Mechanics of Breathing


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anil    on Feb 09, 2012 Says :

The breathing mechanism is nicely covered
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1 :
2 : 23/02/2012 Chest Dr. Salwa El-Sobkey 2 Chest Dr. Salwa El-Sobkey
3 : 23/02/2012 Chest Dr. Salwa El-Sobkey 3 Mechanics of Breathing The respiratory muscles are the only skeletal muscles vital to life...\Videos\3D view of diaphragm.mp4
4 : 23/02/2012 Chest Dr. Salwa El-Sobkey 4 Resting At rest the diaphragm extends upwards almost to nipple level.
5 : Mechanics of breathing ..\Videos\Breathing Movements.mp4 23/02/2012 Chest Dr. Salwa El-Sobkey 5
6 : 23/02/2012 Chest Dr. Salwa El-Sobkey 6 Inspiration Contraction of the diaphragm flatten it, displacing the abdominal viscera downwards by 5-7 cm and creating negative intra thoracic pressure, which sucks air into the lungs.
7 : 23/02/2012 Chest Dr. Salwa El-Sobkey 7 Inspiration, cont. The contracting diaphragm presses down against the fulcrum of the abdominal contents and when, the limit of abdominal wall compliance is reached, outwards against the lower rib cage, causing expansion of the lower chest.
8 : 23/02/2012 Chest Dr. Salwa El-Sobkey 8 Inspiration, cont.
9 : 23/02/2012 Chest Dr. Salwa El-Sobkey 9 Inspiration, cont. The external intercostal muscles stabilize the chest wall so that diaphragmatic contraction can create these pressure changes.
10 : 23/02/2012 Chest Dr. Salwa El-Sobkey 10 Inspiration, cont. Other necessary muscles are the scalenes, which stabilize the upper rib cage to prevent it being pulled downwards, and pharyngeal muscles, which prevent collapse of the upper airway.
11 : 23/02/2012 Chest Dr. Salwa El-Sobkey 11 Inspiration, cont. During arm activity, intercostal and accessory respiratory muscles are obliged to stabilize the torso, leaving the diaphragm to take a greater load.
12 : 23/02/2012 Chest Dr. Salwa El-Sobkey 12 Expiration Normal expiration is largely passive, by lung elastic recoil. Elastic recoil is caused by: Surface tension acting throughout the vast gas-liquid interface lining the alveoli, Elasticity of lung tissue that has been stretched during inspiration.
13 : 23/02/2012 Chest Dr. Salwa El-Sobkey 13 Expiration, cont.
14 : 23/02/2012 Chest Dr. Salwa El-Sobkey 14 Expiration, cont. The transition between inspiration and expiration is smoothed by a brake on expiratory flow caused by airway resistance, specially at the larynx, and continued low-grade inspiratory muscle activity. Airways are narrower during expiration than inspiration so that it is more difficult to empty the lungs than to fill them.
15 : 23/02/2012 Chest Dr. Salwa El-Sobkey 15 Expiration, cont. Active expiration occurs with exercise, speeds, coughing and sneezing.
16 : Power of breathing Please note that the power or engine of breathing is the pressure gradient. ..\Videos\Mechanics of Breathing - 12.mp4 23/02/2012 Chest Dr. Salwa El-Sobkey 16
17 : Thoracic movement ..\Videos\rib cage breathing.mp4 23/02/2012 Chest Dr. Salwa El-Sobkey 17
18 : 23/02/2012 Chest Dr. Salwa El-Sobkey 18 Thoracic movement Two types of movements have been described : The pump-handle movement: The upper ribs are limited in their ability to move. Each pair swings like pump handle, with elevation thrusting the sternum forward. This forward movement increases the anteroposterior diameter and the depth of the thorax and is called the pump- handle movement.
19 : 23/02/2012 Chest Dr. Salwa El-Sobkey 19 Thoracic movement, cont. The bucket-handle movement: In the lower ribs, there is little anteroposterior movement. During inspiration, the ribs swing outward and upward, each pushing against the rib above during elevation. This bucket-handle movement increases the transverse diameter of the thoracic cage.
