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level: 6.7 The mechanism of breathing

Questions and Answers List

level questions: 6.7 The mechanism of breathing

QuestionAnswer
The diaphragm- Sheet of muscle that separates the thorax from the abdomen
The intercostal muscles- Lie between the ribs - Two set of intercostal muscle: Internal + external
Internal intercostal muscles- Contraction leads to expiration
External intercostal muscles- Contraction leads to inspiration
Ventilation- Breathing in and out
Thoracic cavity- Space where the lungs are
Lung pressure- Air will always move from a region of higher pressure to a region of lower pressure - Down pressure gradient - Air moves down the trachea into the lungs
Inspiration- The external intercostal + diaphragm muscles contract - The ribcage moves up + out - Diaphragm flattens, increasing volume of thoracic cavity - Pressure decreases - Active process, requires energy
Expiration- The external intercostal + diaphragm muscles relax - The ribcage moves down + in - Diaphragm curves again, decreasing volume of thoracic cavity - Pressure increases - Air forced down pressure gradient out of lungs - Passive process, no energy needed
Forced expiratione.g. blowing candles on cake - External intercostal muscles relax - Internal intercostal muscles contract - Pulling ribcage further down + in - During this, movement of the two set of i.ms is called antagonistic (opposite)