Monday, 16 April 2012

Nota Ringkas: Science Form 3: Chapter 1: Respiration



RESPIRATION 

· Pathway taken by air during inhalation:
Nostril ---> Nasal cavity--> Trachea--->Bronchus---->Bronchiole--->Alveolus

· Pathway taken by air during exhalation:

Alveolus

--->
Bronchiole
-->
Bronchus
--->
Trachea
---->
Nasal cavity
--->

Nostril


Transport of oxygen in human body
v Exchange of gases takes place in the alveoli by diffusion.

v Characteristics of alveoli that help exchange of gases to take place effectively:


Ø Has one-cell thick wall ( very thin)
Ø Inside surface has thin film of moisture
Ø Huge number of alveoli
Ø Network of blood capillaries surround each alveoli


TRANSPORTATION OF OXYGEN
  1. Oxygen dissolves in the moist lining of the alveolus
  2. Then, oxygen diffuses into the blood capillaries
  3. Blood inside the capillaries contains red blood cells that are rich with haemoglobin
  4. Oxygen combines with haemoglobin to form oxyhaemoglobin
  5. Oxyhaemoglobin is transported in the blood to heart and then pump to all parts of the body
  6. Oxyhaemoglobin breaks down, oxygen diffuses into the cells, at the same time carbon dioxide diffuses into the blood
EFFECTS OF OTHER AIR POLLUTANTS
CHEMICAL SUBSTANCE
SOURCES
DAMAGING EFFECTS
Carbon monoxide
Car exhaust
Reduces amount of oxygen in the food
Sulphur dioxide
Industry, vehicles
Damages lung tissues
Hydrocarbons
Industry, vehicles
Cause cancer
Nitrogen oxide
Industry, vehicles
Interacts with hydrocarbons to form haze
Haze
Industry, vehicles, open burning
Causes breathing difficulties

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