4.1 Communicable Diseases Flashcards
How does skin protect the body?
Acts as a barrier. Preventing pathogens entering the body.
What is the skin made of?
Outer layer is 90% Keratine. This dries and forms hard keratin.
What is sebum?
Oily substance on the skin that inhibits pathogen growth.
What is skin Flora?
The large amounts of skin cells out compete the pathogens.
What is a pathogen?
An organism that causes disease
What does a pathogen do?
Lives in and takes nutrients from a hosts body. Causing damage in the process.
What are the main types of pathogen?
Bacteria. Virus. Fungi. Protist.
What are communicable diseases?
Diseases that can be spread between organisms. Caused by one organism infecting another.
What is bacteria?
A prokaryotic unicellular organism that can cause disease. Not all bacteria cause disease though.
Why are bacteria bad for organisms?
Reproduce rapidly (some duplicate every 20 minutes). Produce toxins and waste products that damage the host.
What bacterial disease is found in plants?
Ring Rot
What is Ring Rot?
Wilting in lower leaves in Potato and tomato plants. Leaves roll inwards and leaf becomes a dull green. Vascular tissue then decays.
What is tuberculosis?
A Bacterial disease that usually attacks the lungs. Tissues and cells are killed. leading to respiratory issues.
How is tuberculosis spread?
Coughing and sneazing (droplet infection).
What is Bacterial Meningitis?
A bacterial disease that damages the membranes around the brain and spinal cord.
What are the symptoms of Bacterial Meningitis?
Fever. Stiff Neck. Headache. Nausea. Vomiting.
How is Bacterial Meningitis spread?
Coughing and sneezing (Droplet infection).
What bacterial diseases are found in animals?
Tuberculosis. Bacterial Meningitis.
How is Ring Rot spread?
Droplets and vectors
What is gram positive bacteria?
Bacteria that goes blue-purple when stained with gram stain.
Why does gram positive go this colour?
It goes blue-purple as it has a thick cell membrane.
What is gram negative bacteria?
Bacteria that goes red after gram staining.
What type of bacteria is most resistant?
Gram negative. More resistant to antibodies and drugs.
What is a virus?
A short section of RNA surrounded by proteins. All viruses are pathogens. Viruses carry out no life processes and are therefore not classified as living.
How do viruses cause infection?
They insert their RNA into the DNA of a host cell. This causes the cell to produce lots of viruses.
What are viruses that infect bacteria called?
Bacteriophages
What are the viral infections in animals?
Influenza. HIV/Aids.
What is Influenza?
A viral attack on the respiratory system.
What are the symptoms of Influenza?
Coughing. sore throat. runny nose. muscle pain and headaches.
How is Influenza spread?
Droplet infection.
What is HIV?
A viral disease that attacks the immune system and makes you more susceptible to other everyday diseases.
What does HIV stand for?
Human Immunodeficiency Virus
What is AIDS?
The name given to the life threatening diseases contracted due to the weakened immune system caused by HIV
What does AIDS stand for?
Acquired Immune Deficiency Syndrome
How is HIV/AIDS spread?
Direct physical contact
What is tobacco mosaic virus?
A viral disease that causes a mosaic of brown spots to appear on the leaves of plants. This prevents photosynthesis taking place. It usually doesn’t kill the plant, just stunts the growth.
How is tobacco mosaic virus spread?
Direct physical contact.
What viral disease is found in plants?
Tobacco mosaic virus
What is fungi?
Decaying matter. Eukaryotic cells but can be unicellular or multicellular.
How does fungi cause problems in plants?
It infects the vascular system and enters the leaves preventing photosynthesis. It also produces millions of spores that infect other organisms.
What is Ring Worm?
A fungal disease that commonly affects cattle but can be spread to humans. It causes a rash on the skin.
How is Ring worm spread?
Direct contact.
What is black sigatoka?
A fungle disease that affects bananas. Causes a reduction in leaf area and premature ripening. leading to a yeald loss (50%).
How is black sigatoka spread?
Direct contact and vectors.
What is athletes foot?
A fungal disease that affects the skin on the feet.
How is athletes foot spread?
Direct physical contact. Can spread to toe nails and hands.
What is a protist?
A eukaryotic cell that can be unicellular or multicellular.
How does a protist cause damage?
Usually causes harm when entering the host cell. It feeds on the host cell and grows.
What is maleria?
A protist disease that affects a person’s liver and blood. Within 24 hours can cause severe illness and potentially death!
What are the symptoms of maleria?
Fever. headache and chills.
How is maleria spread?
Vectors - female anthepeles mosquitos.
What is blight?
A protist disease that affects potato’s and tomatos. Causes collapse and decay.
How is blight transmitted?
Through contact of foliage and tubers of fruit in wet weather.
How do viruses cause damage?
Take over cellular metabolism and insert viral genetic material into the host cell. They reproduce rapidly and cause the cell to burst. destroying it.
How do protists cause damage?
Take over the cell. Digest the insides and use it as a medium to reproduce. It then bursts out the cell.
How does fungi damage cells?
Digest and destroy the cells. Some produce toxins.
