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Biomechanics of breathing. Lungs ventilation

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1 Biomechanics of breathing. Lungs ventilation




5 Respiration External respiration (Ventilation and the exchange of gases (oxygen and carbon dioxide) between the air and blood ) Internal respiration (oxygen utilization by the tissues)

6 Airway zones Conductive (Leading ) zone Transient (transit ) zone
Respiratory zone Of the total volume of the lungs conductive zone is about 150 ml, transient - about 1500 ml.

7 Functions of the respiratory pathways
1. Warming. 2. Moisturizing. 3. Clearing the air Inhaled air: t C, 45-55% BB In the bronchi: t 37 ° C, 100% BB

8 Respiratory muscles Main muscles for inspiration: diaphragm and external intercostal, intercartilaginous muscles Muscles for expiration: internal intercostal, pectoral, abdominal muscles

9 Calm inspiration is an active process
Calm inspiration is an active process. The contraction of the inspiratory muscles and diaphragm increases intrathoracic volume. It stretches the thorax and lungs. Calm expiration is a passive process. The thorax and lungs recoil when the respiratory muscles relax.

10 Inspiration the dome of the diaphragm flattens, ribs elevate
In the rest, 4/5 of inhalational work is done by diaphragm. Pressure in the alveoli reduces below atmospheric, the air moves under pressure gradient into the lungs



13 Exhalation Normally is a passive process. After relaxation of muscles, due to the elastic tension of thorasic tissues air is removed (Becoming active during bronchial obstruction)



16 Inspiration Exspiration

17 Effect of Rib and Sternum Movement on Thoracic Volume


19 Pressure in the lungs and intrapleural pressure
Intrapleural pressure is always lower than the alveolar one: First: chest is a sealed container. Second, the lungs are characterized by elastic tension, which is due to these factors: 1. presence of ellastic fibers, which make 1 / 3 of elastic tention; 2. surface tension of the liquid layer on the inner surface of alveoli, which makes 2 / 3 of the elastic tension of the lungs. Thirdly, “negative” pressure in the pleural cavity is maintained by the large absorbtion capacity of pleural leaves.



22 Physiological dead space

23 Breathing act (respiratory movements):
inspiration expiration, their value on average equals to 1:1,2 in adults.   The frequency of respiratory movements in an adult respiratory movements for 1 minute.

24 Evaluation of functional state of the respiratory system
1. Tidal volume (breathing air) - a volume of air that is inhaled or exhaled at rest. Normally it is - 0,3-0,8 l (mean 0.5 ml). 2. Inspiratory reserve volume (additional air) - is the maximum volume of air you can inhale above after the calm inspiration. Normally it is l. 3. Expiratory reserve volume (air backing) - is the maximum volume of air you can exhale above after the calm expiration. Normally it is 1,0-1,5 liters. 4. Residual volume (residual air) - the amount of air that remains in the lungs after maximum exhalation. Normally it is 1,0-1,5 liters.



27 Spirometer, Lung Volumes, and Lung Capacities


29 Lung capacity 1. The total maximum lung capacity - the maximum volume of air that fits in the lungs or the sum of all lung volumes. Normally is 4,5-6,5 liters. 2.Vital lung capacity - the largest amount of air you can exhale after maximum inhalation or the amount of the first three volumes. Normally it is: women - 3,0-3,5 l; in men - 3,5-5,0 liters. 3. Inspiratory capacity - the maximum amount of air you can breathe after calm exhalation, or the amount of the first two volumes. Normally it - 1,8-2,8 liters. 4. Functional residual capacity - the amount of air contained in the lungs after calm exhalation or the amount of the last two volumes. Normally liters.

30 Appropriate Vital Capacity value
Men [ (0.112 x · age in years)] · height in cm for women [ (0.101 · age in years)] · height in cm Normally the actual VC can deviate up to 15%

31 Alveolar ventilation Alveolar ventilation is a volume of air that enters the alveoli of the lungs per unit of time. Alveolar ventilation = (TV - Dead Space) · BR



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