Infection and response

What are pathogens

microorganisms which causes disease.

what are communicable diseases

Communicable diseases can spread between people.

How can pathogens spread?

Through direct contact, through the air, through water, via a vector (e.g. mosquito).

How do bacterial pathogens make us feel ill?

Bacteria may produce toxins that damage tissues and make us feel ill.

How do viral pathogens make us feel ill?

Viruses live and reproduce inside cells, bursting the cells, causing cell damage.

Type of pathogen causing measles

Viral disease.

Symptoms of measles

Fever and skin rash.

Type of pathogen causing HIV

Viral disease.

How is HIV spread?

Spread by sexual contact or exchange of body fluids eg sharing needles.

Symptoms of HIV

Attacks body's immune cells, can no longer deal with other infections leading to AIDS.

What does TMV stand for?

Tobacco mosaic virus.

Type of pathogen: TMV

Viral plant pathogen.

Symptoms of TMV

Mosaic pattern of discolouration on leaves which affects growth due to lack of photosynthesis.

Type of pathogen causing salmonella

Bacterial pathogen.

How is salmonella spread?

Caused by a bacteria ingested in food.

Symptoms of salmonella

Fever, abdominal cramps, vomiting and diarrhoea.

Type of pathogen causing gonorrhoea

Bacterial pathogen.

Symptoms of gonorrhoea

Yellow or green discharge from vagina or penis, pain when urinating.

What is a fungal disease which affects plants?

Rose black spot.

Symptoms of rose black spot

Purple or black spots on leaves, affects growth of plant as photosynthesis is reduced.

What is an example of a protist disease?

Malaria.

How is malaria spread?

Mosquito is a vector.

Symptoms of malaria

Fever can be fatal.

How can malaria be controlled?

Spread controlled by mosquito nets, stopping mosquitoes breeding etc.

Role of stomach acid in protecting against pathogens

Kills the bacteria in food.

Examples of non-specific defences in the human body

Skin - barrier; Nose - mucus to trap pathogens and hairs to move mucus; Trachea and bronchi - lined with mucus and cilia.

What is an antigen?

Proteins on the surface of pathogens.

Describe phagocytosis

when phagocytes engulf pathogens.

What is an antibody

Produced by white blood cells to attack pathogens. Complementary shape to the specific antigen of the pathogen. Can cause pathogens to burst or to clump together so they are easier to engulf.

What is an antitoxin

Produced by white blood cells to neutralise the effects of harmful toxins produced by bacterial pathogens.

What is a vaccine

A dead or inactive form of a pathogen which stimulates the white blood cells to produce antibodies.

How do you get immunity from vaccinations

When dead or inactive forms of a pathogen are injected into the blood, white blood cells produce antibodies. Memory cells remain in the blood. If the pathogen re-enters, white blood cells respond quickly to produce the correct antibodies, preventing infection.

What are antibiotics

Medicines which cure bacterial pathogens, such as penicillin.

What are the limitations of antibiotics

Cannot kill viral, fungal or protist pathogens.

When are painkillers used?

Used to treat the symptoms of a disease.

What are the limitations of painkillers

They DO NOT kill pathogens.

What is digitalis

The heart drug that originates from foxgloves.

What is aspirin

The painkiller that originates from willow.

What is penicillin

Antibiotic discovered by Alexander Fleming from the Penicillium mould.

Pre-clinical testing

Testing of drugs done in a lab using cells, tissues and live animals.

Stages of Clinical Testing

1. Trialled on healthy volunteers - testing for side effects;

2. Trialled on small group of patients - testing for dosage and effectiveness;

3. Trialled on large number of people - efficacy and side effects.

Double Blind Trial

Some patients are given a placebo, the others are given the drug. Neither researcher nor patients know who has a placebo.

Non-communicable disease

A disease which is not infectious and does not spread between people, such as diabetes or coronary heart disease.

What happens when you get a secondary infection

Usually less severe than primary infections because memory cells remain in the blood and can more produce antibodies faster.