CBSE Class 8 Annual Assessment

Chapter 3: Health: The Ultimate Treasure

Summary

This chapter treats health as far more than the absence of disease. Following the World Health Organization, it defines health as a state of complete physical, mental, and social well-being. Staying healthy depends on lifestyle and environment: eating a balanced diet, exercising, sleeping well, limiting screen time, keeping surroundings clean, and avoiding harmful substances like tobacco and alcohol. The chapter distinguishes symptoms (what we feel, such as pain) from signs (what can be seen or measured, such as fever). Diseases are grouped as non-communicable, which are linked to lifestyle, diet, or environment and do not spread (such as diabetes, asthma, and cancer), and communicable, caused by pathogens and able to spread (such as typhoid, dengue, and influenza). Pathogens spread through air, water, food, direct contact, and vectors like mosquitoes. The body fights disease using its immune system. Vaccines provide acquired immunity by training the immune system with weakened, dead, or harmless parts of a germ; Edward Jenner developed the first vaccine against smallpox, and India long practised variolation. Antibiotics treat bacterial infections only, and their misuse causes antibiotic resistance, so they must be used wisely. Prevention through hygiene, sanitation, balanced diet, and timely vaccination is emphasised.

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