines
Describe the shape of the receptors for cytokines on b lymphocytes
Complementary
Activated the mitosis of B lymphocytes
What type of lymphocyte is involved with cell mediated immunity
T lymphocytes
Describe the process of cells mediated immunity
1) macrophages engulf and digest pathogens
2) macrophages process antigens from pathogens and present them on their surface
3) some of the t helper cells have receptors that fit the antigen. They become activated (CLONAL SELECTION)
4) cloned T cells formed by (CLONAL EXPANSION)
5) develop into t memory cells or t killer cells
Produce interleukins which stimulates B cells to divide
Describe the process of humoral immunity
1) antibody on surface of a B cell binds to antigens
B cells processes antigens and presents them on the surface of their cell
2) activated t helper cell bunds to antigens on B cell APC ( CLONAL SELECTION)
3) interleukins produced by activated t helper cell activate B cell
4) activated B cells divide by osmosis (CLONAL EXPANSION)
5) clone cells form plasma or memory cells
6) plasma cells produce antibodies
Define CLONAL selection
When a T cell or a B cell has a matching receptor to the antigen
What is CLONAL expansion
When the selected T cell or B cell divided by mitosis to make many clones
What type of pathogen does the humoral response involve
B lymphocytes
What does the humoral system produce
Antibodies
How do each of the following help the fight of pathogens
Macrophages
Plasma cell
Killer T Cells
Macrophages Engulf and digest pathogens
Plasma cells produce antibodies
Killer T cells produce h-peroxide and preforin
What response is used for
Intracellular
Extra cellular
Intracellular - cell mediated immunity
Extracellular- humoral mediated immunity
Define immunity
The ability of an organism to resist a particular infection or toxin by the action of specific antibodies or sensitised white blood cells
Describe natural active immunity
When you meet a pathogen for the first time you produce T + B memory cells
When u meet these again your immune system recognises antigens
Large quantities of the appropriate antibody are made very quickly
Describe natural passive immunity
Antibodies cross the placenta when the developing foetus is in the uterus
Also passed on in breast milk
Describe artificial passive immunity
Antibodies are made in one organism, extracted and injected into another organism
Treatment is instant
Describe artificial active immunity
Vaccination
Small amounts are injected into the blood
Triggers primary immune response
Memory cells are made
How does a vaccination work
1) contain antigens in vaccine
2) usually injected ( if taken orally could be broken down by enzymes)
3) cause antibody production and memory cells
4) makes u less likely to suffer
Define epidemic
Where disease is located in a particular area
Define pandemic
Where a disease is located across continents
What happens in an autoimmune disease
The immune system stops recognising cells of body as being ‘self’ so attacks its own healthy tissue
Why are some of the reasons an autoimmune disease may develop
There is a genetic link
Immune system responds abnormally to a mild pathogen
T regulator cells are not working right
Name three examples of autoimmune diseases
Type 1 diabetes
Rheumatoid arthritis
Lupus
What are some of the ways new drugs can be developed
Plants, chemicals, microorganisms
Scientists also use computer programmes to design drugs
Genetic engineering- some mammals have been re engineered to produce drug in their milk
What is pharmacogenetics
Where scientists will look at the patients genome and consider it for any weaknesses
Scientists will look for specific cancer causing genes and treat it with specific drugs
What are humans doing that is damaging our potential access to new drugs
Deforestation and climate change- species going extinct
Name the 5 ways how antibiotics work
1) disrupt the cell wall
2) disrupt membranes
3) inhibit protein synthesis
4) inhibit dna/rna processes
5) disrupt metabolism
How do animals spread antibiotic resistance
They are fed antibiotics- develop resistance in there gut
The meat that is not taken from them may have this resistance on it and when not handled properly bacteria can spread to humans
How can a person develop antibiotic resistance
Are given antibiotics
Develop resistance in there gut
Spread it to the local comminuty
Or go to hospitals and spread it to patients there
Name three causes of antibiotic resistance
1) over prescribing antibiotics
2) lack of hygiene
3) lack of new antibiotics developed
