Why Do we Fall ill Class 9 Notes CBSE Science Chapter 13

Why Do we Fall ill Class 9 Notes CBSE Science Chapter 13

CBSE NCERT Based Class 9 Science Revision is your ultimate guide to Chapter 13, Why Do we Fall ill, is a must-read for all students. And guess what? These notes are part of the Revision Notes for Class! 

Our Science Notes provide a comprehensive overview of all the key concepts and topics covered in the NCERT TextBooks Class 9th Revision Science Notes . This Chapter Notes is your one-stop-shop for all things related to pathogens, air-borne diseases caused by bacteria and viruses (think common cold, influenza, measles, tuberculosis), food and water-borne illnesses, sedentary lifestyle practices, and genetic factors. 

So, whether you're looking to brush up on your knowledge or dive deeper into the subject matter, our Science Notes have got you covered. Get ready to ace your exams and impress your teachers with your newfound expertise!

Well prepared CBSE Class 9th Chapter Wise Science Notes will guidance students understand the topics ,concepts and themes covered in all the chapters of Ncert Text book of 9th 

Cbse Class 10th Health 

why Do we Fall ill Class 9 Notes CBSE Science Chapter

It is a state of being well so that one can perform Physical, social and mental functions properly. for Example - we say a person is healthy if they can. perform their day to day tasks very well.

Why Do we Fall ill Class

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Significance of Health

(i) It increases our working efficiency & helps us to perform various activity.

(ii) It helps us to cope up with the Social & mental pressure without much difficulty. 

Is health dependent on personal and social issues ?
Yes, Personal and Community health are supplementary to each other. • we protect ourselves by keeping our for this, we also require a good healthy and in our Surroundings. body clean. environment so, both personal and community health are inter-related. Disease and its Causes &

• Disease Ary condition that disturbs or modifies the normal functioning of our body is called disease. 

what does disease look like ? When a person is affected by a disease either the
functioning or appearance of one or more systems will change. 
• These changes give rise to symptoms and signs of disease.

Symptoms of diseases are the indications that we feel as being , such as cold, headache, loose motion ete.

Causes of Diseases pathogens like virus, bacteria, fungi protozoans of worms. Poor health and under nourishment

Hereditary and genetic disorder. Environmental pollution (air, water etc.)

Types of Diseases &

(1) Acute diseases

 which last for only very Short period of time and affect body suddenly. Eg cold, cough, typhoid etc.

2) chronic diseases: 

The diseases which last for a long time, even as much as a Life time are called chronic diseases Eg. Diabetes, tuberculosis, etc. (f) Infectious Disease & The diseases which spread due to infection by micro-organisms are called infectious disease. It is Communicated from diseased Person to healthy, Person. It is transferred through virus, bacteria, fungi etc -

(N) Non-infectious Diseases 

 The disease which does not spread by contact between infected and healthy person through air and water is called non-infectious disease.Eg. Arthritis, Diabetes, heart diseases ele (v)

 Congenital diseases: 

The diseases present since birth, caused due to genetic abnormalities or defective development of embryo. e.g- haemophilic. 

Difference between Infections & Non-infectious disease

Non-infectious/Non- Communicable
These diseases not spread from one person to the

2. These coil bedd deficiency, cancer, degradation, injury or metabolic diseases

3. May be chronic cut 4. for common cold, TB et Infectious Agents 

3. Primary by chronic: 

1. These disease spend from one post another Throw due to pathogens like viruses, bacteria

The pathogens or microbes that cause infectious diseases are also called as infectious Agents-

characteristics of infectious agents- Viruses live inside the host body. Bacteria do not generally live inside the host body. Virus, bacteria and fungi multiply quickly.

Worms do not multiply quickly. 

Epidemic diseases 200

Some infectious diseases that develop and spread rapidly to many people in a community are called epidemic diseases.

e.g. Corona virus.

Infectious agent Virus

Common cold, influenza, dengue fever, AIDS

Typhoid fever, cholera.

tuberculosis, anthrax

Many common

Infectious disease



Protozoan Worms


Malaria, kala azar worm infections,


Means of Spread of Infectious sneezing and coughing, the microbes Spread into air and enter into the body of a healthy person, like common cold, tuberculosis etc.

•Through water: The microbes enter into our body by drinking /eating polluted and contaminated water/ food Like cholera, amoebic dysentery etc.

• Vectors & कुछ Infected प्राणी जैसे Dog, cat, Monkey mosquito (female mosquito) spread the diseases to a healthy person when they bite them like Rabies, malaria, dengue, yellow fever etc..

•Through Sexual Contact (STD) & AIDS Spread by sexuall Contact with infected person. AIDS virus can also spread through blood transfusion and from the mother to her child during pregnancy and through breast footing.

AIDS (Acquired Immune Deficiency Syndrome) :

Couses - AIDS is caused by a virus called HIV

deficiency Virus) Method of transmission of AIDS- The transmission of AIDS from an infected to a healthy. person takes place through Sexual Contact blood transfusion use of infected needle or blade from mother to her baby! foetus.

Prevention -

 Avoid transfusion of infected blood Always use disposable needle and syringe. Avoid Sexual Contact with unknown person.

 Disease causing microbes enter the body by different means and goes to different organs and tissues.

(1) Microbes which enter through the nose are likely to go to lungs. (Bacteria which cause tuberculosis) (D Microbes which enter through the mouth are Likely to stay in the gut bacteria which caused typhoid) (i) Virus which causes ADS enter the body through sexual organs during serum contact and spread through lymph to all parts of the body and damages immune system. () Virus which causes brain fever enters through. mosquito bite and goes and infects the brain Principles of Treatment &

Treatment of infectious disease, consists of two steps & (1) To reduce the effects of disease 8 This can be done by taking medicines to bring down the effects of disease Like fever, pain ete. and by taking bed rest to conserve our energy. U To Kill the microbes &

This can be done by taking suitable antibiotics and drugs which kills the microbes and disease is cured.

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