NCERT BIOLOGY · UNIT VIII
HUMAN HEALTH
AND DISEASE
, Table of Contents
1. What is Health & Disease? Intro
2. Common Diseases in Humans Bacterial · Viral · Protozoan · Helminth · Fungal
3. Prevention & Control of Infectious Diseases Hygiene, Vectors, Vaccines
4. Immunity Innate vs Acquired
5. Antibody Structure & Types Ig Classes
6. Active & Passive Immunity + Vaccination
7. Allergy & Autoimmunity Disorders of Immunity
8. Lymphoid Organs Immune System Anatomy
9. AIDS HIV Structure, Life Cycle, Prevention
10. Cancer Causes, Detection, Treatment
11. Drugs & Alcohol Abuse Opioids, Cannabinoids, Tobacco
12. Quick Revision — Summary Sheet Mind Maps & Tables
, 1⃣ What is Health and Disease?
For centuries, health was thought of as a balance of body "humors" — an idea from early Greek physicians like Hippocrates and the Indian
Ayurveda system. This was disproved once scientific tools like the thermometer appeared. William Harvey's discovery of blood circulation
(through experiment, not just reflection) marked the shift toward evidence-based medicine.
Modern Definition of Health
Health is NOT merely the "absence of disease." WHO defines it as: "a state of complete physical, mental and social well-being."
Health is influenced by three main factors
1 Genetic disorders — deficiencies present at birth or inherited from parents.
2 Infections — caused by disease-causing organisms (pathogens).
3 Lifestyle — food, water, rest, exercise, and personal habits.
Why does good health matter to society?
A healthy population is more efficient at work → higher productivity → economic prosperity. Good health also increases longevity and
reduces infant & maternal mortality.
How is Disease Classified?
DISEASE
Congenital Diseases Acquired Diseases
Present since birth; due to developmental defects or metabolic Develop after birth — divided into Infectious (communicable,
disorders. spread person-to-person, e.g., AIDS) and Non-infectious (non-
communicable, e.g., Cancer — the major cause of death among
these).
Pathogen
A pathogen is any organism (bacteria, virus, fungi, protozoan, helminth) that causes disease. Pathogens must adapt to the host's
internal environment — e.g., gut pathogens must survive stomach acid and digestive enzymes.
HUMAN HEALTH
AND DISEASE
, Table of Contents
1. What is Health & Disease? Intro
2. Common Diseases in Humans Bacterial · Viral · Protozoan · Helminth · Fungal
3. Prevention & Control of Infectious Diseases Hygiene, Vectors, Vaccines
4. Immunity Innate vs Acquired
5. Antibody Structure & Types Ig Classes
6. Active & Passive Immunity + Vaccination
7. Allergy & Autoimmunity Disorders of Immunity
8. Lymphoid Organs Immune System Anatomy
9. AIDS HIV Structure, Life Cycle, Prevention
10. Cancer Causes, Detection, Treatment
11. Drugs & Alcohol Abuse Opioids, Cannabinoids, Tobacco
12. Quick Revision — Summary Sheet Mind Maps & Tables
, 1⃣ What is Health and Disease?
For centuries, health was thought of as a balance of body "humors" — an idea from early Greek physicians like Hippocrates and the Indian
Ayurveda system. This was disproved once scientific tools like the thermometer appeared. William Harvey's discovery of blood circulation
(through experiment, not just reflection) marked the shift toward evidence-based medicine.
Modern Definition of Health
Health is NOT merely the "absence of disease." WHO defines it as: "a state of complete physical, mental and social well-being."
Health is influenced by three main factors
1 Genetic disorders — deficiencies present at birth or inherited from parents.
2 Infections — caused by disease-causing organisms (pathogens).
3 Lifestyle — food, water, rest, exercise, and personal habits.
Why does good health matter to society?
A healthy population is more efficient at work → higher productivity → economic prosperity. Good health also increases longevity and
reduces infant & maternal mortality.
How is Disease Classified?
DISEASE
Congenital Diseases Acquired Diseases
Present since birth; due to developmental defects or metabolic Develop after birth — divided into Infectious (communicable,
disorders. spread person-to-person, e.g., AIDS) and Non-infectious (non-
communicable, e.g., Cancer — the major cause of death among
these).
Pathogen
A pathogen is any organism (bacteria, virus, fungi, protozoan, helminth) that causes disease. Pathogens must adapt to the host's
internal environment — e.g., gut pathogens must survive stomach acid and digestive enzymes.
