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Breathing is the process of inhaling and exhaling air by the lungs .
The human respiratory system is the system in the body that helps us to breathe.
Diagram below shows the structure of human respiratory system
Breathing Mechanism
Breathing Mechanism
The direction of air from the nose to the lungs is shown in Figure above
Inhalation
Inhalation
When you inhale,
intercostal muscles contract and pull the rib cage upwards and outwards as shown in diagram above.
diaphragm muscles contract and pull the diaphragm to descend and become flat.
movements of the rib cage and diaphragm make the thoracic cavity bigger and cause air pressure in the thoracic cavity to decrease.
the higher air pressure outside forces air to enter the lungs as shown in diagram (b).
Exhalation
Exhalation
When you exhale,
intercostal muscles relax and the rib cage moves downwards and inwards as shown in diagram above.
diaphragm muscles relax and curve upwards.
movements of the rib cage and diaphragm make the thoracic cavity smaller and cause the air pressure in the thoracic cavity to increase.
the higher air pressure in the lungs pushes the air out as shown in diagram (b).
Experiment 2.1
Experiment 2.1
To study the difference in the percentage of oxygen in inhaled and exhaled air.
To study the difference in concentration of carbon dioxide in inhaled and exhaled air
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