View Full Version : decreased alveolar surfactant

10-30-2008, 06:56 AM
Hi, just wondering if someone could help me answer this question...
what happens to the pressure and volume of the lung and pleural cavity if the amount of surfactant were decreased?

10-30-2008, 02:47 PM
hi there
i'l let in to what ever litle I know...
surfactant reduces surface tention of alveoli..
ST= pressure times radius
eg. greater the r greater the ST.Both P and ST are directed inside towards the radius.they try to collapse the alveoli.
our friend surfactant ...the gentleman also called phosphatidyl choline , formed in utero starting at 24 wks roughlyby type 2 pneumocytes can be measured in amniotic fluid by lecithin \ spingo myelin ratio which if > 2 implies its presence.
cortisol, thyroxine and prolactin want it to form and its inhibited by insulin.

now ..if surfactant were to decrease ..the interstitial lung pressure also decreases i.e bcomes more negative inviting the capillary hydrostatic pressue to overpower and leading to lung edema.

less of surfactant implies collapsing alveoli eg. RDS in primies...atelectasis...decreased lung volume, raised collapsing pressure of lung.
the [negative] intrapleural pressure increases as the lung compliance decreases.

i hope i was of sum help. tc.

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