Difference between revisions of "Ventilation - Anatomy & Physiology"
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==Introduction== | ==Introduction== | ||
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==Inspiration== | ==Inspiration== | ||
| − | During Inspiration, the pressure within the [[Pleural Cavity and Membranes - Anatomy & Physiology|pleural cavity]] drops to less than the pressure of the external environment. This is achieved by increasing the [[Lungs - Anatomy & Physiology|lung]] volume, brought about by the | + | During Inspiration, the pressure within the [[Pleural Cavity and Membranes - Anatomy & Physiology|pleural cavity]] drops to less than the pressure of the external environment. This is achieved by increasing the [[Lungs - Anatomy & Physiology|lung]] volume, brought about by the Inspiratory Muscles. The [[Diaphragm - Anatomy & Physiology|diaphragm]] contracts, causing the dome to flatten and move caudally. The [[Ribs and Sternum - Anatomy & Physiology#Thoracic Musculature|external intercostal muscles]] contract, causing the [[Ribs and Sternum - Anatomy & Physiology|ribs]] to be pulled outwards cranially. |
==Expiration== | ==Expiration== | ||
| − | During | + | During Expiration, the pressure within the [[Pleural Cavity and Membranes - Anatomy & Physiology|pleural cavity]] increases to greater than that of the external environment, in order to expel air from the [[Lungs - Anatomy & Physiology|lungs]]. This is achieved by decreasing the lung volume, and is brought about by relaxation of inspiratory muscles. The dome of the [[Diaphragm - Anatomy & Physiology|diaphragm]] is pushed back by the intrathoracic pressure and the [[Ribs and Sternum - Anatomy & Physiology|ribs]] recoil back to their original position. |
==Species Differences== | ==Species Differences== | ||
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{{citation|initiallast = Budras|initialfirst = K.D|2last = McCarthy|2first = P.H|3last = Fricke|3first = W|finallast = Richter|finalfirst = R|year = 2002|title = Anatomy of the Dog|ed =4th|city = Hannover|pub = Schlutersche GmbH & Co. KG, Verlag und Druckerei}} | {{citation|initiallast = Budras|initialfirst = K.D|2last = McCarthy|2first = P.H|3last = Fricke|3first = W|finallast = Richter|finalfirst = R|year = 2002|title = Anatomy of the Dog|ed =4th|city = Hannover|pub = Schlutersche GmbH & Co. KG, Verlag und Druckerei}} | ||
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[[Category:Respiratory System - Anatomy & Physiology]] | [[Category:Respiratory System - Anatomy & Physiology]] | ||
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Revision as of 19:12, 29 December 2010
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Introduction
Ventilation is the movement of air into and out of the lungs. Air moves from high pressure to low pressure with the rate of flow being proportional to the pressure difference. As environmental pressure is generally constant, the respiratory system must change its internal pressure to maintain air flow. The lungs are not fixed to the thoracic wall, but follow the changing volume of the thoracic cavity thanks to the pleura.
Inspiration
During Inspiration, the pressure within the pleural cavity drops to less than the pressure of the external environment. This is achieved by increasing the lung volume, brought about by the Inspiratory Muscles. The diaphragm contracts, causing the dome to flatten and move caudally. The external intercostal muscles contract, causing the ribs to be pulled outwards cranially.
Expiration
During Expiration, the pressure within the pleural cavity increases to greater than that of the external environment, in order to expel air from the lungs. This is achieved by decreasing the lung volume, and is brought about by relaxation of inspiratory muscles. The dome of the diaphragm is pushed back by the intrathoracic pressure and the ribs recoil back to their original position.
Species Differences
Avian ventilation is different to mammalian ventilation, requiring different muscles.
References
Budras, K.D., McCarthy, P.H., Fricke, W. and Richter, R. (2002) Anatomy of the Dog. 4th ed. Hannover: Schlutersche GmbH & Co. KG, Verlag und Druckerei.