B6.2 - Communicable Disease Flashcards
What is health?
The physical and mental well-being of an organism which is free from disease or injury
What is disease?
Disorders that affect all or part of an organism
What does contagious mean?
Diseases that can be spread from organism to organism. Caused by a pathogen
What is a pathogen?
A microorganism that can enter the body and pass on disease
What is bacteria?
A single celled microorganism that can reproduce asexually and cause disease
What is a communicable disease?
Pathogens cause these
-diseases that can pass by contact from organism to organism
What is a non communicable disease?
Diseases that don’t pass from organism to organism via contact
-these come with risk factor
What is a risk factor?
Increases the chance of getting a disease but does not cause it
What are the four main types of pathogens?
Fungi
Bacteria
Protozoa
Viruses
What is fungi?
1) They are a Kingdom of organisms which exist as long tubes of cells with many nuclei.
2) They reproduce using spores which spread and grow into new fungi
3) They grow in wet and humid conditions
What is Bacteria?
1) A single celled organism without nucleus which reproduce rapidly to cause disease
2) They cause symptoms by producing toxins that damage cells and tissues
What is the incubation period?
The time from first infected and when symptoms start to arise. During the time toxins build up by the bacteria.
What are viruses?
- smallest of the pathogens
1) Are not cells. Consist of piece of genetic material inside a protein coat
2) They replicate themselves inside the cells of the organisms. Then burst releasing the viruses
What are protozea?
Single celled organisms with a nucleus
Ways pathogen can enter the body?
1) Drinking contaminated water or eating contaminated food
2) Breathing or swallowed in
3) Insects carrying illnesses
4) Through open wounds or cuts
5) Through sexual activity
2 examples of bacteria pathogen infections? CAUSES AND SYMPTOMS AND TREATMENTS
Gonorrhea Caused -> Sexually transmitted SYMPTOMS -thick yellow or green discharge from vagina or penis -Pain while urinating TREATMENT -Antibiotics (penicillin) -Use barrier method contraception like condom
Salmonella Caused -> Eating contaminated food (food poisoning) SYMPTOMS -fever -abdominal cramps -Vomiting -Diarrhoea TREATMENT -Vaccinating chickens against disease -Cook in hygienic place
What are examples of viral pathogen infections ? CAUSES AND SYMPTOMS AND TREATMENTS
HIV
Caused -> Sexually transmitted
SYMPTOMS
-Attack body immune system so it can’t fight against other infections
TREATMENT
-Antiretroviral drugs which don’t completely cure but reduces symptoms
Measles Caused -> inhaling droplets (cough and sneezes) SYMPTOMS -Fever -red rash over skin TREATMENT -Effective vaccine
TMV - Tobacco mosaic virus Caused -> enters through break in plants SYMPTOMS -it affects growth -reduces photosynthesis rate -mottling (patches and colour regulations) TREATMENT -Removing infected material -sterilizing the roots with heat
What is a passive defence?
- an adaptation to prevent pathogen entry or growth which is always present (constant defence)
What is a active defence?
A defence triggered as a direct response
How does skin defend against pathogens?
1) Strong layer acts as barrier from entry of pathogens
2) Sebaceous glands produce antimicrobial oils
How does the eye defend against pathogens?
1) Eyelashes reduce amount of things getting into eye
2) Tears from eyes are anti-microbial, killing pathogens
3) Eyebrows redirect liquids running into eye
How does the stomach defend against pathogens?
Contains hydrochloric acid - strong acid that kills certain bacteria
How does the lung/ airways defend against pathogens?
1) Have cilia (tiny hair like structures) and goblet cells (produces mucus)
2) Goblet cell produce mucus which traps microorganisms
3) Cilia uses energy from respiration to constantly move pushing the mucus up the throat
3) Mucus is swallowed to stomach where microorganisms are killed by HCL acid
How does the nose defend against pathogens?
1) Internal hairs acts as physical barrier against pathogens
2) Nose produces mucus to trap microorganisms before entering lungs
How does platelets defend against pathogens?
- Platelets from process to form clots (stopping pathogens from getting in)
1) When platelets exposed to oxygen in air they react to stimulate fibrin production forming a mesh around wounds
2) The mesh traps the red blood cells causing them to dry forming scabs
What is the 3 layers in blood from heaviest to lightest?
