Understanding Health, Illness, and Immunity
Concept of Health
World Health Organization (WHO) Definition of Health: “The state of complete physical, mental, and social well-being and not merely the absence of disease or infirmity.”
Factors Influencing Health
- Lifestyle: Diet, physical exercise, stress level, consumption of alcohol, drugs, tobacco, etc.
- Environment: Pollution, radiation, toxic substances, pathogenic microorganisms.
- Genetic Factors: Genetic predisposition (resistance to some diseases), age (health often deteriorates with age).
- Healthcare System: Access to healthcare services varies depending on the country.
Understanding Illness
Illness occurs when one or more of the body’s organs does not function correctly. This often causes pain or discomfort.
- Symptoms: Only felt or experienced by the ill person (e.g., pain, tiredness).
- Signs: Can be seen by other people or detected in tests (e.g., blood pressure, temperature, rashes).
Non-Infectious Illnesses
- Not caused by pathogenic microorganisms, so they cannot be transmitted between human beings.
Examples: Cardiovascular diseases (heart attack, stroke), diabetes, cancer, mental disorders.
Infectious Illnesses
Caused by transmittable pathogenic microorganisms.
Two types of transmission:
- Direct Transmission: Directly from the infected person to another person (direct contact).
- Indirect Transmission: Transferred by an intermediary (e.g., food, water, utensils, objects, and other animals – vectors: insects, dogs, etc.).
Depending on the microorganism, they are:
- Virus: COVID-19, Flu, Herpes, HIV, mumps, rabies, measles, chickenpox.
- Bacteria: Tetanus, Salmonellosis, Pneumonia, Cholera.
- Protozoa: Malaria, Sleeping sickness, dysentery.
- Fungus: Candidiasis, Athlete’s foot.
Defenses Against Illnesses
External Defenses
(They prevent microorganisms from entering the body)
- They are non-specific defenses, reacting in the same way to all microorganisms.
- The skin and mucous membranes separate the inside of the body from the outside; microorganisms cannot easily cross them (physical defenses).
- Secretions like saliva or tears contain substances that fight microorganisms.
- Bacterial flora protect our skin and mucous membranes.
Internal Defenses (Immune Response)
- The internal defense system is formed by the immune system, which detects strange substances that enter our body and tries to destroy them.
Two types of immunity:
- Innate Immunity: We have it from birth. It is non-specific, acting against any type of pathogen. It involves phagocytosis (with macrophages).
- Acquired Immunity: We acquire it throughout our lives as a result of the body fighting different diseases. It is a specific response. We can also get this immunity through vaccines.
It is carried out by two types of cells:
- Lymphocyte T-Cells: Destroy cells that have been infected by microorganisms.
- Lymphocyte B-Cells: Produce antibodies against specific antigens. They also produce B-memory cells.