B2.1 What are the causes of disease?

Pathogens 🦠:

• Bacteria: Single-celled organisms, can cause infections.

• Viruses: Infect cells and reproduce inside them.

• Fungi: Can be single-celled or multicellular, e.g., yeast and mushrooms.

• Protists: Single-celled eukaryotes, sometimes cause disease.

Communicable Diseases 🤒:

• Spread through direct contact, airborne particles, surfaces, or contaminated food/water.

• Examples: Influenza, Salmonella, Malaria.

Non-Communicable Diseases 🚫:

• Result from genetic, environmental, or lifestyle factors.

• Examples: Diabetes, Cancer.

Definitions:

• Antibiotic: Medicine that kills bacteria.

• Virus: Pathogen that reproduces inside host cells.

• Fungi: Eukaryotic pathogens, e.g., yeast.

• Protist: Single-celled eukaryotes, sometimes pathogenic.

B2.2 How do organisms protect themselves against pathogens?

Defenses 🛡:

• Mechanical barriers: Skin, nose hairs.

• Chemical barriers: Mucus, stomach acid, tears.

• Bacterial barriers: Gut bacteria.

Immune System 🧬:

• White blood cells: Attack and destroy pathogens.

• Antibodies: Proteins that neutralize pathogens.

Plant Defenses 🌿:

• Physical barriers: Cell wall, waxy cuticle.

• Antimicrobial substances: Chemicals that kill pathogens.

Definitions:

• Antibody: Protein produced by white blood cells.

• Antigen: Protein on pathogen surface.

• Immune system: Body's defense against pathogens.

B2.3 How can we prevent the spread of infections?

Plant Disease Prevention 🌱:

• Regulate infected plant movement.

• Sourcing healthy plants.

• Destroying infected plants.

Human and Animal Disease Prevention 🧴:

• Contraception.

• Sterilizing wounds.

• Hygiene and sanitation.

• Vaccination.

• Restricting travel.

Definitions:

• Vaccination: Introducing inactive pathogens to stimulate immunity.

• Contraception: Methods to prevent pregnancy.

• Sterilization: Removing microorganisms from equipment.

B2.4 How can we identify the cause of an infection?

Diagnosis Methods 🔬:

• Symptom observation.

• Cell counting.

• Culture growth.

• Microscopy and staining.

• Antimicrobial testing.

• Genome analysis.

Aseptic Techniques 🧼:

• Sterilize equipment.

• Limit sample exposure.

Monoclonal Antibodies 🧪:

• Used in diagnostic tests like pregnancy tests.

Definitions:

• Aseptic techniques: Methods to prevent contamination.

• Monoclonal antibodies: Lab-made antibodies for specific antigens.

B2.5 How can lifestyle, genes and the environment affect health?

Risk Factors ⚠:

• Unhealthy diet: High fats/sugar.

• Lack of exercise.

• Age.

• Genetic predispositions.

• Environmental factors: UV radiation.

• Smoking and drugs.

Disease Interactions 🔄:

• Autoimmune diseases.

• Viruses triggering cancers.

• Preventative diseases: Sickle cell anemia prevents malaria.

Definitions:

• Autoimmune disease: Immune system attacks the body.

• Correlation: Relationship between two variables.

• Genetic predisposition: Increased risk of disease due to genetics.

B2.6 How can we treat disease?

Medicines 💊:

• Painkillers: Reduce symptoms.

• Antibiotics: Kill bacteria.

Cardiovascular Disease Treatments ❤:

• Lifestyle changes.

• Drugs: Statins.

• Stents: Widen blood vessels.

• Heart transplants.

New Medicine Development 🧬:

• Screening.

• Pre-clinical trials.

• Clinical trials.

Monoclonal Antibodies 🧪:

• Used for cancer treatment by targeting specific cancer cells.

Definitions:

• Chemotherapy: Cancer treatment using drugs.

• Heart transplant: Replacing a damaged heart.

• Statins: Drugs lowering cholesterol.

Stent: Wire mesh widening arteries.