What is the purpose of surfactant in the lungs?

Purpose. Surfactant reduces the surface tension of fluid in the lungs and helps make the small air sacs in the lungs (alveoli) more stable. This keeps them from collapsing when an individual exhales. In preparation for breathing air, fetuses begin making surfactant while still in the womb.
A.

How does surfactant increases lung compliance?

Compliance is the ability of lungs and thorax to expand. Pulmonary surfactant thus greatly reduces surface tension, increasing compliance allowing the lung to inflate much more easily, thereby reducing the work of breathing. It reduces the pressure difference needed to allow the lung to inflate.
  • What are the factors that affect lung compliance?

    It is affected by the elastic properties of the lung, which are reduced in emphysema, where lung compliance is high. Lung compliance can be reduced in diseases such as idiopathic pulmonary fibrosis, where the elastic fibres of the lung (elastin) are replaced by stiffer collagen.
  • What happens to the lungs of Intrapleural pressure equals or increases above atmospheric pressure?

    If intrapleural pressure becomes equal to atmospheric pressure, lung collapse will occur. Explain exactly what happens, in terms of volume and pressure changes in the lungs, when these muscles contract. The contraction of the diaphragm causes an increase in the height of the thoracic cavity.
  • What is the purpose of surfactant in the lungs?

    Purpose. Surfactant reduces the surface tension of fluid in the lungs and helps make the small air sacs in the lungs (alveoli) more stable. This keeps them from collapsing when an individual exhales. In preparation for breathing air, fetuses begin making surfactant while still in the womb.
B.

How does surfactant keep the lungs dry?

3) Surfactant helps keep the alveoli relatively "dry" - a high surface tension would suck fluid away from the alveolar walls into the alveolar space but with the decreased surface tension provided by surfactant, the alveolar space is maintained in a "relatively dry state" (ie.
  • What keeps the alveoli dry?

    3) Surfactant helps keep the alveoli relatively "dry" - a high surface tension would suck fluid away from the alveolar walls into the alveolar space but with the decreased surface tension provided by surfactant, the alveolar space is maintained in a "relatively dry state" (ie.
  • How is the concentration gradient maintained in the lungs?

    Adaptations of the alveoli. Each alveolus is surrounded by blood capillaries which ensure a good blood supply. This is important as the blood is constantly taking oxygen away and bringing in more carbon dioxide - which helps to maintain the maximum concentration gradient between the blood and the air in the alveoli.
  • Why do alveoli appear to be different sizes?

    Small areas have the surface tension reduced much more than large areas. Thus, if alveoli did not have surfactant, and the surface tension therefore was the same in alveoli of all sizes, you would expect air to flow from smaller alveoli into larger alveoli. In other words, the smaller alveoli would tend to collapse.

Updated: 16th October 2019

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