B3 - Infection and Response Flashcards
Methods of direct transmission?
- Direct contact
- Sexual contact
- Placental transfer
Methods of indirect transmission?
- Vectors
- Droplet infection
- Waterborne and food
Methods of prevention?
- Destroying vectors
- Simple hygiene methods
- Isolation and vaccines
How do viruses reproduce?
- They insert their genetic material into host cells and creating new protein capsules to build new viral particles
- Then the host cell will burst open releasing all the viral particles
Symptoms of measles?
- Fever
- Red rash
How is measles spread?
Inhalation of droplets from coughs and sneezes
Prevention of measles?
Vaccination programme in the UK
Treatment of measles?
- No treatment
- Isolation
Symptoms of HIV?
- Flu-like illness
- Can attack the immune system
- Can stay hidden for many years until it becomes AIDS
How is HIV spread?
- Direct sexual contact
- Exchange of bodily fluids
- From mother to child in birth or breast milk
Treatment for HIV?
- No treatment
- Antiretroviral drugs can slow the disease
Symptoms of Tobacco mosaic virus?
- Mosaic discolouration on the leaves
- Stunted growth
Spread of tobacco mosaic virus?
- Plants in direct contact with other plants
- Virus can stay in the soil for 50 years
Treatment of tobacco mosaic virus?
- No treatment
- TMV resistant crops
Good field hygiene
How do bacteria cause illness?
They produce toxins that cause damage to cells and tissues
Optimum conditions for bacteria?
- Warmth
- Moisture
- Supply of nutrients
Symptoms of salmonella?
- Fever
- Abdominal cramps
- Vomiting
- Diarrhoea
How is salmonella spread?
- Contaminated food
Salmonella prevention?
- Chickens are vaccinated
- Proper kitchen hygiene
- Washing surfaces and hands
Symptoms of gonorrhoea?
- Yellow or green discharge
- Can cause infertility, ectopic pregnancies and pelvic pain
Spread of gonorrhoea?
Unprotected sexual contact
Prevention of gonorrhoea?
Barrier contraception
Treatment of gonorrhoea?
Antibiotics
Chemical and physical human defences?
- Hair and mucus in nose
- Mucus and cilia in the trachea
- Acid in the stomach
- Skin ( sebum )
Main component of the immune system?
White blood cells
In depth, how does phagocytosis work?
- Phagocytes engulf and digest pathogens by surrounding the pathogen and releasing enzymes to digest and destroy it
How are antibodies produced?
Antibodies which have a complementary shape to antigens on a pathogen are produced, this can take some time which is why you feel unwell for a while
What are memory cells?
Lymphocytes that remain in the body after the infection, they will then be able to make those antibodies quicker if the infection occurs again.
How are antitoxins produced?
Lymphocytes produce specific antibodies called antitoxins which neutralise the toxins
Advantages of vaccinations?
- Diseases that were once common are now rare
- Epidemics can be prevented
Disadvantages of vaccinations?
- The vaccine doesn’t always give immunity
- There can be side effects to vaccinations
How do vaccines work?
- Harmless pathogen injected
- Antigens trigger an immune response
- Lymphocytes produce complementary antibodies which are released
- Memory cells are produced so they know what to do if re-infection occurs
What are the two types of immunity?
- Active immunity
- Passive immunity
What is active immunity?
Immunity that comes from the body creating antibodies from exposure by the disease of vaccination
What is passive immunity?
Immunity that comes from antibodies given by another organism such as breast milk
What do all new drugs need to be tested for?
- Toxicity
- Efficacy
- Dose
Three stages of drug testing?
- Preclinical
- Whole organism
- Clinical
What happens during preclinical testing?
- The drug is tested on cells in a lab
- Computer models may also be used to simulate how the drug might work
What is tested during preclinical testing?
Efficacy and toxicity
What happens during whole organism testing?
- The drug is tested on animals to see how the effect works
- In the UK this must be on two different animals
What is tested during organism testing?
Efficacy, toxicity and dosage
What happens during the clinical trials?
- A low dose is tested on human volunteers to make sure it is safe (toxicity)
- It is tested on patients with the condition, some with placebo in a double blind study, the lowest effective dose is tested
How are monoclonal antibodies produced?
- A mouse is injected with the antigens of the disease
- The mouse produces lymphocytes with the specific antibodies for the disease
- The lymphocyte is fused with a tumour cell to form a hybridoma
- The hybridoma cell is cloned, resulting in many divisions to make high quantities of the same antibodies
Uses of monoclonal antibodies?
- Pregnancy tests
- In labs to measure hormone levels or detect pathogens
- To locate specific molecules in a cell or tissue with fluorescent dye
- Tp treat disease such as cancer
How do pregnancy tests work?
- Sample pad is dipped in urine
- Reaction zone contains HCG-specific antibodies that are mobile and bound to blue dye
- Result window contains non-mobile HCG-specific antibodies
- Control window contains immobilised antibodies complementary to the reaction zone antibodies
How do monoclonal antibodies work to diagnose disease?
They can bind to the antigens on cancer or pathogens because the antibodies will be specific to what they are looking for
How are monoclonal antibodies used to measuring and monitoring?
They can be used to detect the quantity of chemicals or pathogens such as drug testing in athletes
How are monoclonal antibodies used in research?
Monoclonal antibodies bound with a dye can detect specific molecules in a cell or tissue
How are monoclonal antibodies used for treating disease?
To treat cancer:
- Trigger immune cells
- Block receptors to stop growth and division
- Carry toxic drugs or radioactive substances
Advantages of monoclonal antibodies?
- Only bind to diseased cells so don’t affect healthy ones
- Highly specific so can be used for many things
- Hoped to be a cheaper procedure
Disadvantages of monoclonal antibodies?
- More side effects
- Expensive at the moment
- More difficult than expected
What are monoclonal antibodies?
Antibodies produced from a single clone of cells that are specific to one binding site on one protein antigen
What are non-specific defences?
General physical and chemical barriers that defend the body against pathogens
What is vaccination?
The process of introducing small quantities of dead or inactive forms of pathogens into the body to simulate an immune response
