For example, a certain number of gas molecules in a two-liter container has more room than the same number of gas molecules in a one-liter container. In a gas, pressure is a force created by the movement of gas molecules that are confined. Inspiration (or inhalation) and expiration (or exhalation) are dependent on the differences in pressure between the atmosphere and the lungs. However, the ability to breathe-to have air enter the lungs during inspiration and air leave the lungs during expiration-is dependent on the air pressure of the atmosphere and the air pressure within the lungs. The alveolar and intrapleural pressures are dependent on certain physical features of the lung. The major mechanisms that drive pulmonary ventilation are atmospheric pressure ( P atm) the air pressure within the alveoli, called alveolar pressure ( P alv) and the pressure within the pleural cavity, called intrapleural pressure ( P ip). Pulmonary ventilation is the act of breathing, which can be described as the movement of air into and out of the lungs.
![muscles of inspiration muscles of inspiration](https://image.slidesharecdn.com/respirationnew2-140104152715-phpapp01/95/pua-respiration-10-638.jpg)
List the steps involved in pulmonary ventilation.Discuss how pressure, volume, and resistance are related.Describe the mechanisms that drive breathing.Philadelphia: Lea and Febiger.By the end of this section, you will be able to: Kinesiology and applied anatomy (6th ed.). (full text version is available on Medline Unique Identifier: 97362737). Medicine and Science in Sports and Exercise, 29, 738-54. Diaphragm structure and function in health and disease. Poole, D.C., Sexton, W.L., Farkas, G.A., Powers, S.K., Reid, M.B. Kapandji, The physiology of the joints: Vol. Functional components of the vertebral column. Retrieved from Octofrom Florida State University, General Chemistry 1, A Virtual Textbook Web site: Ĭlemente, C.D. Because of the orientation of the lower ribs' attachments to the vertebrae, rib elevation expands the thorax' lateral dimensions.īlaber, M. Therefore, the diaphragm's muscular lines of application elevate the lower ribs. When the central tendon becomes stable, it is still superior to the diaphragm's mobile attachments on the lower ribs. compressed abdominal contents, which push upward on the descending diaphragm.elongated mediastinal structures, which pull upward on the diaphragm."Top down" view of diaphragm (Clemente, 1981, Fig.193) showing location of central tendon.ĭuring inspiration, the diaphragm's central tendon descends until it is fixed or stabilized by forces that develop in: Some authors classify the quadratus lumborum and latissimus dorsi as secondary muscles of expiration, but the reasoning is not as clear as with the muscles listed in the table.ĭiagrams of secondary (accessory) muscles of respirationĪnterior view of diaphragm (Rasch & Burke, 1974, Fig.14-3) showing its lines of application where it attaches to the ribs and to the central tendon. 'HIGH PRESSURE' AIR IN LUNG FLOWS OUT TOWARD 'LOW PRESSURE' EXTERIOR. 'HIGH PRESSURE' EXTERIOR AIR FLOWS INTO 'LOW PRESSURE' LUNG. Thoracic movement during inspiration and expiration
![muscles of inspiration muscles of inspiration](https://i.pinimg.com/originals/7a/2a/a3/7a2aa32af69c4b172ae033e37cca8bcf.jpg)
The xiphoid process is an anterior surface landmark for the inferior boundary of lung substance (Clemente, 1981, Fig.128).Ĥ. The T10 spinous process is a posterior surface landmark for the inferior boundary of lung substance (Clemente, 1981, Fig.129). At a given temperature, is a constant quantity.When the intrathoracic pressure is high,Īir (at atmospheric pressure) flows out of the lung.When the intrathoracic pressure is low,Īir (at atmospheric pressure) flows into the lung.
![muscles of inspiration muscles of inspiration](https://i.ytimg.com/vi/YpllpAAeir4/maxresdefault.jpg)
Thoracic movement during inspiration and expiration.BIOMECHANICS OF RESPIRATION Biomechanics of respiration