1. Concept of Health

Ancient Concept of Health

• Early Greeks (e.g., Hippocrates) and the Ayurveda system believed health depended on the balance of four “humors”.
• One humor was black bile.
• They believed people with excess black bile had a hot personality and suffered from fever.
• This was based on observation and philosophical thinking, not experiments.

Modern Scientific Concept

• William Harvey discovered blood circulation through experiments.
• The invention of the thermometer proved that people with black bile did not necessarily have higher body temperature.
• Thus, the humor theory was disproved.

Modern Definition of Health (WHO)

Health is a state of complete physical, mental, and social well-being, and not merely the absence of disease or physical fitness.

Three Components of Health

1. Physical Health

• Proper functioning of body organs
• Freedom from illness
• Good physical fitness

2. Mental Health

• Ability to think clearly
• Emotional stability
• Freedom from stress and anxiety

3. Social Health

• Good relationships
• Ability to work with others
• Positive participation in society

Factors Affecting Health

1. Genetic Disorders

Defects present from birth due to inheritance from parents.

Examples

• Haemophilia
• Sickle-cell anaemia
• Colour blindness

2. Infections

Diseases caused by microorganisms like:

• Bacteria
• Viruses
• Fungi
• Protozoa
• Helminths (worms)

3. Lifestyle Factors

• Balanced diet
• Safe drinking water
• Proper rest
• Regular exercise
• Personal hygiene
• Avoiding smoking, alcohol and drugs

Role of Mind in Health

Modern biology explains that:

Mind → Nervous System + Endocrine System → Immune System → Health

• Mental stress weakens immunity.
• Positive mental health improves resistance to disease.

Importance of Good Health

Good health leads to:

• Higher work efficiency
• Increased productivity
• Economic prosperity
• Longer lifespan (longevity)
• Lower infant mortality
• Lower maternal mortality
• Better quality of life

Measures to Maintain Good Health

• Balanced diet
• Personal hygiene
• Regular exercise
• Yoga
• Vaccination (Immunisation)
• Awareness about diseases
• Safe drinking water
• Hygienic food
• Proper waste disposal
• Control of disease vectors (mosquitoes, flies, etc.)

Yoga

Benefits:

• Improves physical fitness
• Reduces stress
• Enhances mental health
• Improves flexibility
• Strengthens immunity

Disease

Definition

A disease is a condition in which the normal functioning of one or more organs or body systems is disturbed, producing characteristic signs and symptoms.

Signs vs Symptoms

Classification of Diseases

1. Infectious (Communicable) Diseases

Definition

Diseases that spread from one person to another through pathogens.

Characteristics

• Caused by microorganisms
• Communicable
• Preventable by hygiene and vaccination

Examples

• Tuberculosis (TB)
• Malaria
• Typhoid
• Cholera
• Measles
• Chickenpox
• Influenza
• COVID-19
• AIDS

Important Point

Some infectious diseases like AIDS are fatal.

2. Non-Infectious (Non-Communicable) Diseases

Definition

Diseases that do not spread from one person to another.

Causes

• Genetic defects
• Nutritional deficiency
• Hormonal imbalance
• Lifestyle
• Ageing
• Cancer

Examples

• Diabetes
• Hypertension
• Cancer
• Heart disease
• Asthma
• Haemophilia

Important Point

Among non-infectious diseases, cancer is a major cause of death.

Drug and Alcohol Abuse

Drug and alcohol abuse:

• Damages the brain
• Affects liver and heart
• Weakens immunity
• Reduces work efficiency
• May lead to addiction and mental disorders

NEET Important Flow Chart

Health
│
├── Physical Well-being
├── Mental Well-being
└── Social Well-being
        │
        ▼
Factors Affecting Health
│
├── Genetic Disorders
├── Infections
└── Lifestyle
        │
        ▼
Good Health
│
├── Balanced Diet
├── Hygiene
├── Exercise
├── Yoga
├── Vaccination
├── Waste Disposal
└── Vector Control
        │
        ▼
Disease
│
├── Infectious
│     ├── Communicable
│     └── Example: TB, Malaria, AIDS
│
└── Non-Infectious
      ├── Non-communicable
      └── Example: Cancer, Diabetes

NCERT & NEET Important Points

• Health is not merely the absence of disease.
• Health includes physical, mental, and social well-being.
• Mind influences health through the nervous system, endocrine system, and immune system.
• Health is affected by genetic disorders, infections, and lifestyle.
• Balanced diet, hygiene, exercise, yoga, vaccination, waste disposal, and vector control help maintain health.
• Infectious diseases are communicable.
• Non-infectious diseases are non-communicable.
• Cancer is a major non-infectious disease.
• AIDS is an infectious and fatal disease.

One-Line Revision

• Health = Physical + Mental + Social well-being
• Disease = Disturbed body function
• Infectious = Communicable
• Non-infectious = Non-communicable
• Good health → Higher productivity + Longer life
• Balanced diet + Hygiene + Exercise + Vaccination = Healthy life