20 : 23/02/2012 Chest Dr. Salwa El-Sobkey 20 Thoracic movement, cont. Thus during inspiration, the thorax increases its volume by increasing its anteroposterior and transverse diameters.
21 : 23/02/2012 Chest Dr. Salwa El-Sobkey 21 Thoracic movement, cont.
22 : 23/02/2012 Chest Dr. Salwa El-Sobkey 22 Pressure Alveolar pressure: Pressure inside the lung Pleural (intra pleural/ intra thoracic) pressure: Pressure in the pleural sac Transpulmonary (transmural) pressure: Pressure difference inside and outside lung, i.e. the difference between the above two pressures, representing the driving pressure responsible for inflating the lungs
23 : 23/02/2012 Chest Dr. Salwa El-Sobkey 23 Pressure, cont. Alveolar pressure is negative on inspiration and slightly positive on expiration. Pleural pressure is normally negative because of inward pull from lung recoil and outward pull from chest wall recoil. This creates an average negative pleural pressure of -2cmH2O at end-expiration and -6cmH2O at end-inspiration.
24 : 23/02/2012 Chest Dr. Salwa El-Sobkey 24 Resistance Resistance is present whenever there is airflow through a tube because gas slides against the walls and over itself. Peripheral resistance is low because the large number of small airways create a wide total cross-sectional area. The upper respiratory tract, whose total cross-section is narrow and airflow turbulent, causes higher resistance.
25 : 23/02/2012 Chest Dr. Salwa El-Sobkey 25 Resistance, cont. The nasal route resists airflow more than the oral route, that is why we breath through the mouth when breathless or exercising. Airflow resistance is responsible for about 80% of the work of breathing. Lung parenchyma contributes the remaining 20%.
26 : 23/02/2012 Chest Dr. Salwa El-Sobkey 26 Compliance Compliance= change in volume/ change in pressure Compliance is the ease with which the lungs inflate. It reflects their ability to extend and recoil.
27 : 23/02/2012 Chest Dr. Salwa El-Sobkey 27 Compliance, cont. The lung is least compliant, i.e. stiffest, at either extreme of lung volume, so that it is difficult to inflate alveoli that are closed or hyper inflate those that are fully inflated, in the same way that blowing up a balloon is most difficult at either extreme.
28 : 23/02/2012 Chest Dr. Salwa El-Sobkey 28 Compliance, cont. The contribution of lung parenchyma to compliance is related partly to tissue elasticity but mostly to surfactant in alveolar fluid. This acts like detergent to decrease surface tension and prevent the wet alveolar walls sticking together, a force that can be likened to trying to peel open a plastic bag that is wet inside.
29 : 23/02/2012 Chest Dr. Salwa El-Sobkey 29 Work of breathing Work of breathing (WOB) can be defined in two ways: The pressure required to move a volume of gas, i.e. trans pulmonary pressure X tidal volume. Oxygen consumed by the respiratory muscles, i.e. the oxygen cost of breathing.
30 : 23/02/2012 Chest Dr. Salwa El-Sobkey 30 Reference Alexandra Hough: Physiotherapy in respiratory care, nelson thornes, 2001
31 : 23/02/2012 Chest Dr. Salwa El-Sobkey 31 Thank you
32 : 23/02/2012 Chest Dr. Salwa El-Sobkey 32 ????? ?????? ????? ???? ?????? ???????? ? ??? ??????? ???????? ? ??? ?? ?????? ? ??? ?? ?????? ? ???? ?? ??????? ? ??? ?????? ? ?? ??????. ?? ???? ????? ??? ???? ? ?? ???? ??? ??? ????.

 

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Description of how the diaphragm contract and the thoracic cage move to produce change in the size    more
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