Respiratory physiology HWH

Respiratory physiology HWH - Forces of breathing...

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Forces of breathing Respiration results from forces that are applied to and by different parts of the respiratory apparatus. Both passive and active forces are operating during breathing. Passive force is inherent to muscles and other tissues Active force is applied voluntarily.
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Passive force Results from natural recoil of muscles, cartilages, ligaments and lung tissue gravity These cause the respiratory apparatus to behave like a spring which always tends to recoil to its resting length. The direction and magnitude of passive force depends on the amount of air within the lungs and whether the tissues are stretched or compressed (i.e., deformed). The extent to which the tissues are deformed determines the magnitude of the passive recoil force that is generated.
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Figure 2.4
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Active force Arises from the action of muscles of the chest wall. The direction and magnitude of this force depends on the amount of air in the lungs. The contribution of an individual muscle will be influenced by the actions of other muscles, the status of different parts of the chest wall, and the particular activity being performed.
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Inspiration During inspiration, alveolar pressure drops below atmospheric pressure. The extent to which it drops depends on the speed and extent of lung enlargement. Since airflow is proportional to the pressure difference between the lungs and atmosphere, changes in flow follow those is atmospheric pressure. Quiet Inspiration At rest, we take air into our lungs between 12-20 times/minute. Although rather automatic , there must be active muscle contraction in order to enlarge the thorax. Forced Inspiration
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Respiratory physiology HWH - Forces of breathing...

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