5. What muscles are more important for deep inhalations?

6. What muscles are not active during quiet breathing?

7. Is expiration normally a passive process?

8. Are the lung and chest wall elastic?

9. Where are expiratory muscles used in?

10. Where do the internal intercostal muscles pull the ribs?

Make the sentences of your own using the new words (10 sentences).

Make your own sentences using SOME, ANY, NO, EVERY (10 sentences).

Find one word, which is a little bit different in meaning from others (найдите одно слово, которое немного отличается от других по смыслу):

1) a) air; b) muscles; c) organs;

2) a) eyes; b) brows; c) arms;

3) a) teeth; b) tongue; c) ligament;

4) a) coccyx; b) pelvis; c) shoulder;

5) a) elbow; b) arm; c) ear.

In a liquid, the proximity of adjacent molecules results large, inter-molecular, attractive (Van der Waals) forces that serve to stabilize the liquid. The liquid-air surface produces inequality of forces that are strong on the liquid side and weak on the gas side because of the greater distance between molecules in the gas phase. Surface tension causes the surface to maintain as small an area as possible. In alveoli, the result a spherically-curved, liquid lining layer that tends to be pulled inward toward the center of curvature of the alveolus. The spherical surface of the alveolar liquid lining behaves in manner similar to a soap bubble. The inner and outer surface of a bubble exert an inward force that creates a greater pressure inside than outside the bubble. Interconnected alveoli of different sizes could lead to collapse of smaller alveoli (atelectasis) into larger alveoli, because of surface tension, the pressure inside the small alveolus (smaller radius of curvature) is greater than that of the larger alveolus. Without surfactant, gas would therefore move from smaller to larger alveoli, eventually producing or giant alveolus.

Pulmonary surfactant: Pulmonary surfactant is a phospholipid (comprised primari ly of dipalmitoyl phosphatidylcholine) synthesized by type II alveolar epithelial cells. Surfactant reduces surface tension, thereby preventing the collapse of small alveoli. Surfactant increases the compliance of the lung and reduces the work of breathing.

Surfactant keeps the alveoli dry because alveolar collapse tends to draw fluid into the alveolar space. Surfactant can be produced in the fetus as early as gestational week 24, but is synthesized most abundantly by the 35 th week of gestation. Neonatal respiratory distress syn drome can occur with premature infants, and results in areas of atelec-tasis, filling of alveoli with transudate, reduced lung compliance, and V/Q mismatch leading to hypoxia and CO_>2 retention.

New words

surface tension forces – поверхностные силы напряжения

liquid – жидкость

proximity – близость

adjacent – смежный

large – большой

intermolecular – межмолекулярный

to stabilize – стабилизироваться

surface – поверхность

to produce – производить

side – сторона

weak – слабый

greater – больше