Health and Disease – Important Points Class 12 Biology

Health and Disease – Important Points

Meaning of Health

  • Earlier, health was considered a balance of certain “humors” in the body.
  • Ancient Greek physician Hippocrates and the Indian Ayurveda system supported this idea.
  • People believed that excess “black bile” caused fever and hot personality.

Scientific Development of Health Concept

  • William Harvey discovered blood circulation using experimental methods.
  • Thermometer studies showed that people with “black bile” had normal body temperature.
  • This disproved the old “good humor” theory.

Modern Definition of Health

Health is a state of:

  1. Physical well-being
  2. Mental well-being
  3. Social well-being

Health does not mean only absence of disease or physical fitness.

Importance of Good Health

  • Increases working efficiency
  • Improves productivity
  • Brings economic prosperity
  • Increases life span (longevity)
  • Reduces infant mortality
  • Reduces maternal mortality

Ways to Maintain Good Health

  • Balanced diet
  • Personal hygiene
  • Regular exercise
  • Practice of yoga
  • Awareness about diseases
  • Vaccination (immunisation)
  • Proper disposal of wastes
  • Control of disease vectors
  • Clean food and water

Disease

  • When one or more organs or body systems do not function properly, disease occurs.
  • Disease is identified by various signs and symptoms.

Types of Diseases

1. Infectious Diseases

  • Spread from one person to another.
  • Caused by pathogens.
  • Common examples:
    • Cold
    • Flu
    • AIDS

2. Non-infectious Diseases

  • Do not spread from person to person.
  • Examples:
    • Cancer
    • Diabetes

Harmful Effects of Drug and Alcohol Abuse

  • Damage physical and mental health
  • Reduce body efficiency
  • Affect nervous system and organs

Factors Affecting Health

Health is affected by:

(i) Genetic Disorders

  • Defects inherited from parents
  • Disorders present from birth

(ii) Infections

  • Diseases caused by microorganisms

(iii) Lifestyle

  • Food and water intake
  • Rest and exercise
  • Personal habits

Role of Mind and Immune System

  • Mind influences the nervous system and endocrine system.
  • These systems affect the immune system.
  • A healthy mental state helps maintain good health.

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