Meaning of health and healthy habits
Two cousins live in the same street. One never has a fever but sits alone on a phone all day, sleeps at 2 a.m. and feels gloomy. The other plays outside, eats home food and laughs with friends. Everyone says the second child is healthier, even though the first child is "not sick".
Health is a state of complete physical, mental and social well-being, not just the absence of disease. It depends mainly on our lifestyle (how we live) and our environment (our surroundings).
Key idea 1: Three sides of health — A healthy person looks after the body, keeps a positive mind and enjoys good relationships. Ayurveda also teaches that true health is a balance of body, mind and surroundings.
- Easy: WHO says health is complete physical, mental and social well-being.
- Medium: A student who feels lonely after moving to a new town may get headaches and lose sleep even if the food is good; the mind and social life are affected.
- Exam-type: Health is a wider idea than "not falling sick". A person with no disease who is always angry and isolated is not fully healthy.
In the figure: Each column is one side of health. Health is complete only when all three are cared for together.
Key idea 2: Healthy habits and a clean environment — Eat a balanced diet, stay active, sleep enough, limit screen time, practise yoga and say NO to tobacco, alcohol and drugs. Keep the surroundings clean, because flies and mosquitoes breed in dirt, and polluted air causes cough and asthma. The Air Quality Index (AQI) tells us how clean the air is.
- Easy: Getting enough sleep is a healthy habit; skipping breakfast daily is not.
- Medium: Too much screen time can cause dry eyes, poor sleep and anxiety, so it should be limited.
- Exam-type: Ayurveda's dinacharya is the daily routine and ritucharya is the seasonal routine; both help keep the balance of health.
Our health depends on both how we live (lifestyle) and where we live (environment).
Saying "health means not having any disease". WHO also includes mental and social well-being.
Think of a three-legged stool; take away one leg and it falls. Memory clue: Physical, Mental, Social = P-M-S, three legs of health.
Spot the difference
| Side of health | What it means | Example habit |
|---|---|---|
| Physical | the body works well | balanced diet, exercise |
| Mental | calm, positive mind | yoga, enough sleep |
| Social | good relationships | time with friends and family |
Practice questions
- 1How does WHO define health?
- 2Name the three sides of health.
- 3What does AQI tell us?
- 4Why do people living next to a garbage dump fall sick more often?
- 5Name two harmful effects of too much screen time.
- 6What do dinacharya and ritucharya mean?
- 7Kabir never gets fever but sleeps 4 hours and never exercises. Is his health perfect? Explain.
- 8A town has thick smoke every day. Suggest two steps to improve residents' health.
Show answers (try them yourself first)
- 1Complete physical, mental and social well-being, not just the absence of disease.
- 2Physical, mental and social.
- 3How clean the air is.
- 4Flies and mosquitoes breed there and spread germs.
- 5Dry eyes, poor sleep, anxiety (any two).
- 6Dinacharya is the daily routine; ritucharya is the seasonal routine.
- 7No. Health also needs enough sleep, activity and a happy mind; not falling sick is not enough.
- 8Reduce smoke from vehicles and factories, and plant more trees.
Symptoms, signs and kinds of disease
When you have a fever, you say, "I feel tired and my head hurts." The nurse puts a thermometer under your arm and says, "39 degrees." You told your feelings; she measured a number. Both help the doctor.
A disease is a condition that affects the normal working of the body or mind. A symptom is what we feel (pain, tiredness). A sign can be seen or measured (fever, rash, high blood pressure). Disease-causing organisms are called pathogens.
Key idea 1: Two kinds of disease — Communicable diseases are caused by pathogens and can spread from person to person. Non-communicable diseases are not caused by pathogens and do not spread.
- Easy: Typhoid, dengue, flu and chickenpox are communicable; diabetes, asthma and cancer are non-communicable.
- Medium: Pathogens include bacteria, viruses, fungi, protozoa and worms.
- Exam-type: Some diseases, such as scurvy, are caused by poor nutrition and no germ is involved, so they cannot be caught from others.
In the figure: The left side is caused by germs and spreads; the right side is linked to lifestyle, diet or environment and does not spread.
Key idea 2: Why non-communicable diseases are rising — In India they have become more common because people eat more processed food, exercise less and live longer. Most deaths in India now are due to non-communicable diseases.
- Easy: A thermometer reading is a sign; feeling tired is a symptom.
- Medium: Doctors use both symptoms and signs together to find what is making a person unwell.
- Exam-type: A village where many people drink the same flood water and fall ill together most likely has a communicable disease spread through water.
A disease does not always need a germ; poor food and unhealthy habits can also cause disease.
Thinking every disease spreads from person to person. Diabetes and asthma do not.
Think "catchable or not". Memory clue: Symptom = what I Say I feel; Sign = what the doctor can See or measure. Communicable = Catchable.
Spot the difference
| Point | Symptom | Sign |
|---|---|---|
| Who notices | the patient feels it | the doctor sees or measures it |
| Example | pain, tiredness | fever, rash, high blood pressure |
Practice questions
- 1What is a disease?
