Understanding Health, Disease, and Environmental Impacts

Defining Health and Illness

Currently, the WHO defines health as a state of complete physical, mental, and social well-being, not merely the absence of disease.

Disease is defined as an altered state of health, meaning a temporary or permanent loss of physical, mental, or social well-being.

The quality of life of a person is broadly defined as the degree of comfort, happiness, and satisfaction, which allows them to act and feel their life positively.

Life expectancy at birth is an estimate of the average years a group of people born in a given year would live, assuming current health and social conditions in the area being studied remain constant.

Genetic and Congenital Conditions

Genetic diseases are due to alterations in the genome (e.g., Down syndrome, hemophilia). In other cases, the genotype does not directly determine the presence of the disease but creates a predisposition (e.g., allergies).

Congenital diseases are those that manifest from birth, due to some disturbance occurring during embryonic development or during the birth process.

Primary Causes of Illnesses

Illnesses are generally caused by factors related to:

• The environment around us
• The body itself (internal malfunctions)
• Life habits (lifestyle choices)
• The sociocultural environment

Major Categories of Diseases

Diseases affecting us include:

• Infectious: Caused by bacteria and viruses (e.g., cholera, influenza, AIDS).
• Tumor: Characterized by a lack of control of cell proliferation (cancers).
• Blood/Hormonal: Endocrine alterations (e.g., diabetes and obesity).
• Mental: Alterations of rational processes (e.g., depression, schizophrenia, dementias).
• Nervous System: Disorders like meningitis and various neuropathies.
• Respiratory: Disorders of the respiratory system (e.g., sinusitis, asthma).
• Gastrointestinal: Alterations of the digestive system (e.g., caries, cirrhosis, appendicitis).
• Skin: Impaired function (e.g., dermatitis, urticaria).
• Musculoskeletal: Alteration of muscles, bones, and joints (e.g., osteoporosis, scoliosis).
• Congenital and Genetic: Changes present from birth (e.g., Down syndrome, anencephaly).
• Lesions: Caused by external trauma (e.g., physical injuries, burns).

Environmental Assaults on Health

Physical Environmental Assaults

• Ionizing Radiation: A form of energy capable of modifying the structure of matter.
• Noise Pollution: Most of the world's population lives in noisy cities. Noise is unwanted sound that can cause sleep and behavioral disturbances.
• Temperature Variations: High temperatures combined with excessive humidity prevent sweat evaporation and subsequent cooling, which can be lethal.

Chemical Environmental Assaults

Contamination through various mediums:

• Air Pollution: (e.g., carbon monoxide, sulfur dioxide, nitrogen oxide, suspended particles).
• Water Pollution: (organic, inorganic, and biological contaminants).
• Food Contamination: (foreign substances).

Infectious Diseases and Transmission

Infectious diseases are those caused by pathogenic microorganisms, including bacteria, viruses, protozoa, and fungi.

Examples of Pathogenic Microorganisms include Salmonella, influenza viruses, and ringworm fungi.

Pathogens and Transmission Routes

Infectious diseases are transmitted through several routes:

• Direct Contact: Skin diseases, respiratory illnesses, and sexual transmission.
• Water
• Food
• Animals (vectors)

Examples of Pathogen Transmission

• Bacteria: Cholera (via water), Strep (via air).
• Viruses: Flu (by direct contact), Mumps (by direct contact).
• Protozoa: Amebiasis (through water and food), Malaria (mosquito bite).
• Fungi: Candidiasis (by sexual contact), Histoplasmosis (by air).