HEAVIEST
1) Red blood cells: packed with hemoglobin protein
2) White blood cells and platelet layer
3) Plasma: dissolved in is…
- Urea
- Carbon dioxide
- ions
- Glucose
- hormones
- amino acids
- antibodies
What is the first line of defence against pathogens?
Passive physical barriers
-They are constantly on to keep pathogens out (like skin)
What line of defences are there if pathogen enters past first line for defence and examples?
- Active, non specific response (response when pathogen detected and the same defence for every pathogen)
EXAMPLES: Phagocytes
- Active, specific response (response when pathogen detected but specific to different types of pathogens)
EXAMPLE: lymphocytes
What do Phagocytes look like?
- Lobed nucleus
- Larger cell than lymphocytes
What do Lymphocytes look like?
-Large nucleus
What 2 proteins do lymphocytes produce to fight off pathogens?
- Antibodies
2. Antitoxins
What do antibodies do?
They bind to antigens and:
1) They bind pathogens together so they can’t work effectively
2) They can kill pathogens themselves
3) They can ‘label’ pathogen for other cells in the immune system
What do antitoxins do?
They neutralise toxins stopping them from becoming toxic
What are the two regions of an antibody?
VARIABLE: (top of Y shaped antibody)
They change so they can be a complementary shape to antigens to bind to it
CONSTANT: (Bottom of Y shaped antibody) They are constant so they can always be recognised by other immune system cells (like Phagocytes)
Steps to Phagocytosis:
1) Phagocyte is attracted to pathogen due to bound antibodies on pathogen’s antigens
2) When reached pathogen it engulf it into a phagosome
3) Lysosome fuses with phagosome releasing hydrolytic enzymes into it
4) These enzymes break down the pathogen
What are memory cells?
- They stay in the blood for long periods of time and memorise antibodies required to bind to a specific antigen.
- They can produce rapid and large amounts of antibodies if that specific antigen on a pathogen is detected again.
Definition of a vaccination?
They allow immunity to a specific disease without the person becoming infected themselves
How do vaccinations work?
1) A vaccine contains a weak or dead version of the pathogen which is injected into the person. The pathogen is too weak to reproduce therefore person doesn’t become infected.
2) The immune system however is stimulated and lymphocytes are produced to produce specialised antibodies with complementary shape to the pathogen’s antigens to fight off pathogen with ease as it is weak
3) Memory cells memories antibody required to kill the specific pathogen if the same type of pathogen (which is able to cause a disease) enters the body again. If it does enter the body, memory cells will divide and produce a vast amount of antibodies
4) This is why body can fight off pathogens if person contracts the disease
Graph for concentration of antibodies against time when pathogens are detected?
TRY DRAW THE GRAPH:
Y AXIS = Concentration of antibodies
X AXIS = time
1) Graph doesn’t rise immediately as it takes some time for immune system to produce lymphocytes required to produce antibodies
2) As lymphocytes produced they produce antibodies therefore concentration increases until primary immune response (when immune system comes into contact with pathogen for first time)
3) The concentration of antibodies decrease after but not to zero as the body now has memory cells, level of antibodies decrease as they are not needed
4) If there is a second exposure to the same pathogen the graph shoots up rapidly as body can produces huge amount if antibodies rapidly (due to memory cells)
What is herd immunity:
- Caused by vaccinations
- > When population has low cases but people are not immune (not vaccinated) disease will spread rapidly as transmission is high
- > When a couple people vaccinated less people will have disease overall as it reduces transmission from person to person
- > Population with herd immunity (majority of people vaccinated), virus cannot spread from person to person. Low cases
What are the two ways to get immune to a disease?
- Getting vaccinated
- Catching and letting body fight off disease
What are monoclonal antibodies?
They are antibodies produced in the laboratory from a cell called a hybridoma cell (made of a fusion of a myeloma cell(cancer cell) and a lymphocyte) which bind to antigens on pathogens.
Why do we use monoclonal antibodies?
They help neutralise pathogens from working and are injected in the body to search for the target pathogen cells
How do we create monoclonal antibodies?
1) Genetically modified mice are injected with required antigens
2) Their immune system will stimulate and lymphocytes will be produced to fight off antigens
3) Take out and collect the lymphocytes from spleen of mouse
4) The lymphocytes cannot survive outside body so they are fused with myeloma cells from bone marrow which reproduce indefinitely. These fused cells are called hybridoma cells (have properties of both myeloma and lymphocytes)
5) The hybridoma cells go through mitosis and reproduce to form clones
6) Each clone produces the required antibodies which are collected called monoclonal antibodies
7) These can be injected into person to help fight or stop efficiency of pathogen.
