Understanding Health, Illnesses, and the Immune System

Posted on Dec 6, 2024 in Biology

Health and Its Determinants

What is Health?

Health is a state of complete physical, mental, and social well-being.

Determinants of Health

Several factors contribute to health:

  1. Biological Determinants: An individual’s physiological characteristics.
    • Negative Example: Increasing age and the tendency to develop short-sightedness.
    • Positive Example: Having teeth resistant to decay.
  2. Environmental Determinants: Features of our surroundings.
    • Negative Examples: Excessive and continuous noise, the presence of pathogenic organisms.
    • Positive Example: Fresh air.
  3. Lifestyle Determinants: Habits reflecting an individual’s or group’s way of life. These include:
    • Maintaining basic personal hygiene.
    • Engaging in regular physical activity.
    • Avoiding harmful substances.
    • Refraining from self-medicating.
    • Getting enough sleep.
  4. Public Health Measures: Positive determinants involving the establishment of healthcare systems, including services for prevention, treatment, and rehabilitation.

Illnesses: Infectious and Non-Infectious

An illness is any physical or mental symptom that causes the body to malfunction.

  1. Non-Infectious Illnesses: Not caused by pathogens but develop due to other factors, such as injuries affecting different organs. These cannot be transmitted from one person to another.
  2. Infectious Illnesses: Caused by pathogens (viruses, bacteria, fungi, etc.) that enter the body and can be transmitted.
    • Direct Transmission: Pathogens pass directly from a sick person to a healthy person.
    • Indirect Transmission: Pathogens use different vehicles for transmission (water, animals, food), called vectors, to spread from a sick person to a healthy person.

The Immune System and Immune Response

The immune system comprises defense mechanisms that provide the human body with immunity, meaning resistance to infections caused by pathogens. The immune system’s response to pathogens is called the immune response.

Innate (Non-Specific) Immunity

Develops in the womb and protects the body from all invading pathogens. Non-specific defenses include:

  1. External Defenses: Skin (impermeable to microorganisms), mucous membranes, bodily secretions, and natural bacterial flora.
  2. Phagocytes: White blood cells that capture and digest pathogens using pseudopodia.
  3. Inflammatory Reaction: Occurs when we get a wound.

Acquired Immunity

Develops throughout life as we are exposed to different pathogens. It is a pathogen-specific immune response carried by lymphocytes and certain substances they produce.

Primary Humoral Immune Response

Occurs when a pathogen enters the body for the first time.

  1. Activation: Certain lymphocytes detect and activate to fight the pathogen.
  2. Multiplication and Antibody Production: Lymphocytes multiply by cell division and produce antibodies that bind to and destroy the pathogen.
  3. Acquisition of Immunological Memory: Some sensitized lymphocytes remain in the body as memory B lymphocytes.

Secondary Humoral Immune Response

Triggered by a second invasion by the same pathogen. Memory lymphocytes recognize the pathogen, activate, and divide rapidly, reducing the time needed to produce antibodies and destroying the pathogen more effectively.

Vaccines and Medications

Vaccines

Vaccines are synthetic substances containing inactive pathogens, unable to cause disease. They prevent diseases but do not cure them.

When administered, the immune system recognizes the inactive pathogen and triggers a primary humoral immune response. This is an artificial method of acquiring immunity without suffering from the disease. If a live pathogen infects a vaccinated person, the developed lymphocytes trigger a secondary humoral immune response, eliminating the pathogen and preventing illness.

Medications

Medications contain active ingredients that cure illnesses or relieve symptoms.

  1. Antibiotics: Destroy bacteria or prevent them from reproducing.
  2. Antivirals: Kill viruses without damaging virus-infected cells, helping to treat viral illnesses.
  3. Analgesics: Have no curative effect but alleviate or eliminate pain.