Respiratory Cycle / Quiet breath: When the respiratory muscles are relaxed and there is no respiratory movement
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When the respiratory muscles are relaxed and there is no respiratory movement...

The inspiratory muscles such as the diaphragm are relaxed and the lung volume (within a quiet breath) is at its minimum. The inward elasticity of the lungs and the outward elasticity of the chest wall are balanced. The pleural pressure is negative. The pressure inside the lungs (alveolar pressure) is equal to the atmospheric pressure and there is no gas (air) flow. Since the lung volume (within a quiet breath) is at its minimum, the lung elastic force and the pleural pressure are also at their minimum.

Achievement Quiz
When the respiratory muscles are relaxed and there is no respiratory movement, the diaphragm is 1 [ A contracting / B relaxed ].
When the respiratory muscles are relaxed and there is no respiratory movement, the lung volume is 2 [ A at its minimum / B increasing from its minimum to its maximum / C at its maximum / D decreasing from its maximum to its minimum ] (within a quiet breath).
When the respiratory muscles are relaxed and there is no respiratory movement, the inward elastic force of the lungs is 3 [ A at its minimum / B increasing from its minimum to its maximum / C at its maximum / D decreasing from its maximum to its minimum ] (within a quiet breath).
When the respiratory muscles are relaxed and there is no respiratory movement, 4 [ A gas (air) flows in / B there is no gas flow / C gas flows out ].
When the respiratory muscles are relaxed and there is no respiratory movement, the pressure inside the lungs (alveolar pressure) is 5 [ A negative compared / B equal / C positive compared ] to the atmospheric pressure.
When the respiratory muscles are relaxed and there is no respiratory movement, the negative pleural pressure is 6 [ A at its minimum / B increasing from its minimum to its maximum / C at its maximum / D decreasing from its maximum to its minimum ] (within a quiet breath).
Answer
1 [ B relaxed ]
2 [ A at its minimum ]
3 [ A at its minimum ]
4 [ B there is no gas flow ]
5 [ B equal ]
6 [ A at its minimum ]
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