What are the properties of hybridoma cells?
1) They can reproduce indefinitely and can survive outside body (due to cancer cells/ myeloma)
2) They can produce antibodies (due to lymphocytes)
How can monoclonal antibodies be used in pregnancy test?
1) Pregnant women produce the hormone hCG and pregnancy test detect this hormone
2) The bit of pregnancy stick which is urinated on has some antibodies to the hCG hormone with blue dye molecules attached
3) The test strip (which turns blue if pregnant) has some more antibodies to the hCG hormone stuck to it
4) IF PREGNANT:
- hCG hormone binds to antibodies on the blue dry molecule
- The urine moves up the stick carrying hormone and the dye molecules
- The dye molecules and hormone bind to the antibodies on the strip
- The blue dye molecules get stuck on strip turning it blue
5) NON PREGNANT
- the urine still moves up stick carrying blue dye molecules but there is nothing to stick the blue dye onto the strip, it doesn’t go blue
How can monoclonal antibodies be used in testing for certain diseases?
1) some monoclonal antibodies act as markers
2) Cancer cells have specific antigens which bind to specific monoclonal antibodies
3) Monoclonal antibodies with radioactive tags can be produced which bind to cancer cells. These antibodies can be detected by scanning
How can monoclonal antibodies be used in treatment?
1) Monoclonal antibodies bind to specific pathogens due to their antigens and can kill them or stop them working effectively
2) Could also carry drugs directly to cancer cells. Increasing effectivity. Also minimize damage to surrounding tissues
What are the types of drugs?
Painkillers: They don’t kill pathogens but instead relieve pain by blocking synapses and neurotransmitters allowing for easier resting
Antibiotics: Chemicals that selectively kill bacteria or stop them from reproducing without killing body cells
Antiviral: Drugs that prevent viruses from reproducing
How does virus spread and cause disease?
They intrude into the cells of the organism and reproduce. They soon cause the cell to burst and spread.
What are the steps to drug testing?
Step 1: Testing human cells
- Human cells grown artificially in lab
- Put sample of drug on the cell and look through microscope
- monitor for any negative change in cells
Step 2: Testing on animals
- If pass step 1 move to step 2
- inject animal with drug and look for negative side effects
Step 3: Testing on humans
- First test small group of healthy people to see for side effects on people with strong immune system
- The test on group of people with condition to see if the drug actually works
- Finally test on large scale of people with condition to conclude
What type of clinical testing trial do we use in step 3 of drug testing? How does it work?
Double blind trial
1) Distribute some real and fake drugs to different doctors spontaneously so doctors and patients don’t know if the drug is real or fake (this eliminates the placebo effect: the patient subconsciously believing they are getting better but they aren’t)
2) Ask doctor to monitor patient, the results should give an indication of if it works
What 3 things should a new drug be?
Efficient: Actually be able to prevent disease well
Safe: not too toxic or produce undesirable side effects
Sustainable: Be able to store drug for long period
What type of pathogen causes Malaria?
Protozoa/ Protists
What is an epidemic , pandemic, endemic?
Epidemic: The rapid spread of a disease to many people quickly
Pandemic: The rapid spread of a disease globally
Endemic: A disease that is always present and spreading but is controlled and in low numbers
What is the vector that spreads malaria?
Female Anopheles Mosquito
Why can only female mosquitoes spread malaria?
Males only feed on nectar while females fed on blood to obtain nutrients required for their eggs
Why do people catch malaria
Caused by getting bitten by a female anopheles mosquito carrying malaria infected blood
Who are the people most at risk from malaria?
Infants,
Children under 5
People with HIV /AIDS
Pregnant women
Where are mosquitos found? Why?
- In tropical climates
1) Life span of a mosquito is linked by temperature and humidity
2) Requires water for breeding
3) Mosquitoes reproduce more in hot and wet climates
How can malaria be controlled?
- Spraying pools with insecticides
- Spraying pools with oil preventing larvae form breathing
- Draining pools
- Use mosquito nets
- Drugs prescribed for protists
Symptoms of malaria?
