Human Health and Disease

Notes

Chapter 7: Human Health and Disease

1. Introduction – Human Health

Health can be defined as a state of complete physical, mental and social well-being.

Health is affected by three major factors:

• Genetic disorders: Disorders which a child inherits from parents from birth.
• Infections: Diseases caused due to pathogens or disease-causing organisms.
• Lifestyle: It includes our habits such as intake of food and water, rest and exercise, which influence our health.

When people are healthy, they are more efficient at work. This increases productivity and contributes to economic prosperity.

2. Factors Responsible for Maintaining Good Health

• Balanced diet: A diet containing all essential nutrients in proper proportion.
• Personal hygiene
• Regular exercise, meditation and yoga
• Awareness about diseases
• Proper disposal of wastes
• Control of vectors
• Maintenance of hygiene

3. Disease

A disease is a condition in which one or more organs of the body do not work properly. It is generally characterised by various signs and symptoms.

The organisms which cause diseases are called pathogens.

4. Types of Diseases

Diseases can broadly be classified into:

• Congenital diseases: Genetic disorders present from birth, for example Down syndrome.
• Acquired diseases: Diseases developed after birth.

Acquired diseases may further be divided into:

• Communicable or infectious diseases
  • Bacterial diseases – example: Typhoid
  • Viral diseases – example: Common cold
  • Protozoan diseases – example: Malaria
  • Helminthic diseases – example: Filariasis
  • Fungal diseases – example: Ringworm
• Non-communicable or non-infectious diseases
  • Deficiency diseases – example: Beriberi
  • Degenerative diseases – example: Heart disease
  • Allergic diseases – example: Asthma
  • Cancer

Note: Diseases associated with the way a person or a group of people lives are called lifestyle diseases, for example arthritis and obesity.

5. Infectious and Non-Infectious Diseases

Infectious diseases: Diseases which can be transmitted from an infected person to another healthy person.

Viral and bacterial infections are common causes of infectious diseases. However, fungi and protozoans can also cause infections.

Non-infectious diseases: Diseases which are not transmitted from an infected person to another person. They may be caused by factors such as deficiency or malfunctioning of organs.

Infectious Diseases

6. Bacterial Diseases

6.1 Typhoid

• Caused by: Salmonella typhi
• Affects: Small intestine and may migrate to other parts of the body through blood.
• Transmission: Contaminated food and water.