Health: The Ultimate Treasure
Chapter Notes — Science Class 8
Have you ever wondered what it really means to be healthy? Is it just not being sick, or is there more to it? Good health includes our body, mind, habits, and relationships with others. Let us explore simple and practical ways to stay healthy and prevent diseases.
1. Health: Is It More Than Not Falling Sick?
Health is not just about not being sick. It means feeling good in your body, mind, and social life. According to the World Health Organization (WHO), health is a state of complete physical, mental, and social well-being, not just the absence of disease.
A Healthy Person Can
Do tasks efficiently.
Handle difficult situations well.
Get along with friends and other members of society.
Key Aspects of Health
Physical health: Taking care of the body through proper food, exercise, and sleep.
Mental health: Staying positive and managing stress and difficult feelings.
Social health: Having good relationships with friends, family, and other people.
2. A Student's Story
A Class 8 boy moved to a new city and school. He felt lonely because he had no friends and his parents were busy. He spent more time on his phone and social media. This made him feel worse and led to the following problems:
Headaches.
Weight loss.
Trouble sleeping.
Cause and Solution
A doctor suggested reducing screen time and meeting a counsellor. The counsellor helped the boy make friends, and his health improved.
Loneliness and excessive screen time caused both physical and mental health problems.
Making new friends and receiving support from adults helped him feel better.
3. Ayurveda and Health
Ayurveda teaches that health is related to a balance among the body, mind, and surroundings.
Daily and Seasonal Routines: It gives importance to a daily routine (dinacharya) and a seasonal routine (ritucharya).
Diet: It encourages eating fresh and wholesome food suited to one's prakriti, or body type.
Mind and Body Practice: It gives importance to regular exercise, cleanliness, restful sleep, and a calm mind through yoga, meditation, and mindfulness.
4. How Can We Stay Healthy?
Staying healthy involves:
Eating nutritious food.
Keeping clean, including maintaining personal hygiene and clean surroundings.
Exercising regularly.
Getting enough sleep.
Spending time with family and friends.
Having a positive attitude.
5. Good and Bad Habits
Good Habits
Keep yourself clean and maintain personal hygiene.
Eat a healthy and balanced diet.
Exercise regularly.
Make time to relax or meditate every day.
Bad Habits
Bad habits can harm our health. They include:
Spending too much time on mobile phones or screens.
Eating fast food or junk food every day.
Sleeping very late or not getting enough sleep.
Skipping meals, especially breakfast.
6. Maintaining a Healthy Lifestyle
Our health depends on many factors. These include our lifestyle, which means the way we live, and our environment, which means our surroundings.
Balanced Diet: Eat a balanced diet containing plenty of fruits, vegetables, and whole grains. Limit junk food and foods and drinks high in fat or added sugar.
Physical Activity: Stay physically active. Play outdoors, walk, run, cycle, or exercise.
Screen Time: Limit screen time and spend more time in nature.
Sleep: Get enough sleep to help the body and mind rest.
Mindfulness: Practise yoga or pranayama, which consists of simple breathing exercises, regularly.
Say 'NO' to Harmful Substances: Say 'NO' to harmful substances such as tobacco, alcohol, and addictive drugs.
7. Keeping the Environment Clean
Playground Safety: A clean and well-maintained playground is safer and healthier for playing, whereas a dirty and polluted playground may contain flies and mosquitoes and can make us sick.
Clean Air and Water: Clean air and water are important for good health. Pollution from vehicles or factories can cause coughing and breathing problems such as asthma.
Air Quality Index (AQI): The Air Quality Index (AQI) shows how clean or polluted the air is.
Surroundings Hygiene: Avoid littering and keep your area tidy. A clean environment reduces the risk of diseases and helps us stay healthy and feel good.
8. Importance of Feelings and Relationships
Mental & Emotional Aspect: Health is not just about the body; feelings and relationships matter too.
Impact of Loneliness: Even with good food and clean surroundings, a person may feel unhappy if they are lonely or upset.
Social Connection: Spending time with friends and family, talking, laughing, and having fun helps keep the mind healthy.
9. How Do We Know That We Are Unwell?
Our body usually works in a specific way to keep us healthy. When we feel unwell, something inside our body may not be working properly. We experience symptoms and signs that show that we are not healthy.
Symptoms vs. Signs
Symptoms: What we feel when we are unwell. Examples: Pain, tiredness, and dizziness.
Signs: Changes that can be seen or measured by another person, such as a doctor. Examples: Fever (high body temperature), rash, high blood pressure, and swelling.
10. Diseases: What Are the Causes and Types?
A disease is a condition that stops the body or mind from working normally. It happens when one or more organs or organ systems do not function properly.
Causes of Diseases
Pathogens: Germs such as bacteria, viruses, fungi, worms, or protozoa (single-celled organisms) can cause diseases.
Poor Nutrition: Not eating enough healthy food can lead to deficiency diseases.
Unhealthy Lifestyle: Habits such as lack of exercise or an unhealthy diet contribute to diseases.
Two Major Types of Diseases
Communicable Diseases: Diseases that can spread from one person to another (caused by pathogens). Examples: Typhoid, dengue, flu, chickenpox, COVID-19.
Non-Communicable Diseases: Diseases that cannot spread from person to person. Linked to lifestyle, diet, environment, or organ function. Examples: Diabetes, cancer, heart disease, asthma.
11. How Are Communicable Diseases Caused and Spread?
All communicable diseases are caused by pathogens that enter our body through various routes:
Air: Transmitted when pathogens in tiny droplets are released by coughing, sneezing, or talking and breathed in by others (e.g. flu, tuberculosis).