How does bacteria cause damage to cells?
Produces toxins and waste products that are poisonous to cells. It often destroys the plasma membrane.
What factors affect disease transmission in animals?
Overcrowding.Culture and infistructure. Climate. Poor Waste Disposal. Compromised immune System. Poor Nutrition. Socioeconomic Factors.
What factors effect disease transmission in plants?
Overcrowding. Less resistant plant varients. Damp and warm conditions increase survival of pathogens. Climate Change. Poor Mineral Nutrition.
What is the difference between passive and active defences?
Passive defences are there all the time whereas active defences only show when the organism is under attack.
What are tarpenoids?
A chemical that produces a smell that pathogens don’t like. Some are antibacterial and antifungal.
What is bark?
A physical layer that provides a barrier to pathogens. Toxic and polymer structure prevents invasion. Can produce chemical defence called tannins.
What is callose?
A polly saccharide that blocks the seive tubes of plants to prevent the spread of pathogens.
What are phenols?
Chemicals that have antifungal and antiviral properties.
What are tannins?
Complex phenols that binds to the saliva in insects and digestive enzymes. Large tannin intake kills the insect, preventing the spread of pathogens.
What are alkaloids?
Chemicals with a bitter taste that prevents animals eating it. Also prevents protein synthesis in insects and larger animals.
What is cellulose?
A chemical that forms part of the cell wall in plants. It acts as a physical barrier to pathogens.
What is tylose?
A balloon like swelling in responce to injury. Swelling in the xylem prevents the spread of pathogens. Can contain chemicals that are toxic to pathogens.
What is stomatal closure?
Guard cells close the stomata to prevent pathogens from entering the leaf and causing infection.
What is lignin?
Thickening of the cell walls. It is a indigestible, waterproof chemical.
What are hydrologic enzymes?
Chemicals found between cells that break down bacteria and fungi.
What is necrosis?
Deliberate cell suicide. Cells around the pathogen purposefully die to restrict its access to water and nutrients, preventing spread.
What are waxy cuticles?
A waxy layer on the leaves that shed water. Pathogens sit in stagnant water so by sheding them it prevents infection.
How do lysosomes protect against pathogens?
Destroys pathogens in phagocytosis.
What are lysosomes?
An enzime found in tears urine and stomach acid.
What is ear wax?
Made of dead skin and fatty acids.
How does ear wax protect against pathogens?
Traps dust and microorganisms before they enter the body. Oily texture means they repell water and associated bacteria. Outward movement of wax prevents the pathogens from entering the body.
How does acid protect against pathogens?
Low PH causes pathogens to die so are no longer able to cause disease.
Where is acid found as a defence?
In the stomach and vagina.
Where is mucus made?
The goblet cells in the epithelial layer of the digestive and respiratory system.
How do mucus membranes protect against pathogens?
Mucus traps dust and foreign materials. Cilia move the mucus out of the airways and into the stomach acid. It also contains lysosomes.
How does coughing sneezing and vomiting protect against pathogens?
Causes the expell of pathogens from the body so they can no longer cause disease in the body. Vomiting is caused by stomach contractions.
How does inflamation protect against pathogens?
Causes a raised temperature along with swelling redness and pain. The raised temperature prevents pathogen reproduction. Releases a chemical called histamine.
How is inflammation brought about?
Specialised mast cells detect damaged cells.
What does histamine do?
Causes vasodilation of the capillary so they become leaky. White blood cells leak into the tissue fluid. More tissue fluid is produced causing swelling (oddema). It initiates a specific immune responce.
How does blood clotting occur?
Platelets release the enzime thrombokinase. Thrombokinase reacts with Ca²+ Ions to turn prothrombin into thrombin. Thrombin catalyses the reaction of causing the clot. Fibrin also pulls the side of the wound together to help the skin to recover. fibrinogen into fibrin. Fibrin binds to the wounds and traps platelets and erythrocytes
What is the chain of events found in blood clotting called?
An enzyme cascade
What is a fever?
An increased body temperature in responce to a disease.
How does a fever form part of the secondary non specific immune responce?
High temperatures mean that pathogens struggle to reproduce. The immune system works better at higher temperatures.
What are antigens?
Small proteins on the surface of all cell surfaces.
How do antigens form part of the secondary immune responce?
If the body thinks that an antigen is foreign (from outside the body) it triggers the specific responce.
What are opsonins?
Proteins that bind to pathogenic antigens.
How do opsonins help in the secondary non specific immune responce?
They help make the pathogen more ‘visible’ to phagocytes.
What is a neutrophil?
A type of white blood cell that engulfs pathogens and performs phagocytosis to destroy them. They are non specific.
What is the process of phagocytosis?
A phagocyte is attracted to a pathogen by the chemicals it releases. The phagocyte recognises the antigen as foreign. The phagocyte engulfs the pathogen placing it in a vacuole called a phagosome. A lysosome then attaches to the phagosome to form a phagolysosome. The enzymes in the phagolysosome then break down the pathogen. The brocken down pathogen is then removed from the cell by exocytosis.
