Health and Disease

Health is a state of complete physical, mental and social well-being, not merely the absence of disease or infirmity.
A healthy lifestyle includes regular exercise, a balanced diet, and limiting consumption of substances that can harm the body, like alcohol and tobacco.
Factors such as genetics, diet, stress, and environmental conditions all contribute to an individual’s health.

Diseases are conditions that impair normal tissue function. There are two main categories of diseases: communicable (infectious) diseases and non-communicable diseases.
Communicable diseases are caused by pathogens such as bacteria, viruses, parasites or fungi. They can be spread, directly or indirectly, from one person to another. Examples include influenza, HIV/AIDS, and the common cold.
Non-communicable diseases are not infectious and cannot be spread from person to person. These are often long-term and progress slowly. Examples include heart disease, diabetes, and most cancers.

The body has both non-specific defenses and specific defenses to combat pathogens.
Non-specific defenses work against a wide range of pathogens. These include physical barriers like skin and mucous membranes, and internal defenses like phagocytic white blood cells and inflammatory responses.
Specific defenses, also known as the immune system, involve lymphocytes - B cells and T cells. They have a memory function that leads to immunity from re-infection by the same pathogen.

Lifestyle choices greatly impact health. Physical inactivity, unhealthy diet, and excessive use of alcohol and tobacco increase the risk of non-communicable diseases.
Regular physical activity helps to maintain a healthy weight, reduces stress, and boosts the immune system.
A balanced diet, rich in fruits and vegetables, lean proteins, whole grains and low in saturated fats and sugars, provides the body with essential nutrients needed for good health.

Health screening is used to identify diseases before symptoms appear, allowing early treatment and management.
Vaccinations are a method of creating immunity to certain diseases by stimulating the body’s immune response. They significantly reduce the risk of contracting several communicable diseases.

Socioeconomic factors, such as income level, education, housing and employment conditions, can significantly affect health.
Individuals from disadvantaged socioeconomic backgrounds often have poorer health outcomes due to limited access to healthcare, poor diet, and higher levels of stress.