-Shivering
-fever
-Joint pain
-Vomiting
Shivering
-Anemia
What is the pathogen responsible for malaria called?
Plasmodium
What is the lifecycle of malaria?
1) When a person is bitten by a infected mosquito, Plasmodium enters the body and travels to the liver where it reproduces before entering red blood cells
2) The red blood cells burst releasing the plasmodium. They also release the poisons the plasmodium had produce which cause symptoms
3) When the female anopheles mosquito bites the infected person they pick up the plasmodium pathogen by their mouth parts
4) When the pathogen bites another person they become infected and the cycle of malaria continues.
What causes plant diseases?
Bacteria Fungi Virus Insects Mineral deficiencies
What is nitrates used for in plants?
To produce amino acids for growth
What is magnesium used for in plants?
To produce Chlorophyll for photosynthesis
What is phosphates used for in plants?
To produce DNA and cell membranes required for respiration and photosynthesis
What is potassium used for in plants?
Helps enzymes function properly in respiration and photosynthesis
3 types of plant defenses + definitions
Physical defense: Always present and prevent pathogen from entering
Mechanical defenses: Physical additions that deter organisms eating the plant
Chemical defenses: Plant releasing chemicals to deter the organism from consuming or infecting it
Examples of physical defenses in plants?
Bark: layer of dead cells preventing pests from reaching living cells inside
Leaves: Tough waxy cuticles prevent pathogen entering to epidermis
Cell walls: Makes it harder for pathogens to enter cells
Examples of Mechanical defenses in plants?
- Some plants have thorns or hairs
- Some leaves release chemicals that release water from vacuole causing plants to droop and become less visible
- Some plants mimic other organism
Examples of chemical defenses in plants?
- Make chemicals that are unpleasant to consume
- Make toxic chemicals to harm organism
- Produce antimicrobial chemicals to prevent infection
What is:
Antiseptics
Disinfectants
Antiseptics: Can be used to stop bacteria spreading and growing
Disinfectants: Non specific - works by killing microbes every disinfectant has different concentrations - it has to be strong enough to kill pathogens
What is the definition for antiseptic techniques?
Allows us to reduce an experiment being contaminated by unwanted bacteria
How do we reproduce microbes?
Before and during experiment
Before:
1) Close windows and doors to minimize draft
2) Sterilize workbench with a 70% alcohol solution
3) Place Bunsen burning in center to create a constant updraft of air, drawing away unwanted microbes settling on equipment
During
1) Put inoculating loop at a downwards angle through Bunsen burner until it turns red
2) Petri dish containing Agar Jelly (it contains the necessary nutrient for bacteria to grow)
3) Transfer bacterial cell onto the Agar Jelly using inoculating loop (which has been dipped in bacterial substance) by removing the lid slightly away from body making sire the agar jelly isn’t dented.
4) Tape the petri dish and place upside down to prevent condensation
5) Place petri dish in incubator for bacteria to produce at the best condition
How do we test for the strength of disinfectants / antimicrobial substances?
1) Divide petri dish into 4 pieces using a marker
2) Dip 3 different paper discs into different disinfectants and dip 1 into water
3) Place the paper disc into different quadrants on the Agar jelly
4) Using sticky tape secure petri dish and incubate at 27 degrees
5) Zones of inhibitions should form around paper disc
What is the zone of inhibition / clear zone?
+
What does area of inhibition tell us about disinfectant strength?
area on agar plate around the paper discs where the growth of bacterial population has been prevented due to an antimicrobial substance.
Large area: substance has strong antimicrobial property
Small area: substance has weak antimicrobial properties
What is Binary fission?
Prokaryotic bacteria reproducing asexually doubling every few minutes
What is the graph for Bacterial Growth Curve?
X axis: Time
Y axis: Population of bacteria
Lag phase: no increase in population immediate - bacteria has to replicate DNA during this time
Exponential phase: Bacteria grows rapidly - as bacteria is doubling every few minutes
Stationary phase: Bacteria multiplying = Bacteria dying out. Resources are used up and toxic waste products are produced killing some bacteria
Death phase: Bacteria begins dying out
What example of fungal pathogen infection? CAUSES AND SYMPTOMS AND TREATMENTS
-Caused by Diplocarpon rosae
- Reduce plant vigor: How they grow and how healthy they look
- From spring causes markings on leaves which are permanent
Cut infected part off
