There’s more going on under your skin than you possibly realize.

Lung brush:  Working 24×7, microscopic cilia lining your bronchial passages sweep your lungs clean, allowing you to survive in an atmosphere filled with pollutants.  Science Daily summarized a paper in Science that described “A Periciliary Brush Promotes the Lung Health by Separating the Mucus Layer from Airway Epithelia” (Button et al., Science, 24 August 2012: Vol. 337 no. 6097 pp. 937–941, DOI: 10.1126/science.1223012).  Science Daily said,

“The cilia are constantly beating, even while we sleep,” he says. “In a coordinated fashion, they push mucus containing foreign objects out of the lungs, and we either swallow it or spit it out. These cilia even beat for a few hours after we die. If they stopped, we’d be flooded with mucus that provides a fertile breeding ground for bacteria.”.…

The researchers used a combination of imaging techniques to observe a dense meshwork in the periciliary layer of human bronchial epithelial cell cultures. The brush-like layer consists of protective molecules that keep sticky mucus from reaching the cilia and epithelial cells, thus ensuring the normal flow of mucus.…

“This layer — this brush — seems to be very important for the healthy functioning of human airways,” according to Rubinstein. “It protects cells from sticky mucus, and it creates a second barrier of defense in case viruses or bacteria penetrate through the mucus. They would not penetrate through the brush layer because the brush is denser.”

Respiratory diseases such as COPD are apparently caused by the collapse of this brush layer.  The new findings, which replace old notions that the mucus rested on a liquid layer, may help people suffering from a variety of lung problems.  The BBC News write-up added this comment:

Prof Stephen Spiro, vice-chairman of the British Lung Foundation, said: “Mucus has a complex biological make-up and forms a vital part of the lungs’ defence mechanism against potentially harmful or irritating substances, which are inhaled as small particles….

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