- 2What are disease-causing organisms called?
- 3Name two non-communicable diseases.
- 4Is a headache a symptom or a sign?
- 5Why can a non-communicable disease not spread from person to person?
- 6Name any three types of pathogens.
- 7Priya has itchy blisters and a mild fever; her uncle has had high blood sugar for years. Classify each disease.
- 8Rahul develops scurvy because his diet lacks vitamin C. Can his friends catch it from him? Why?
Show answers (try them yourself first)
- 1A condition that affects the normal working of the body or mind.
- 2Pathogens.
- 3Diabetes and asthma (or cancer).
- 4A symptom, because the patient feels it.
- 5It is not caused by a pathogen, so there is nothing to pass on.
- 6Bacteria, viruses, fungi, protozoa or worms (any three).
- 7Priya: likely communicable; uncle: non-communicable (diabetes).
- 8No. Scurvy is a deficiency disease with no pathogen, so it is non-communicable.
Spread and prevention of communicable diseases
In the rainy season, an old tyre behind the building fills with water. After a week, many mosquitoes buzz around the building and several neighbours get fever. Emptying the tyre is a very small job, yet it protects many people.
Pathogens spread through the air (cough, sneeze), through contaminated water and food, by direct contact or by sharing personal items, and through vectors such as mosquitoes and houseflies, which are insects that carry pathogens.
Key idea 1: Three main routes — Different diseases take different routes, so the prevention steps also differ.
- Easy: Chickenpox, cold and tuberculosis (TB) spread through the air; TB affects the lungs.
- Medium: Cholera, typhoid and hepatitis A spread through dirty water and food; hepatitis A affects the liver.
- Exam-type: Malaria (caused by a protozoan) and dengue (caused by a virus) are spread by mosquitoes; roundworms are parasites that live in the intestine and feed on our nutrients.
In the figure: Each column shows one route with example diseases and the best way to block it.
Key idea 2: Simple steps that protect everyone — Wash hands with soap and water, cover the mouth and nose while coughing or sneezing, do not share towels, keep home, food and water clean, remove stagnant water, and stay at home and rest when unwell.
- Easy: Washing hands with soap and water removes pathogens.
- Medium: Boiled water is safe because heat kills the bacteria that cause cholera and typhoid.
- Exam-type: When a village built toilets for every house, fewer children got diarrhoea, because pathogens no longer reached food and water.
Resting at home when unwell helps you recover and also protects others.
Using only one precaution for all diseases. A mask does not stop mosquito-borne malaria; a net does.
Match the route to the block. Memory clue: Air, Water-food, Insects = A-W-I: mask, boil, net.
Spot the difference
| Route | Example disease | Best prevention |
|---|---|---|
| Air | TB, flu | cover mouth and nose, mask |
| Water and food | cholera, typhoid | boiled water, clean food |
| Insects | malaria, dengue | nets, remove stagnant water |
Practice questions
- 1What are vectors?
- 2Which insect spreads malaria?
- 3Which organ does TB mainly affect?
- 4Why should we cover the mouth and nose while sneezing?
- 5Why does boiled water help prevent cholera?
- 6What is a parasite? Give an example.
- 7Many old tyres around a colony hold rainwater. Which step best lowers mosquito-borne disease?
- 8Dengue cases in a clinic: Jan 5, Mar 8, Jun 20, Jul 48, Aug 52, Sep 50, Dec 6. Why do cases peak from July to September?
Show answers (try them yourself first)
- 1Insects such as mosquitoes and houseflies that carry pathogens.
- 2The mosquito.
- 3The lungs.
- 4Tiny droplets can carry pathogens to other people.
- 5Boiling kills the bacteria that cause cholera.
- 6An organism that lives in or on another living being and feeds on it; for example roundworm.
- 7Empty or cover the tyres so water does not stay still.
- 8Rain leaves stagnant water where mosquitoes breed, so dengue rises.
Non-communicable diseases and lifestyle
A canteen sells only fried samosas and sweet drinks, and the children then sit with phones all evening. After some years, doctors find more children with extra weight and high blood sugar. Nobody "caught" it from anyone; it came from daily habits.
Non-communicable diseases (NCDs) are linked to lifestyle, diet and environment. Diseases that last more than 3 months are chronic. Diseases caused by a lack of a nutrient are deficiency diseases.
Key idea 1: Kinds of non-communicable diseases — Deficiency diseases (scurvy, anaemia, goitre), lifestyle diseases (diabetes, obesity, high blood pressure) and environment-linked diseases (asthma from polluted air) are all non-communicable.
- Easy: Diabetes and asthma are chronic non-communicable diseases.
- Medium: Signs of diabetes include frequent urination, excessive thirst, weight loss, tiredness and slow healing of wounds.
- Exam-type: Diabetes often develops from hormonal imbalance, unhealthy eating, inactivity and being overweight.
In the figure: Every column is non-communicable; each has a different cause such as food gap, habits or air.
