Why Do we Fall ill Class 9 Notes Science Chapter 13

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

Introduction

Health is a state of complete physical, mental and social well-being.

Basic conditions for good health:

• Proper balanced and nutritious diet.
• Personal hygiene.
• Clean environment and surroundings.
• Healthy air, no pollution in the surrounding.
• Regular exercise.
• Proper rest.
• Good standard of living and economic status.

Disease: when the body is not at ease, i.e., comfortable, it is said to have a disease.
When there is a disease, the functioning or appearance of one or more systems of the body changes.
Depending on the duration—the disease is classified as acute or chronic.

Acute disease: Diseases that last for only a short period of time, e.g., headache, common cold, etc.

Chronic disease: Diseases that last for a long time’ are chronic, e.g., elephantiasis, tuberculosis, etc.

Causes of diseases: Immediate cause and contributory cause.

Immediate cause: The organisms that enter our body and causes the disease is called immediate cause—for example, viruses, bacteria, protozoa, etc.

Contributory cause: The secondary factors which led these organisms to enter our body are called contributory causes. For example, dirty water, unclear
surroundings, contaminated food, improper nourishment, poverty, poor standard of living, etc.
Diseases may be due to infectious and non-infectious causes.

(a) Infectious causes: Diseases where microbes are the immediate causes, are called infections diseases. The infection spreads from one person to another.

(b) Non-infectious causes: Some diseases that do not spread in the community but remain internal are called non-infectious diseases—for example, cancer, genetic abnormalities, high blood pressure, etc.

Infectious diseases (Communicable diseases): When a disease-causing organism enters our body, it causes infection, it multiplies and grows in the body called the host, and micro-organisms multiply in the host body.

Infectious diseases spread through:

• Air: Causes airborne diseases due to bacteria, viruses, e.g., common cold, influenza, measles, tuberculosis.
• Food and water: Is caused due to contaminated food and water that contains bacteria, viruses, worms, etc. Examples are cholera, typhoid, and hepatitis.
• Contact: Many diseases are spread by contact between an infected person with a healthy person. Examples are fungal infections, scabies, etc.
  AIDS and syphilis spread due to sexual contact.
• Body fluids: Body fluids like blood, semen, and mother milk, when infected, can also cause disease—for example, AIDS.

Antibiotics: These chemicals (medicine, drugs) block biochemical pathways important for bacteria. They are used for diseases caused by bacteria.

Inflammation: It is called inflammation when an active immune system releases many cells to the affected tissue to heat off the disease-causing microbes. Due to inflammation, local effects caused to the body are swelling, pain, fever, and redness.

Principles of treatment

• To reduce the effects of the diseases.
• To kill the cause of the disease, i.e., to kill the microbes like bacteria, fungi, and protozoa.

Principles of Prevention

• General method
• Specific method

General ways of preventing infections relate to preventing exposure.

Prevention of exposure can be done in the following ways:

• Cover your nose and mouth while coughing for airborne infections—valid -visiting a public place.
• For water-borne infections- Drink, clean, and boil thinking water.
• For vector-borne infections, Keep the surroundings clean, and do not keep any puddle of water open in the surroundings as it allows the breeding of mosquitoes.
• A self immune system can (fight off and kill microbes when it enters our body.
• Availability of proper and sufficient -food for everyone.

Specific ways: 1% (giving vaccines, a childhood immunization given to the children for (preventing infectious diseases.

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