NCERT Class 9 Science Chapter 13 WHY DO WE FALL ILL? Notes
NCERT Class 9 Science Chapter 13 WHY DO WE FALL ILL? Notes
13.1 Health and its Failure:
13.1.1 The Significance of 'Health':
- Definition: State of 'being well' implying effective functioning.
- Well-being encompasses physical, mental, and social aspects.
- Example: Grandmother's ability to perform daily tasks signifies good health.
13.1.2 Personal and Community Issues:
- Health reliant on surroundings/environment.
- Social environment crucial for individual health.
- Garbage disposal, drainage maintenance impact health.
- Social environment influences physical environment.
- Availability of work impacts access to food.
- Happy social interactions essential for true health.
13.1.3 Distinctions Between 'Healthy' and 'Disease-Free':
- 'Disease': Disturbed ease, discomfort.
- Disease implies specific cause for discomfort.
- Poor health ≠ absence of disease.
- Example: Different health requirements for a dancer vs. a musician.
13.2 Disease and Its Causes:
13.2.1 What Does Disease Look Like?:
- Disease indicated by changes in organ system functioning.
- Symptoms: Subjective feelings of 'wrong'.
- Signs: Objective indications of disease.
- Laboratory tests aid in diagnosis.
13.2.2 Acute and Chronic Diseases:
- Acute Diseases: Short-lived.
- Example: Common cold.
- Chronic Diseases: Long-lasting.
- Example: Elephantiasis.
13.2.3 Chronic Diseases and Poor Health:
- Chronic diseases have long-term effects on health.
- Acute diseases have minimal impact on general health.
- Chronic diseases impair daily functioning and learning abilities.
- Prolonged poor health associated with chronic diseases.
13.2.4 Causes of Diseases:
- Multifactorial Causes: Diseases have multiple levels of causes.
- Example: Baby with loose motions.
- Infection: Immediate cause.
- Lack of nourishment: Contributory cause due to poor health.
- Poverty: Contributory cause affecting access to clean water.
- Genetic differences: Contributory cause increasing susceptibility.
- Diseases have immediate and contributory causes.
13.2.5 Infectious and Non-Infectious Causes:
- Infectious Causes: Spread by external agents like microbes.
- Diseases spread in the community.
- Non-Infectious Causes: Internal, non-communicable.
- Example: Cancers, high blood pressure, diabetes.
- Different prevention and treatment methods for infectious and non-infectious causes.
13.3 Infectious Diseases:
13.3.1 Infectious Agents:
- Infectious agents classified into viruses, bacteria, fungi, and protozoa.
- Examples of diseases caused by each group.
- Treatment strategies depend on the type of infectious agent.
- 13.3.2 Means of Spread:
- Airborne Transmission: Through sneezing or coughing.
- Example: Common cold, COVID-19.
- Water Transmission: Through contaminated water sources.
- Example: Cholera.
- Sexual Transmission: Through sexual contact.
- Example: Syphilis, AIDS.
- Vector-Borne Transmission: Through intermediary animals (vectors).
- Example: Mosquitoes transmitting malaria.
13.3.3 Organ-Specific and Tissue-Specific Manifestations:
- Disease-causing microbes target specific organs or tissues.
- Manifestations depend on the target tissue/organ.
- General effects include inflammation and fever.
- Severity depends on the number of microbes in the body.
13.3.4 Principles of Treatment:
- Two approaches: Symptom reduction and eradication of the cause.
- Symptom-directed treatment reduces inflammation.
- Microbe eradication involves using drugs targeting specific microbial processes.
- Antibiotics, antiviral drugs, and other medications used based on the type of microbe.
13.3.5 Principles of Prevention:
- Prevention is better than cure.
- General prevention involves avoiding exposure to microbes.
- Specific prevention includes vaccination to stimulate the immune system's memory.
- Childhood immunization programs prevent infectious diseases.
- Access to health measures should be available to all children.
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