Direct Contact: Touching an infected person, for example, while shaking hands.
Indirect Contact: Sharing items such as towels or handkerchiefs.
Contaminated Food or Water: Consuming unsafe food or water contaminated with bacteria, viruses, or parasites (e.g. cholera, typhoid).
Vectors: Insects such as mosquitoes transmit malaria and dengue. Houseflies carry pathogens to food.
12. Prevention of Communicable Diseases
Keep yourself and your surroundings clean.
Practise good hygiene, such as washing your hands with soap.
Cover your mouth and nose when coughing or sneezing.
Wear a mask in crowded places when required.
Avoid sharing personal items such as towels and handkerchiefs.
Keep food and water clean.
Stay at home and rest when unwell to recover and prevent spreading disease.
Use mosquito nets and repellents and control insect breeding.
13. How Are Non-Communicable Diseases Caused?
Non-communicable diseases (NCDs) are not caused by infections or germs. Instead, they are linked to:
Lifestyle Factors: Unhealthy habits such as eating too much junk food, lack of exercise, smoking, or excessive stress lead to diabetes, heart disease, or cancers.
Nutritional Deficiencies: Lack of essential nutrients cause deficiency diseases: Vitamin C deficiency causes scurvy, Iron deficiency causes anaemia, Iodine deficiency causes goitre.
Environmental Factors: Pollution and harmful chemicals contribute to asthma and cancers.
Hormonal Imbalances: Imbalances of hormones in the body (e.g., diabetes).
Chronic Nature: NCDs usually last for a long time (often > 3 months) and require ongoing care.
14. How to Prevent and Control Diseases?
You may have heard the saying: "Prevention is better than cure." This means it is easier and wiser to prevent a disease than to try to cure it after becoming sick. Good sanitation and cleanliness are simple and effective ways to reduce disease spread.
Case Study — Odisha: Community-Led Sanitation Campaign
Location & Action: In Bhadrak district, Odisha, a community campaign encouraged people to build and use toilets.
Impact: As families stopped open defecation, child health improved and diseases such as diarrhoea and infections were greatly reduced.
Takeaway: Building toilets, keeping surroundings clean, and disposing of waste properly prevents germs from spreading. Community action has a major impact on public health.
15. Ability of the Body to Fight Diseases (Immunity & Vaccines)
The ability of the body to fight diseases is called immunity. Our immune system is a group of special cells, tissues, and organs that recognise and fight harmful germs.
Role of Vaccines
Acquired Immunity: Vaccines are injections or drops that teach the immune system to recognise and destroy specific germs before they make us sick.
How They Work: Vaccines use harmless parts, dead, or weakened forms of a germ. Example: Tetanus shot contains an inactivated bacterial toxin.
Common Vaccines: Vaccines against polio, measles, hepatitis, and other diseases are given during childhood.
Edward Jenner and the Smallpox Vaccine
Discovery: In the late 1700s, Edward Jenner observed that people who had cowpox did not get smallpox. He prepared the first vaccine using material from cowpox sores, leading to global eradication of smallpox.
Variolation in India: Earlier in India, variolation involved using a small amount of material from a mild smallpox infection to protect healthy people.
Importance of Vaccines & India's Role
Disease Prevention: Vaccines prevent serious illnesses before a person becomes sick.
Community Protection: High vaccination rates create herd protection, guarding those who cannot be vaccinated.
Safety: Vaccines are thoroughly tested for safety.
India's Global Role: India is a major global vaccine producer, supplying vaccines worldwide and playing a key role during the COVID-19 pandemic.
16. Treatment of Diseases & Antibiotics
If our immune system cannot fight off an infection, doctors prescribe medicines, including antibiotics when required.
What Are Antibiotics?
Definition: Medicines used to kill bacteria or stop them from multiplying (e.g. treating tuberculosis, typhoid).
Crucial Limitation: Antibiotics DO NOT work against viral infections such as colds, flu, or COVID-19.
Discovery of Antibiotics
Alexander Fleming (1928): Discovered penicillin in London after observing that mould on a Petri dish killed harmful bacteria around it.
Antibiotic Resistance
Definition: Occurs when bacteria change and stop being killed by antibiotics, making infections much harder to treat.
Causes: Taking antibiotics for viral infections, not finishing prescribed doses, and overuse of antibiotics in farm animals and crops.
17. Managing Non-Communicable Diseases
Diseases such as diabetes, cancer, and heart disease are managed through:
Taking prescribed medicines as advised by doctors.
Healthy lifestyle changes in diet and exercise.
Rehabilitation (special help to recover or function better).
Early diagnosis and regular health check-ups.
18. Key Points to Remember
Health Definition: Health means complete physical, mental, and social well-being, not just freedom from diseases.
Happiness & Health: Being happy helps us stay active and healthy; good health improves mood.
Disease: A condition that stops the body or mind from working normally.
Symptoms vs. Signs: Symptoms are felt by the person (pain, tiredness); signs are visible/measurable (fever, rash).
Communicable Diseases: Caused by pathogens (bacteria, viruses, fungi, worms) and spread between people or via air, water, food, contact, or vectors.
Non-Communicable Diseases: Not caused by germs; linked to lifestyle, diet, environment, or hormonal imbalances.
Hygiene & Sanitation: Good personal hygiene and clean surroundings are essential to prevent disease spread.
Immunity & Vaccines: The immune system fights germs; vaccines train it safely to provide acquired immunity.
Antibiotics: Treat bacterial infections only; misuse causes dangerous antibiotic resistance.
Golden Rule: 'Prevention is better than cure' — healthy habits, vaccination, cleanliness, and staying informed protect our health.
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