Immune System- Abhay Flashcards
what are the main pathogens and give examples of diseases they cause
bacteria – tuberculosis (TB), bacterial meningitis, ring rot (potatoes, tomatoes)
virus – HIV/AIDS (human), influenza (animals), Tobacco Mosaic Virus (plants)
protoctista – malaria, potato/tomato late blight,
fungi – black sigatoka (bananas), ring worm (cattle), athlete’s foot (humans).
How to viruses damage host cells
Viruses insert their genetic material into the hosts cells DNA. They then use the host cell to reproduce.
How do Protoctists damage host cells
Protoctists take over cells and burst them open as a new generation emerge, they do not take over the DNA of the cell but just use the cell contents to reproduce.
How do fungi damage host cells
Fungi digest and destroy cells which they use to reproduce.
They also release toxins that break down cell membrane and inactivate enzymes
How do bacteria damage host cells
Most bacteria and some fungi produce toxins which break down the plasma membrane of the host cell and inactivates enzymes
What type of disease do bacteria cause and give a brief outline of what they do.
Ring Rot; damages plant tubers and leaves. A field cannot be used to grow plant for at least another 2 years.
Tuberculosis; damages and destroys lung tissue and suppresses immune system in animals.
Bacterial Meningitis; bacterial infection of the brain which can spread to the blood quickly causing blood positioning and potentially death
What type of disease do Viruses cause and give a brief outline of what they do
Tobacco Mosaic Virus- Damages leaves roots and stems stunting growth and leading to crop loss. There is currently no cure for it.
HIV/AIDs; Damages T-helper cells and gradually breaks down the whole immune system. No cure or vaccine for it yet.
Influenza Virus- Kill the ciliated epithelial cells of the airways leaving them open to secondary bacterial infection.
What type of disease do Protoctists cause and give a brief outline of what they do
Malaria (Plasmodium)- The female Anopheles mosquito is the vector for this. Malaria reproduces in the mosquito and is then transferred to a human when it feeds on their blood. It attacks red blood cells the liver and the brain.
Potato Blight- destroys leaves and tubers causing vast crop loss
What type of disease do fungi cause and give a brief outline of what they do.
Black Sigatoka; Fungus that invades and breaks down leaves causing them to turn black and preventing them from photosynthesising.
Ring Worm- A fungal diseases which attacks animals, it is not harmful but is unsightly and can cause irritation.
Athletes foot; grows on and digests the warm moist skin between toes. Anti-fungal cream is a cure.
What are the direct ways of transmission of a disease in ANIMALS
Touch- Kissing, intercourse, any skin to skin contact
From an animal bite,
open wound or sharing needles
Ingestion- Eating contaminated food e.g. undercooked chicken causes salmonella
What are the indirect way of transmission of a disease in ANIMALS
Inanimate Objects (fomites)- E.g. bedding, socks or clothes can transfer athlete foot.
Droplet infection- Droplets of saliva that leave your mouth when you talk cough or sneeze
Vectors- Usually animals e.g. Mosquitoes, flea rats, water can also be a vector.
What are factors that affect the transmission of a disease in ANIMALS
Overcrowded living or working conditions
Living in poorly ventilated housing
Poor diet
Compromised immune system- e.g. having HIV/AIDS or being on immunosuppressants
Socio-Economic Factors- Lack of access to doctors, low health care worker to patient ratio
What are the direct ways of transmission of a disease in PLANTS
When plants are in direct contact with each other e.g due to overcrowding
What are the indirect ways of transmission of a disease in PLANTS
Soil Contamination- Infected pathogens often leave spores on the ground e.g black Sigatoka spores which can infect the next crop that is grown there
Wind- Spores can be carried by the wind
Water- Raindrops can carry pathogen or irrigation system may be contaminated
Animals- Insects or animals can be vectors of pathogens
Humans- Can transfer pathogens from touch or fomites (clothing)
What are factors that increase transmission of a disease in plants
Plant varieties- That are susceptible to diseases
Monoculture- low genetic diversity means disease can spread rapidly as all crops are susceptible
Overcrowding- increases likelihood of contact
Warm conditions increase the chance of vectors surviving
Climate change- Increased wind and rainfall are vectors for pathogens
What is a pathogen
A disease causing microorganism
What is a vector
Something that carries a pathogen from one organism to another e.g (water/insects)
What is a communicable disease
A disease that can be passed on from one organism to another
What are the physical plant defences against pathogens
Cellulose cell walls- Acts as barrier to individual cells preventing pathogens from getting in
Callose- Is synthesised when a pathogen is detected, this is deposited in plasmodesmata selfing off the site of infection, calls barriers can also be lignified creating a thicker stronger barrier. Callose can also be deposited in sieve tube end walls to prevent the pathogen spreading via the phloem
Self sacrifice- Unlike animals plants do not heal damaged tissue they instead seal it off and sacrifice it as meristem is constantly dividing so organs can be replaced quickly.
What are the chemical defences plants use against pathogens
Producing Insect replants and insecticides e.g citronella or insect toxins
Producing antibiotics e.g. phenols
Producing anti fungal compounds e.g phenols or chitinases (compound which breaks down chitin cell wall of fungi)
Producing general toxin e.g cyanide which is poisonous to most organisms
What are the three main categories of non-specific immune response against a pathogen in Humans
Reflexes and barriers
Blood clotting & wound repair
Inflammation
What are the two physical barriers humans have to pathogens and what reflexes do humans have
The skin is a protective barrier found all around the body, it secretes sebum oils which inhibit the growth of pathogens, and contains many microorganisms which out-compete pathogens
Mucouse membranes, air ways and tracts in the body are often line with mucous membrane which secrets mucus to trap pathogens. Mucus contains phagocytes to digest pathogens and lysozymes which digest bacterial and fungal cell walls.
Expulsive reflexes e.g. coughing and sneezing expel pathogens out of our air ways
What is the function of platelets in blot clotting
Platelets secrete a molecule called thromboplastin which triggers a cascade of enzyme controlled events that results in the formation of a blood clot (fibrinogen forms fibrin which forms the blood clot)
The blood clot forms a tough protective scab which prevents the energy of pathogens
What is the function of serotonin in response to a wound or cut
Release of serotonin causes blood vessels to constrict reducing blood flow to the wound
What are the function of mast cells in the inflammatory response
Mast cells are activated in damaged tissues which release histamine and cytokines
What are the functions of histamines in the inflammatory response
Histamines make blood vessels dilate, increasing the blood flow to the pathogen making the area hotter which prevents pathogens from reproducing
Histamines make blood vessels more leaky/permeable causing blood plasma to leave blood vessels where it is called tissue fluid. Tissue fluid causes swelling
