Main topics covered in this part of CBSE Class 9 Science, Why Do We Fall Ill: Chapter Notes, are:
- Health
- *** and its Types
- Causes of ***
- Antibiotics
- Principle of Treatment
- Principles of Prevention
Key notes for Chapter - Why Do We Fall Ill, are:
Health
Health is a state of complete physical, mental and social wellbeing.
Disease
Any disturbance in the structure or function of any organ or part of body.
It may be caused due to the ** of pathogens (virus, bacteria), lack of nutritious diet/balanced diet and lack of public health services.
Types of Disease
**** are basically of two types. They are:
(i) Acute Disease
The ** which lasts for only a short of time is called Acute **.
For example: Influenza (Flu) , Common cold, etc.
(ii) Chronic ****: The which lasts for long ** of time is called Chronic ***
For example: TB, **, etc.
Difference between Acute **** & Chronic Disease*
| S. No. | Acute Disease | Chronic Disease |
| 1. | They are short duration ** | They are long lasting ** |
| 2. | Patient recovers completely after the cure | Patient does not recover completely |
| 3. | There is no loss of weight or feeling of tiredness afterward | There is often loss of weight of feeling of tiredness |
| 4. | There is short duration loss of work and efficiency | There is a prolonged loss of work and efficiency |
Causes of **:**
Causes of **** are explained below:
Immediate and Contributory Cause
- Immediate cause: The organisms that enter our body and causes *** is called immediate cause. For example, virus, bacteria, protozoa etc.
- Contributory cause: The secondary factors which led these organisms enter our body are called as contributory cause. For example, ***** water, contaminated food, improper ourishment, poor standard of living etc.
Infectious and Non-infectious Cause
Infectious causes: They include the agents like microbes or micro-organisms as the immediate causes which spread the *** from an infected person to a healthy person.
Non-infectious causes: The ** which does not spread by contact between infected and healthy person through air and water, is called non-infectious **.
Infectious and Non-infectious Diseases
Infectious **: The ** which spread due to infection by micro-organisms are called infectious ****.
When a *** causing organism enters our body it causes infection, it multiplies and grows in the body called host and micro-organisms multiplies in the host body.
For Example: Tuberculosis, tetanus, Common cold, AIDS, etc.
Non-infectious **: The **** which does not spread by contact between infected and healthy person through air and water, is called non-infectious **.
For example: **, genetic abnormalities, high blood pressure, etc.
Means of Spreading Infectious **:**
| S. No. | Type of Disease | Example |
| 1. | Air born **** | Common cold, influenza, measles, tuberculosis. |
| 2. | Water born **** | Cholera, typhoid, hepatitis. |
| 3. | ** **** | AIDS, ****. |
| 4. | Animal born *** | Rabbis. |
