Chapter 17: Aids to Health

Local Defense System

The body's first line of defense that prevents entry of pathogens via mechanical barriers, secretions, and white blood cells.

Actions that Help in throwing out germs when entered

Coughing, Sneezing and vomitting.

Protein in skin which prevents entry of germs

Keratin

Mucus

Slimy Secretion of the epithelial lining of various organs.

Germ-killing secretions

Saliva, sweat, tears, and nasal secretions , Hydrochloric acid.

Phagocytes

White blood cells

Phagocytosis

The engulfing of bacteria by white blood cells.

Diapedesis

The process in which a WBC forces its way across the capillary wall.

Merits of Local Defense System

• They start working instantaneously.

• They are not dependent on previous exposure to infections.

• They are effective against a wide range of infectious agents.

Immunity

Resistance to the onset of a disease after infection by harmful agents.

Innate Immunity

The immunity by virtue of genetic constitutional make-up.

Non-specific Innate Immunity

A degree of natural resistance to all infections in general.

Specific Innate Immunity

Natural resistance to a particular kind of germ only.

Acquired Immunity

Resistance to a disease which an individual acquires during his lifetime.

Actively acquired immunity

Immunity due to previous infection or vaccinations.

Passively acquired Immunity

Immunity provided to an individual from an outside source.

This type of immunity is typically gained through maternal antibodies(Natural) or antibody injections, which are antiserums [artificial].

Institutions that are preparing Anti-sera

Haffkine’s Institution (Bombay) and an institution in Kasauli.

Antibodies

Special chemicals formed in the blood which act against the germs or their secretions.

Characteristics of antibodies

• These are proteins (immunoglobulins).

• Produced by a type of specialised lymphocytes on exposure to antigens.

• They bind to specific antigens.

Differences between Active and Passive Immunity

• Active is produced by one’s own body, and passive is received from outside.

• Active is induced by infection, and passive is made by ready-made antibodies.

• Active provides effective and long-lasting protection, while passive offers less effective and temporary protection.

• Active immunity is effective after a certain time, but passive is immediately effective.

Vaccination / Prophylaxis

Introduction of any kind of dead or weakened germs into the body of a living being to develop immunity against the respective disease

Immunisation

Developing resistance to disease-producing germs or their toxins by introducing killed germs or germ substances to induce the production of specific antibodies.

Examples of Vaccines made with killed germs

TAB vaccine (Typhoid), Salk’s vaccine (Poliomyelitis), VAccine for rabies.

Examples of vaccine made by living weakened germs

BCG vaccine (Tuberculosis), Vaccine for measles.

Examples of vaccines made by living, fully poisonous germs

Vaccine for smallpox

Vaccines made by Toxoids

diphtheria and tetanus vaccines.

Toxoids

Inactivated toxins secreted by bacteria which are made harmless by addition of dilute formalin.

DPT

Diphtheria, Pertussis, Tetanus

DT

Diphtheria and Tetanus

BCG

Bacillus of Calmette and Guerin

Toxin

A poisonous substance produced by living cells or organisms that can cause disease.

Antitoxins

Substance produced inside the body in response to the entry of foreign poisonous substance.Antitoxins neutralise toxins to prevent disease.

Antivenins

Substance used to counteract venom from bites or stings of poisonous animals, typically produced by immunizing animals with the venom.

Antiseptics

Mild chemical substance which, when applied on the body, kills germs.

Disinfectants

Strong chemical substances that are applied on spots and places where germs thrive and multiply.

Examples of Antiseptics

Lysol, carbolic acid, iodine, benzoic acid, mercurochrome, boric acid.

Examples of Disinfectants

cresol, phenol, lysol, 40% formalin, lime, DDT, bordeaux mixture.

Antibiotics

Chemical substances produced by some microorganisms that can kill or inhibit the growthof other microorganisms.

First Antibiotic to be discovered

Penicillin, discovered by Alexander Fleming in 1928 from Penicillium chrysogenum.

What is streptomycin obtained from?

Bacteria: Streptomyces griesius

Uses of Antibiotic

• To fight infections.

• Used as food preservatives.

• Treating animal feed.

• Controlling plant pathogens.

Salvarsan

killed germs of syphilis and sleeping sickness but proved poisonous to patient .

Sulphonamides

Synthetic drugs that interfere with the metabolism of bacteria.

Ex- Sulphadiazine and Sulphanilamide