Nota Ringkas: Science Form 3: Chapter 1 : Respiration

RESPIRATION         Definition : a process in breaking of glucose ( food ) with the presence of oxygen to produce

energy / oxidation of food process.          During respiration, humans obtain oxygen which at the same time remove carbon dioxide

and water vapour through the respiratory system.         Oxygen is obtains through breathing.

HUMAN BREATHING MECHANISM

  

STRUCTURE FUNCTIONNASAL CAVITY Air entering from the nostrils is led to the nasal cavity

TRACHEA An airway through which respiratory air travels. The rings of cartilage within its walls keep the trachea open.

BRONCHUS Passage divided from trachea [ singular = bronchus, plural = bronchi ]

BRONCHIOLE A narrow tube inside the lungs that branches off the main air passages bronchi

ALVEOLUS Place where exchange of gases take place

RIB CAGE To protect the lungs and help in breathing mechanism

LUNG A respiratory organ

INTERCOSTAL MUSCLES Antagonistic muscles that help the movement of rib cage

for breathing mechanism

DIAPHRAGM A  muscular membrane that separates the thoracic cavity and the abdominal cavity

BREATHING MECHANISM

INHALATION

= a process when air is force into the lungs

EXHALATION

= a process when air is force out of the lungs

External intercostal muscle contract, while internal intercostal muscle relax

Intercostal muscle External intercostal muscle relax, while internal intercostal muscle

contractMoves upwards and outwards Rib cage Move downwards and inwards

Contract and become flat Diaphragm Relax and become “dome” shape

Volume increase Thoracic cavity Volume decrease

Decrease Air pressure in the lung

Increase

Air from outside enters the lungs

Air movement Air is force out of the lungs

**** You just need to memorize 1 process because the other part is just the OPPOSITE

         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  Exchange of gases  takes place in the alveoli by diffusion.

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

 

   TRANSPORTATION OF OXYGEN

1) Has one cell thick wall (very thin)2) Inside surface has thin film of moisture3) A large number of alveoli4) Has network of blood capillaries surround

each alveoli

1. Oxygen dissolves in the moist lining of the alveolus2. Then, oxygen diffuses into the blood capillaries3. Blood inside the capillaries contains red blood cells that are rich with haemoglobin4. Oxygen combines with haemoglobin to form oxyhaemoglobin5. Oxyhaemoglobin is transported in the blood to heart and then pump to all parts of

the body6. 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 EFFECTSCarbon monoxide Car exhaust Reduces amount of oxygen

in the foodSulphur dioxide Industry, vehicles Damages lung tissuesHydrocarbons Industry, vehicles Cause cancerNitrogen oxide Industry, vehicles Interacts with hydrocarbons

to form hazeHaze Industry, vehicles, open

burningCauses breathing difficulties