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Respiratory system 2 (Inspiration (Stimulation of diaphragm by phrenic…
Respiratory system 2
Inspiration
Stimulation of diaphragm by phrenic nerves changes the volume within lungs. This causes a downward contraction and stimulation of external intercostal muscles to raise the ribs
Chest cavity expand and parietal pleura clings to it. Visceral pleura attached to the lungs is carried along, sue to intrapleural pressure (lungs expand)
Another force that expands the lungs is warming of inhaled air. As inhaled air warms, it helps to expand the lungs
Pressure and flow
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Barometric pressure drives respiration. Air moves into the lungs because volume of lungs increased (Boyle's law), dropping intrapulmonary pressure.
During exhalation, intrapulmonary pressure > atmospheric pressure, so air leaves the lungs
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Expiration
Requires muscular effort to inhale, burn calories/ ATP. Whereas exhalation is passive
It is due to the relaxation of diaphragm and external intercostal muscles return to their original position (elastic recoil). Air pressure is greater inside the lungs (small volume) than outside the body, and air leaves the lungs
To force a deeper expiration, the intercostal muscles contract and depress the ribs
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Alveolar Ventilation: Dead air that cannot exchange gas with blood and in conducting division is called anatomic dead space. Alveolar ventilation rate gives the most directly relevant measure of the body's ability to get oxygen to tissues
Non-respiratory air movements: yawning, sneezing, coughing, laughing, crying and sneezing (irritants in nasal cavity) and coughing (irritants in the lower respiratory tract)