Human Health: Genetics, Environment, and Disease

The quality of life of a person is defined as their degree of prosperity, happiness, and satisfaction, which allows them to act and feel life in a positive way.

Genes, Lifestyle, and Health

The health of a person is the result of the interaction between their genotype and the environment in which they develop and live.

• There are genetic diseases due to alterations in the genome.
• In other cases, the genotype does not directly determine the presence of the disease, but rather a predisposition to it.
• A group of diseases related to genetic diseases are caused by certain congenital disorders produced during embryonic development, such as Down syndrome.

Environmental Chemical Attacks

These are divided into two main groups:

Air Pollution

This is caused especially by industries, heating, and traffic. Key pollutants include:

• Carbon monoxide: Very toxic to humans.
• Sulfur dioxide: Causes difficulty in breathing due to spasms or contraction of the bronchi.
• Nitrogen oxides: Affect the lungs and are toxic.
• Suspension particles: May be solid or liquid.

Water Pollution

Domestic use and industrial water pollutants degrade organic, inorganic, or biological matter:

• Organic: Sewage, livestock waste, pesticides, grease, and plastics.
• Inorganic: Nitrates and phosphates from fertilizers.
• Biological: Microorganisms.

Food Contamination

Food is considered contaminated when strange substances are present within it.

Defense Mechanisms

Our body prevents infection through two types of mechanisms:

• Nonspecific defense mechanisms: These defend us against any infection.
• Specific defense mechanisms: Directed against each specific microorganism that enters us; these are the immune system mechanisms.

Nonspecific Mechanisms

Our body has several barriers to avoid being invaded:

• The skin: An insurmountable barrier to most microorganisms.
• Mucosal epithelia: These line the body cavities in contact with the outside.
• Inflammation: A body's response when an organism or foreign particle reaches the inside.

Specific Mechanisms: The Immune System

The most important components of the immune system are white blood cells called lymphocytes, which recognize any organism outside the body. There are two types:

• B cells and antibodies: Antibodies are proteins called immunoglobulins that bind to antigens. B lymphocytes produce antibodies; coated microorganisms are marked so that other white blood cells can destroy them.
• T cells: These also play a critical role in the immune response.

Cardiovascular Diseases

These are diseases of the heart and blood vessels. They are a major cause of death in developed countries. The most common are:

• Myocardial infarction: This occurs because a portion of the heart muscle's blood supply runs out, usually by the occlusion of the coronary arteries supplying it.
• Stroke: Occurs when blood flow is interrupted to a part of the brain, usually because a blood clot blocks an artery.