CONVERT THE FOLLOWING PARAGRAPH INTO PASSIVE VOICE. PARAGRAPH: E .dl 95% 1 1 :01

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CONVERT THE FOLLOWING PARAGRAPH INTO PASSIVE VOICE.

PARAGRAPH:

E .dl 95% 1 1 :01 Sign in to edit and save changes to this At the anterior ends of the nasal septum and turbinates, the squamous epithelium is replaced by areas of ciliated epithelium. There are approximately five ciliated to every non-ciliated cell, each ciliated cell having about 200 cilia extending from the anterior surface. Under normal conditions, these cells have a life of four to eight weeks2. Ciliary action clears surface fluid into the nasopharynx, where there is a transition to squamous epithelium. From here the mucus can be wiped off by the action of the soft palate and swallowed. There is also a small area in the anterior nose where ciliary action moves particles forward, from where they can then be removed by sneezing, wiping or blowing the nose. The sneeze reflex is similar to the cough reflex except that it applies to the nasal passages rather than the lower respiratory airways. During a sneeze, the uvula is depressed to channel the air through the nose and mouth to help clear the nasal passages of the irritation. Efficient mucociliary clearance is a function of the physical properties of the mucus coupled to appropriately functioning cilia. Nasal mucus is secreted into the airway from goblet cells and mucus glands as a homogeneous gel. This floats on a 'sol or periciliary layer that bathes the cilia, in a similar manner to the mucus lining the upper respiratory tract (Chapter 10). The mucus or gel layer acts like a conveyor belt over the 'sol layer which is produced from serous glands and by transudation. The cilia are approximately 6 um long and the tip of each protrudes through the 'sol' layer into the mucus layer to propel it in an antrograde direction. The coordinated beating of the cilia moves the mucus layer along towards the pharynx. The ciliary beat frequency is estimated to be between 12-20Hz3. Intersubject variations of ciliary beat frequency are small but there is a highly significant correlation between the beat frequency and log of mucus transport time in vivo, indicating that this plays an important role in controlling nasal mucociliary clearance4 5. The filtering and deposition of airborne particles occurs predominantly by inertial impaction. The regions of highest deposition are those where the airstream bends sharply allowing the momentum of the particles to deviate from the air path6. Hence, impaction Downloaded by [Saudi Digital Library] at 09:33 30 January 2014 204 Physiological Pharmaceutics

Explanation / Answer

The squamous epithelium is replaced by areas of ciliated epithelium at the anterior ends of the nasal septum and turbinates. There are approximately five ciliated to every non-ciliated cell, extending from the anterior surface, each ciliated cell have about 200 cilia, these cells have a life of 4 to 8 weeks. Surface fluid is cleared into the nasopharynx by ciliary action, where there is transition to squamous epithelium.

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