Human Health And Disease Class 12 Notes

What is Health?

In simple terms, Health can be defined as free from all diseases and infections. According to the World Health Organization (WHO), health is not only the absence of disease or illness. It is a state of an active and energetic condition including the physical, mental, and social well being. A balanced diet and regular exercise play an important role in maintaining a good health of an individual. There are many factors which affect health, such as:

  • Poorly balanced diet.
  • Genetic Disorders.
  • Stress, and anxiety.
  • Infection from pathogens.
  • Intake of unhealthy and unhygienic food.
  • Lack of exercise and other physical activities.

To maintain a good health, an individual should include a healthy and balanced diet, maintain a personal hygiene along with regular exercise and other physical activities. Everyone should be aware of the different types of diseases and the effects.

What are Diseases?

A disease is an abnormal condition affecting a healthy living organism. It is broadly divided into infectious and non-infectious.

Infectious diseases- These diseases are caused by the pathogens, such as bacteria, virus, fungi, parasites and can be easily transmitted from one person to another, hence it is also known as a contagious or communicable disease. Common Cold, Tuberculosis, flu, ringworm, malaria are some examples of infectious diseases.

Non-infectious diseases- Diseases which cannot be transmitted from one person to another are called non-infectious disease, it is also known as a noncommunicable disease. These diseases can be either caused by genetic disorders, unhealthy diets, lack of physical activity, excessive use of tobacco, drugs or alcohol and few environmental factors.


Immunity is defined as the ability of the body to protect, defend and fight against invading pathogens like bacteria, virus, and other foreign bodies and toxic substances. There are two types of immunity.

  • Innate immunity.
  • Acquired immunity.

Few Important Questions

  • Define Immunity and its types?
  • Define Addiction and Dependence?
  • What is Elisa? and what it is used for?
  • What is Cancer? Explain in brief about the types, diagnosis and treatment available for cancer?
  • List out the causes, symptoms, and available treatment for Influenza.

Learn more about human health and different types of disease from the topics given below:

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