Science Form 3 Chapter 1-Respiration

Short Note Of Science
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1.Respiratory syst. made up of...


2.Breathing mechanism

Inhalation:-thoraric cavity-bigger
-air pressure in lung-lowered
-air force into lungs
Exhalation:-thoraric cavity-smaller
air pressure in lung-increased
-air forced out of lung
3.Transport of oxygen

-oxygen dissolve in alveolus,then diffuse into
blood capillaries
-the blood contain red blood cell which rich with haemoglobin
-the blood leave lung and carried to the heart,then disstribute to all pats of body

4.Effects of harmful substances:
a)Cigarette smoke

contain:tar-cause lung cancer
nicotine-cause addiction to smoking
carbon monoxide-reduce oxy. in blood

b)car exhaust
contain: carbon monoxide-reduce oxy. in blood

c)Industry and vehicles

contain:sulphur dioxide-damage lung tissues
hydrocarbons-cause cancer
nitrogen oxide-interacts with
hydrocarbons to form haze
5.Diseases that affect respiratory system

-bacteria,virus&micoorganisms produce toxins in human body which cause illness
-virus-cause influenza and whooping cough or
-asbestos dust is a carcinogen which cause lung cancer
9.Ways to improve quality of air

a)stop smoking
b)use air cleaning system to dissolve toxic gases
like sulphur dioxide in water before released
into atmosphere
c)install catalyst convertors on vehicle exhaust pipe to reduce dangerous gases like carbon monoxide

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