Key idea 2: Prevention and care — Eat a balanced diet, reduce oil and sugar, exercise regularly, avoid tobacco, sleep well and limit screens. Early diagnosis and continuous care help control the disease. Treatment focuses on managing symptoms and improving quality of life.
- Easy: A balanced diet with regular exercise helps prevent obesity.
- Medium: Kamal Ranadive studied how hormones and viruses are linked to cancer and how tobacco, diet and pollution raise the risk.
- Exam-type: A grandfather who loses weight, feels very thirsty and heals slowly should first be taken to a doctor for tests; early diagnosis helps control the disease.
Most NCDs can be reduced by healthy habits, but they need regular care once they start.
Thinking chronic means very serious or that diabetes can be caught from a patient. Chronic means long-lasting, and diabetes does not spread.
Count three less and three more. Memory clue: LESS oil, sugar, screen; MORE walking, sleep, fruits.
Spot the difference
| Point | Communicable | Non-communicable |
|---|---|---|
| Cause | pathogens | lifestyle, diet, environment |
| Spreads? | yes | no |
| Example | typhoid, flu | diabetes, asthma |
Practice questions
- 1Name one chronic disease.
- 2What do we call a disease that lasts more than 3 months?
- 3Name two deficiency diseases.
- 4Give two signs of diabetes.
- 5Why are NCDs increasing in India?
- 6Why is a deficiency disease non-communicable?
- 7A 45-year-old man has high blood pressure. Suggest two useful changes.
- 8A school canteen sells mostly fried and sugary food. Suggest two changes.
Show answers (try them yourself first)
- 1Asthma (or diabetes).
- 2A chronic disease.
- 3Scurvy and anaemia (or goitre).
- 4Frequent urination and excessive thirst (or tiredness, weight loss).
- 5More processed food, less exercise and longer lives.
- 6It is not caused by a pathogen, so it cannot spread.
- 7Less salt and oil, regular exercise, and no tobacco.
- 8Offer fruits and vegetables, limit sugary drinks and add more play time.
Immunity, vaccines, antibiotics and treatment
A child who had chickenpox once rarely gets it again, and a child who has had a tetanus injection is protected after a cut. The body remembers an enemy it has already met, like a guard who recognises a thief by his face.
Immunity is the natural ability of the body to fight disease. A vaccine trains the immune system using dead, weakened or harmless parts of a germ. Antibiotics are medicines that kill bacteria.
Key idea 1: Vaccines prevent — A vaccine prepares the body before the real germ arrives, so the second meeting gives a quicker and stronger response. Vaccines are preventive, not curative.
- Easy: Vaccines exist for polio, measles, tetanus and hepatitis.
- Medium: Edward Jenner saw that milkmaids who had cowpox did not catch smallpox, and this led to the first vaccine; mass vaccination later removed smallpox from the world.
- Exam-type: In India, teekedaars performed variolation, a mild infection to build immunity against smallpox. When most people are vaccinated, the infection spreads less, so even unvaccinated people are safer.
In the figure: Read from top to bottom: the vaccine trains the body first, so it is ready later.
Key idea 2: Antibiotics treat, but only bacteria — Antibiotics target parts of bacterial cells that human cells do not have, so they do not work against viruses such as cold and flu. Alexander Fleming discovered penicillin in 1928 when a mould stopped bacteria from growing. Using antibiotics wrongly leads to antibiotic resistance.
- Easy: Antibiotics work only against bacterial infections.
- Medium: Use antibiotics only when a doctor prescribes them, in the right dose and for the full time.
- Exam-type: If Rani stops her antibiotic after 2 days because she feels better, some bacteria may survive, multiply and become resistant.
Vaccines are for prevention; antibiotics are for treating bacterial infections only.
Taking antibiotics for a common cold or flu. These are caused by viruses.
One line each. Memory clue: V-P, A-B = Vaccine Prevents, Antibiotic hits Bacteria only.
Spot the difference
| Point | Vaccine | Antibiotic |
|---|---|---|
| Purpose | prevents disease | treats bacterial infection |
| Used | before the disease | when a bacterial infection has occurred |
| Works on viruses? | trains the body against some viruses | no |
Practice questions
- 1What is immunity?
- 2Who developed the first vaccine?
- 3Antibiotics work against which germs?
- 4How does a vaccine protect us?
- 5Why do antibiotics not help in a common cold?
- 6Who discovered penicillin and how?
- 7Why is the immune response stronger when the body meets the same germ a second time?
- 8Saniya says, "Antibiotics cure every infection." What question can Vinita ask to show this is wrong?
Show answers (try them yourself first)
- 1The natural ability of the body to fight diseases.
- 2Edward Jenner (for smallpox).
- 3Bacteria only.
- 4It trains the immune system to recognise and attack harmful germs.
- 5A cold is caused by a virus, and antibiotics do not work against viruses.
- 6Alexander Fleming, who noticed that a mould stopped bacteria from growing.
- 7The immune system has already learnt to recognise that germ.
- 8"Do antibiotics work against viruses such as flu?" They do not; they act only on bacteria.