What is a macrophage?
A type of white blood cell that is made from the maturation of monocytes in the bone marrow. They are part of the non specific immune responce but take longer to destroy pathogens than phagocytosis.
What do macrophages do?
Triggers a specific immune responce. The pathogen is engulfed and broken down. The pathogens antigens combine with the macrophages’ and form a major histocompatibility complex. The macrophages then presents the antigen on the cell surface to become an antigen presenting cell. It then travels to the lymph node to show the antigen and trigger a specific immune responce.
What are lymphocytes?
A type of white blood cell found in the blood and lymph nodes. Produced in the bone marrow and lymph nodes. They recognise antigens and initiate a specific immune responce.
What are the 2 different types of lymphocyte?
T lymphocytes and B lymphocytes.
What are the 4 T lymphocytes?
T Helper. T Killer. T Regulator. T Memory.
What does a T helper cell do?
Produces interleukins (a type of cytokine) that stimulates B cells and antibody production. Attracts other T cells and antibodys.
What is a cytokine?
A chemical messenger.
What do T killer cells do?
Attack and kill cells that present the foreign antigen including the host cells.
What do T regulator cells do?
Prevent an autoimmune disease by repressing the immune system after an infection. Stops T killer cells attacking too many own cells.
What do T memory cells do?
Stay in the blood and remember the antigen for that pathogen so it can be easily identified at a secondary infection so the responce can be quicker. They divide to form many T killer cells.
What are the different B cells?
Plasma Cells. B Effector Cells. B Memory Cells
What are plasma cells?
Cells that produce specific antibodies. They only last a few days but can produce 2000 antibodies a day. They are made in the bone marrow.
What are B effector cells?
B cells that divide to form plasma cell clones.
What are B memory cells?
B cells that remember the specific antibody for a pathogen. Can rapidly produce plasma cells that produce this in the case of a subsequent infection.
Where are T cells made?
The thymus.
Where are B cells made?
Bone marrow.
What is the process of clonal expansion?
B and T cells in the lymph nodes get activated by a pathogenic antigen matching their receptors. T cells reacts to antigen presenting cells. B cells react to the pathogen itself. These cells then reproduce rapidly to make many copies of themselves with the same receptors. The B cells produce plasma cells that produce the correct antibody and memory cells that remember the antibody. T cells go to the site of infection and fight it.
What does a responce curve look like?
Small peak for first infection. Never returns to 0. Rapid and high peak for second infection.
Why is the secondary responce different to the primary responce?
During the secondary responce the B cells know what antibody to make so do so quickly and produce lots of them. It is quicker as the antibody does not need to be identified.
What is aggulation?
When antibodys bind to pathogens and make them clump together. This makes the pathogens more easily engulfed by phagocytosis.
What is neutralisation?
Antibodies with antitoxin properties bind with toxins produced by pathogens to render them harmless.
What are antibodies?
Specialised glycoproteins called immunoglobulins. They are produced by plasma cells in responce to infection. They are specific and bind to one type of antigen - variable regions are complimentary to the antigen. They bind to antigens with the lock and key model.
What are the features of an antibody?
Heavy chain. Light Chain. Variable Region. Constant Region. Hinge Region. Disulphide Bridges. Antigen Binding Site.
How do Antibodys work?
They bind to the antigens on the pathogen and provide a binding site for phagocytosis. They are specific and prevent the pathogen from binding to a host cell.
What is a pandemic?
A disease spread on an international scale.
What is an epidemic?
A disease spread on a national scale.
What is in a vaccine?
Whole/live organisms - weaker than the actual disease. Harmless pathogens. Dead pathogens. Antigens only. Toxoid - harmless version of the toxin. A vaccine can contain one or many of these.
What is a vaccination?
The intentional exposure to pathogenic material in order to produce antibodys and memory cells. Memory cells bring about a rapid responce on second infection.
What is local vaccination?
Vaccinating only those most at risk of a disease. Could be the most likely to spread it or the most likely to be ill.
What is heard immunity?
When enough of the population is vaccinated against a disease (typically 80 - 85%) that it can’t spread around the population so therefore dies out.
What is Ring vaccination?
Only vaccinating people that may be exposed to the disease. Could be the family of the person who has it or a whole village. It is done in responce to the disease being identified rather than a precaution.
What are the 4 types of Influenza?
A. B. C. D.
What is B influenza?
Causes Seasonal illness.
What is A Influenza?
Influenza in birds and some mammals. In humans it can cause pandemics. Can cause seasonal illness.
What is C influenza?
Mild respiratory illness.
What is D Influenza?
Affects cattle and not thought to affect humans.
What are the types of immunity?
Natural. Artificial. Passive. Active.
What is natural immunity?
When you gain immunity as a result of normal infection and producing the memory cells.
What is artificial immunity?
Immunity from medical intervention such as a vacine to produce memory cells.
What is passive immunity?
When the antibodies are received from another source.
What is active immunity?
When you produce your own antibodies.
What ways are new drugs discovered?
Accident. Natural Medicine. Studying Wildlife. Modern Research. Personalised Medicine.
