OCR GCSE Biology: Health and Disease – Causes, Prevention, and Treatment

OCR GCSE Biology: Health and Disease – Causes, Prevention, and Treatment

1. Communicable Diseases and Pathogens

Communicable diseases are illnesses that can spread from person to person or from animals to humans. These diseases are caused by pathogens, microscopic organisms that invade the body and cause harm.

Types of pathogens:

• Bacteria: Single-celled organisms that can cause infections like pneumonia and food poisoning.
• Viruses: Non-living particles that replicate inside host cells, leading to diseases like the flu and HIV.
• Fungi: Multicellular organisms that can cause skin infections like athlete's foot and fungal lung infections.
• Protozoa: Single-celled eukaryotic organisms that can cause diseases like malaria.

Transmission of communicable diseases:

• Direct contact: Touching an infected person or animal.
• Indirect contact: Touching contaminated objects like doorknobs or utensils.
• Droplet infection: Inhaling droplets from an infected person's cough or sneeze.
• Airborne transmission: Inhaling airborne pathogens like viruses or bacteria.
• Waterborne transmission: Ingesting contaminated water.
• Foodborne transmission: Ingesting contaminated food.

2. The Body's Defenses: Immune Response

The immune system is the body's natural defense against pathogens. It consists of various cells and organs that work together to identify and destroy foreign invaders.

Components of the immune system:

• White blood cells: Specialized cells that fight infections.
• Antibodies: Proteins produced by the body to target specific pathogens.
• Lymphatic system: A network of vessels and tissues that transports immune cells and fluids.

Immune response stages:

1. Recognition: Immune cells identify foreign antigens on pathogens.
2. Activation: Immune cells activate and produce antibodies to target the pathogens.
3. Elimination: Antibodies and other immune cells destroy the pathogens.
4. Memory: Immune cells develop memory of the pathogen for future recognition and faster response.

3. Vaccination and Immunity

Vaccination is the process of introducing a weakened or inactive form of a pathogen into the body to stimulate an immune response. This allows the body to develop immunity against the disease without experiencing the full-blown illness.

Types of vaccines:

• Live-attenuated vaccines: Contain weakened versions of the pathogen.
• Inactivated vaccines: Contain killed pathogens.
• Subunit vaccines: Contain specific parts of the pathogen.

Benefits of vaccination:

• Protection against infectious diseases: Vaccines significantly reduce the incidence and severity of many diseases.
• Herd immunity: When a large percentage of the population is vaccinated, it becomes difficult for diseases to spread, protecting even those who cannot be vaccinated.

4. Non-Communicable Diseases and Risk Factors

Non-communicable diseases are chronic illnesses that are not contagious. They are often caused by a combination of genetic, lifestyle, and environmental factors.

Common non-communicable diseases:

• Cardiovascular disease: Conditions affecting the heart and blood vessels, such as heart attacks and strokes.
• Cancer: Uncontrolled cell growth and division that can form tumors.
• Diabetes: A metabolic disorder where the body cannot regulate blood sugar levels.
• Respiratory diseases: Conditions affecting the lungs, such as asthma and chronic obstructive pulmonary disease (COPD).

Risk factors for non-communicable diseases:

• Genetics: Some individuals are genetically predisposed to certain diseases.
• Lifestyle factors: Diet, exercise, smoking, alcohol consumption, and stress levels.
• Environmental factors: Air and water pollution, exposure to harmful substances, and access to healthcare.

5. Investigating Health Data and Ethical Considerations

Analyzing health data helps scientists and healthcare professionals understand disease trends, identify risk factors, and develop effective interventions.

Types of health data:

• Mortality rates: The number of deaths from a specific disease per population.
• Morbidity rates: The number of cases of a disease per population.
• Prevalence: The proportion of people in a population who have a disease at a given time.
• Incidence: The number of new cases of a disease per population over a specific time period.

Ethical considerations in health research:

• Informed consent: Individuals participating in research must be fully informed about the risks and benefits of the study.
• Confidentiality: Personal information about participants must be kept confidential.
• Beneficence: Research should aim to benefit participants and society.
• Justice: Research should be conducted fairly and equitably, ensuring that all groups have access to its benefits.

6. Medicine Development and Treatment

Drug development is a complex process involving multiple stages of research and testing.

Stages of drug development:

1. Discovery and preclinical testing: Identifying potential drug candidates and testing their safety and efficacy in laboratory settings.
2. Clinical trials: Testing the drug in humans in different phases to assess safety, efficacy, and dosage.
3. Regulatory approval: Submission of data to regulatory agencies for approval to market the drug.
4. Post-marketing surveillance: Monitoring the drug's safety and effectiveness after it is released to the public.

Types of medical treatments:

• Drug therapy: Using medications to treat disease symptoms or prevent disease progression.
• Surgery: Performing operations to treat or remove diseased tissues.
• Radiotherapy: Using radiation to destroy cancer cells.
• Immunotherapy: Stimulating the immune system to fight disease.
• Lifestyle modifications: Changing diet, exercise, and other habits to manage disease risk factors.