Mechanics of Breathing
-If gas molecules are far apart, then the pressure will
lower
-If gas molecules are closer, then the pressure will
rise
Inspiration: the movement of air flowing into the
lungs
Expiration: the movement of air flowing out of the
lungs
lower
-If gas molecules are closer, then the pressure will
rise
Inspiration: the movement of air flowing into the
lungs
Expiration: the movement of air flowing out of the
lungs
INSPIRATION (INHALATION)
When does the size of the thoracic cavity increase?
1. When the DIAPHRAGM and EXTERNAL INTERCOSTALS (inspiratory muscles) contract because the diaphragm flattens out and moves inferiorly when it contracts and, due to the contraction of the external intercostals, it lifts the rib cage and thrusts the sternum forward.
2. The LUNGS expand to the new size of the thoracic cavity because the lungs and thoracic walls are tightly attached.
Due to the increase in the size of the lungs, the INTRAPULMONARY VOLUME (volume within the lungs)
increases, the gases spread out to fill the large space
When there is a decrease in gas pressure in the lungs, then the air is sucked into the lungs by a partial vacuum (pressure less than atmospheric pressure) and continues until the intrapulmonary volume = atmospheric volume
1. When the DIAPHRAGM and EXTERNAL INTERCOSTALS (inspiratory muscles) contract because the diaphragm flattens out and moves inferiorly when it contracts and, due to the contraction of the external intercostals, it lifts the rib cage and thrusts the sternum forward.
2. The LUNGS expand to the new size of the thoracic cavity because the lungs and thoracic walls are tightly attached.
Due to the increase in the size of the lungs, the INTRAPULMONARY VOLUME (volume within the lungs)
increases, the gases spread out to fill the large space
When there is a decrease in gas pressure in the lungs, then the air is sucked into the lungs by a partial vacuum (pressure less than atmospheric pressure) and continues until the intrapulmonary volume = atmospheric volume
EXPIRATION (EXHALATION)
*Depends on natural elasticity of the lungs than on muscle contraction.
*The normal pressure within the pleural space (INTERPLEURAL PRESSURE) is ALWAYS negative and a major factor for preventing the collapse of the lungs.
*The normal pressure within the pleural space (INTERPLEURAL PRESSURE) is ALWAYS negative and a major factor for preventing the collapse of the lungs.