Difference between revisions of "Ventilation - Anatomy & Physiology"
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*During Inspiration, the pressure within the [[Pleural cavity and membranes - Anatomy & Physiology|Pleural Cavity]] drops to less that the pressure of the external environment. | *During Inspiration, the pressure within the [[Pleural cavity and membranes - Anatomy & Physiology|Pleural Cavity]] drops to less that the pressure of the external environment. | ||
*This is achieved by increasing the lung volume, brought about by the Inspiratory Muscles: | *This is achieved by increasing the lung volume, brought about by the Inspiratory Muscles: | ||
| − | **[[Diaphragm - Anatomy & Physiology|Diaphragm]] - | + | **[[Diaphragm - Anatomy & Physiology|Diaphragm]] - contracts - causing the dome to flatten and moe caudally. |
| − | **[[Intercostal Muscles - Anatomy & Physiology|Intercostal muscles]] | + | **[[Intercostal Muscles - Anatomy & Physiology|Intercostal muscles]] - External Intercostal Muscles contract - causing the ribs to be pulled outwards cranially. |
| − | == | + | ==Expiration== |
| − | + | During Expiration, the pressure within the [[Pleural cavity and membranes - Anatomy & Physiology|Pleural Cavity]] increases to greater than that of the external environment, in orfer to expel air from the lungs. This is achieved by decreasing the lung volume, caused by relaxation of Inspiratory Muscles: | |
| + | **Dome of the Diaphragm is pushed back by the intrathoracic pressure. | ||
| + | **Ribs recoil to origin position. | ||
* | * | ||
Revision as of 12:38, 13 August 2008
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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 it's internal pressure to maintain air flow.
Inspiration
- During Inspiration, the pressure within the Pleural Cavity drops to less that the pressure of the external environment.
- This is achieved by increasing the lung volume, brought about by the Inspiratory Muscles:
- Diaphragm - contracts - causing the dome to flatten and moe caudally.
- Intercostal muscles - 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 orfer to expel air from the lungs. This is achieved by decreasing the lung volume, caused by relaxation of Inspiratory Muscles:
- Dome of the Diaphragm is pushed back by the intrathoracic pressure.
- Ribs recoil to origin position.