Page 218 - IGC BOOK

Superficial Mechanisms

Table 1: Defence mechanism of various body parts.

BODY PART DEFENCES
Respiratory Defences • The hair & wetness of the nose which takes air in upwards
direction.
• The change of direction of the Larynx., Results in dust
above micros deposited in nasal cavity.
• Sneezing & Coughing to remove inhaled & harmful
substance.
• Centrifugal motion of respiratory track. Its design gives
turbulence motion. Which tend throw dust (5 to 10 micron)
outward.
• Tiny hair in the track carry any particles back up to the
larynx. Particles are either spat out or swallowed.
• White blood cells in alveoli attract foreign body by
ingesting them or surrounding them.
• Fibrosis – although scarring of the lungs will inhibit their
capacity.
• Dust particles 0.5 to 7 micros & fiber less than 5 micron
suspended in the air & exhale from lungs. Some will remain
& attached to the lungs & cause chronic disease.
• Substance enter the blood stream from respiratory system
will eventually reach the liver. Liver can deal with many toxic
substances.

Ingestion Defences • A harmful ingested substance has to survive the acid in the
stomach & the various enzyme and bacteria with in
digestive track. Some harmful substance cause immediate
reaction causes the defence mechanism of vomiting and
diarrhea.
Skin Defences • Epidermis provides protection on outer layer & dermis
control member of defence.
• Sebum secretions provide protection against water, weak
acid & alkalis. Prevent from skin drying.
• Melanin protection against Ultra Violet light.
• Blister, rashes & inflammation – Reaction to damage or
attack & result from increase flow of blood.

ENSIGN| Unit IG2 – Element 7 – Chemical and Biological 13
Agents