Health and Disease: Factors, Prevention, and Immunity

Health and Disease: A Comprehensive Overview

Health Encompasses: Sickness absence and well-being in physical, mental, emotional, social, spiritual, sexual, and environmental aspects.

Risk Factors for Health

• Food rich in fat and/or sugar
• Tobacco and/or drug use
• Lack of hygiene
• Stress

International Sanitary Conference (Paris, 1851)

Accomplishments:

• Development of public health policies with laws governing food handling and potable water.
• Creation of the National Institute of Health.
• Methods for preventative health planning, including vaccination and infection control.
• Improved diagnostic techniques.
• Drug development.
• Promotion of better nutritional habits for a healthy life.

Infectious Diseases

Infectious diseases are caused by microorganisms and are transmitted from one individual to another. These microorganisms include:

• Bacteria: Infect body tissues (e.g., Tuberculosis) or produce toxins.
• Viruses: Particles without cellular structure that live within cells and destroy the infected cells. Some viruses exhibit latency, remaining dormant within cells. Examples include influenza, measles, chickenpox, hepatitis, HIV, and rubella.
• Fungi
• Parasites: Organisms, such as unicellular protozoa or invertebrate parasites (e.g., nematodes, Platyhelminthes).

Infection Transmission

• Direct skin contact with a sick individual or contaminated objects (e.g., measles, varicella).
• Airborne transmission (e.g., flu, pneumonia, common cold).
• Contaminated water or food.

Antibiotics

Antibiotics are medicines that destroy bacteria without damaging the cells of the infected organism.

Lymphatic System

The lymphatic system is composed of lymphoid organs, lymph vessels, and various cell types, including white blood cells (e.g., lymphocytes [T cells for viruses and B cells for antibodies], macrophages [engulf germs]).

Functions:

• Collect accumulated interstitial fluid and return it to the bloodstream (when the fluid is within the lymphatic vessels, it is called lymph).
• Carry fats and fat-soluble vitamins.
• Contribute to the body's defense against diseases.

Lymphoid Organs: Red bone marrow, thymus, spleen, and tonsils (pharyngeal, appendix).

Lymphatic Capillaries: Include the thoracic duct (collects lymph from the lower limbs, abdomen, arm, head, and neck on the left side) and the right lymphatic duct (collects from the same regions on the right side).

Immune System

The immune system is responsible for defending the body against invading germs (antigens) and foreign cells.

Immunity is the body's capacity to defend itself against foreign substances.

• Non-specific Immunity: Non-selective rejection. Includes:
  • 1st Barrier: Skin and mucosal barriers of entry (e.g., digestive tract, respiratory tract).
  • 2nd Barrier: Inflammation.
  • 3rd Barrier: Complement system (proteins that destroy bacteria).
  • 4th Barrier: Natural killer cells (specialized lymphocytes that target cancerous cells).
• Specific Immunity: Involves antibodies (proteins produced against specific antigens).

Vaccines

Vaccines introduce inactivated viruses into the organism to stimulate the production of memory cells.

• Active Immunity: The organism produces antibodies after contact with the antigen.
• Passive Immunity: Used when there is no time to wait for the organism to produce antibodies; manufactured antibodies are provided from another organism.