Class 9
Created by Titas Mallick
Biology Teacher • M.Sc. Botany • B.Ed. • CTET (CBSE) • CISCE Examiner
Created by Titas Mallick
Biology Teacher • M.Sc. Botany • B.Ed. • CTET (CBSE) • CISCE Examiner
A comprehensive guide to the body's defense systems, immunity, and medical aids like vaccines and antibiotics.
To maintain health and combat diseases, the body uses its natural defense systems, supplemented by external medical aids.
The human body has a multi-layered defense system to prevent and fight infections.
This system prevents the entry of pathogens into the body.
If pathogens enter the body, white blood cells (Leukocytes) attack them through Phagocytosis (engulfing bacteria) and inflammation.
Immunity is the ability of the body to resist or destroy pathogens and their toxins.
| Type | Description | Example |
|---|---|---|
| Active | Body produces its own antibodies. | Recovery from Chickenpox |
| Passive | Ready-made antibodies are introduced. | Breast milk (), Anti-tetanus serum |
Vaccination vs. Immunization While often used interchangeably, vaccination is the act of receiving a vaccine, whereas immunization is the process by which the person becomes protected against a disease.
Both are used to kill pathogens, but their application differs:
Chemical substances produced by microorganisms (like fungi or bacteria) that can kill or inhibit the growth of other harmful bacteria.
Synthetic chemicals used to treat bacterial infections by interfering with their metabolism (e.g., Sulfadiazine).
The Story of Penicillin Alexander Fleming noticed that a certain mold inhibited the growth of Staphylococci bacteria in a Petri dish. This accidental observation led to the development of the "wonder drug" penicillin.
Preventive measures like vaccination and maintaining hygiene.
Treating an existing disease using antibiotics, sulfa drugs, or serums.
Complete removal of all microorganisms using heat (autoclaving) or radiation.
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