Infection and response

Describe salmonella: how it spreads, symptoms, and treatment. (Bacterial)

• Spread: contaminated food (e.g. undercooked poultry / eggs)

• Symptoms: fever, stomach cramps, diarrhoea, vomiting

• Effect: infects digestive system

• Treatment: antibiotics (if severe), rehydration

Describe gonorrhoea: how it spreads, symptoms, and treatment/prevention. (Bacterial)

• Spread: sexual contact / bodily fluids

• Symptoms: thick yellow/green discharge, pain when urinating

• Effect: infects reproductive system

• Treatment: antibiotics

• Prevention: condoms

Describe rose black spot: how it spreads and its effects on plants, plus treatment. (Fungal)

• Spread: fungal spores (wind / water)

• Symptoms: purple/black spots on leaves, leaf drop

• Effect: reduces photosynthesis → weak plant growth

• Treatment: fungicides, remove infected leaves

Describe athlete’s foot: how it spreads, symptoms, and treatment. (Fungal)

• Spread: direct contact or shared damp surfaces

• Symptoms: red, itchy skin between toes

• Effect: skin infection

• Treatment: antifungal creams

Describe malaria: how it is spread, its symptoms/effects, and prevention/treatment. (Protist)

• Spread: female mosquito (vector)

• Symptoms: recurring fever, chills, sweating

• Effect: infects red blood cells → anaemia

• Treatment: antimalarial drugs

• Prevention: mosquito nets, insect repellent

Describe measles: how it spreads, symptoms, and prevention. (Viral)

• Spread: droplets from coughs/sneezes

• Symptoms: fever, red rash

• Effect: respiratory infection

• Prevention: vaccination (MMR)

• Treatment: immune system (no cure)

Describe HIV: how it spreads, its effects on the body, and prevention/treatment. (Viral)

• Spread: sexual contact, bodily fluids, shared needles

• Symptoms: flu-like; weakens immune system

• Effect: destroys white blood cells → leads to AIDS

• Treatment: no cure; antiretroviral drugs slow progression

• Prevention: condoms, not sharing needles, screened blood

Describe tobacco mosaic virus: how it spreads and its effects on plants. (Viral)

• Spread: contact between infected plants / tools

• Symptoms: mosaic (discoloured) leaves

• Effect: reduces photosynthesis → stunted growth

• Treatment: no cure; remove infected plants

What is phagocytosis?

Phagocytosis is when white blood cells track a pathogen and bind to it. They engulf the pathogen which destroys the pathogen so it can’t do any harm.

What are antitoxins?

White blood cells produce Aunty toxins which bind to toxins that make us ill. They counteract the toxins so that they cannot do any damage to us.

How is skin a barrier to pathogens?

Skin is a physical barrier, but it also secretes oils and antimicrobial substances which kill pathogens

How are the mouth and nose barriers?

They have lots of little hairs and contain mucus which can trap pathogens

How are the trachea and oesophagus barriers?

They are lined of Cilia. Cilia can move particles to the back of the throat where the pathogens can be swallowed and they contain mucus.

What is the stomach a barrier?

The stomach contains hydrochloric acid so if any pathogens are swallowed, it can kill them as hydrochloric acid is very strong and kills nearly every pathogen

What are antibodies and what do they do?

• Proteins produced by lymphocytes

• Specific shape → binds to a specific antigen (lock-and-key)

• Attach to antigens on pathogens

• Do not kill directly

• Mark pathogens so they are easier to destroy

• Help white blood cells (e.g. phagocytes) recognise and destroy the pathogen

What are memory cells and what do they do?

• Type of lymphocyte

• Formed during the first infection

• Some lymphocytes become memory cells instead of making antibodies straight away

• Stay in the body long-term

• Specific to a particular antigen

• Second infection:

  • recognise the same antigen immediately

  • divide rapidly

  • produce lots of plasma cells

  • leads to rapid antibody production

• Result: faster response, often no symptoms

What are antibiotics?

Antibiotics kill bacteria and prevent new bacteria from growing which is what is making us ill. They can do this without killing or damaging body cells.

What is antibiotic resistance?

Antibiotic resistance is when an antibiotic is no longer effective towards a specific bacteria because it has been overused therefore the bacteria mutates and survives when antibiotics are used and reproduces passing on the resistance making antibiotics not effective.

Why can’t you use antibiotics for viruses?

Viruses height within our body cells antibiotics would not be able to find in target them and antibiotics could not kill the viruses without killing our body cells

What is efficacy?

Efficacy is how well the drug works are giving the effect you’re looking for for example how well an antibiotic kills bacteria

What is toxicity?

Toxicity is how harmful the drug is for example what the side-effects are and how bad they are

What is dosage?

Dosage is how much of what concentration of the drug should be given

What is stage one of testing a new drug?

Stage one is pre-clinical testing where drugs are tested on human cells and tissues that are grown in laboratory. This means you can test lots of substances cheaply but it cannot tell us how it affects a whole organism or individual organ.

What is stage two of testing a new drug?

Stage two is animal testing it is when you test on live animals specifically mammals as humans also mammals in the UK we must test new drugs on at least two live mammals for example mice and rabbit and it helps to give us a good idea of efficacy toxicity

What is stage three of testing new drugs?

Stage three is clinical testing. It is when you give a low dosage to a healthy volunteer and keep increasing the dose while managing side effects. If this goes okay you give it to the people who are suffering from the illness and the drug is actually four and you slowly increased dose until you hit optimum dosage

What is optimum dosage?

Optimum dosage is where efficacy is maximised and toxicity is minimise

How can you make clinical trials valid?

You can use placebo and do a double blind technique. This is where half of the people testing the new drug get a placebo which is a fake version of the drug normally assault or sugar tablet and it is double blind because the people getting it And the doctors do not know who is getting the real thing and who is getting the placebo