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The diagram shows the human respiratory system - Junior Cycle Science - Question 9 - 2019
Question 9
The diagram shows the human respiratory system. (a) Complete the table below by matching the words to the letters in the diagram. | Lung | Trachea | Liver | O... show full transcript
Worked Solution & Example Answer:The diagram shows the human respiratory system - Junior Cycle Science - Question 9 - 2019
Step 1
Step 2
Describe what happens in the respiratory system when a person breathes in.
Answer
When a person breathes in, several processes occur:
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Diaphragm contracts: The diaphragm muscle contracts and lowers, creating a vacuum in the chest cavity.
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Intercostal muscles contract: The intercostal muscles between the ribs contract, causing the ribcage to expand upwards and outwards.
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Pressure decreases: The expansion of the chest cavity leads to a decrease in pressure inside the lungs compared to the atmospheric pressure.
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Lungs expand: As a result of the lowered pressure, the lungs expand.
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Air is taken in: Air from outside is drawn into the lungs through the trachea.
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Gas exchange: In the alveoli of the lungs, oxygen from the air enters the blood, while carbon dioxide from the blood leaves and enters the lungs.