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Diseases and First Aid
ICSE Class 8 Biology • Chapter 8 (Detailed Master Notes)
Chapter Overview
Health is not merely the absence of disease, but a state of complete physical, mental, and social well-being. This chapter covers the classification of diseases and fundamental first aid principles to follow before medical help arrives.
8.1 Types of Diseases
A disease is an abnormal condition that affects the structure or function of a living organism.
| Communicable Diseases (Infectious) | Non-Communicable Diseases |
|---|---|
| Caused by microscopic germs, pathogens, or vectors. | Caused by poor diet, bad lifestyle, bad genes, or aging. |
| Easily spreads from a sick person to a healthy person (e.g., via coughing). | Strictly confined to the patient. Cannot spread to others at all. |
| Examples: Tuberculosis (TB), Malaria, Cholera, COVID-19. | Examples: Scurvy (Vitamin C lack), Diabetes, Heart disease. |
8.2 Vectors: Disease Carriers
Vector: A living organism (usually an insect) that carries a disease-causing pathogen from a sick person to a healthy person, without getting sick itself.
- Housefly: Sits on garbage, picks up bacteria on its hairy legs, and then lands on uncovered human food. Causes Cholera and Typhoid.
- Female Anopheles Mosquito: Bites a sick person, sucks up the parasite in blood, and injects it into a healthy person. Causes strict Malaria.
- Aedes Mosquito: Spreads Dengue fever. It breeds in clean, stagnant water.
AI Image Prompt: A colorful graphic showing a mosquito sucking blood from a human arm. Show tiny glowing green germs traveling from the insect's needle-like mouth directly into the human bloodstream.
8.3 Immunity and Vaccination
Our body fights diseases using White Blood Cells. Once exposed to a virus, the body creates specific Antibodies. These antibodies remember the germ and destroy it instantly if it ever attacks again. This is called Immunity.
Vaccination: A medical process using a vaccine. A vaccine contains heavily weakened or entirely dead germs. When injected into a healthy child, the immune system harmlessly fights them and learns how to produce the exact antibodies. If the real, dangerous disease ever attacks, the body is already prepared.
8.4 First Aid Basics
First aid is the immediate, temporary medical care given to a victim of an accident before a doctor arrives.
Common First Aid Procedures:
- Burns: Immediately hold the burnt area under cool running water for 10-15 minutes. Never apply ice, butter, or oil directly. Cover lightly with a sterile gauze pad.
- Bleeding Cuts: Wash the cut with clean water to remove dirt. Apply firm, direct pressure on the wound using a clean cloth to stop bleeding. Apply an antiseptic cream.
- Animal Bites (Dog): Wash the affected area thoroughly with strong soap and running water to remove dog saliva (preventing deadly Rabies). Take the victim to a hospital immediately for Anti-Rabies injections.
- Fainting: Make the person lie completely flat on their back. Elevate their legs slightly. This forces blood to easily flow back to the brain.
Q1. Why are diseases like scurvy and rickets classified strictly as non-communicable diseases?
Answer: Scurvy represents a specific deficiency of Vitamin C, and Rickets is caused completely by a lack of Vitamin D in diet. Because they are caused purely by poor nutrition and not explicitly by a pathogen or infectious germ, they physically cannot spread from a sick person to a healthy individual.
Q2. State the central principle of First Aid for treating heavy bleeding.
Answer: The primary vital goal is to stop blood loss. Apply steady, strong, direct physical pressure cleanly on the wound utilizing a thick sterile medical dressing. If the bleeding persists, cleanly elevate the injured limb higher than the heart level to slow the arterial blood flow securely.