TPO24-2 BreathingDuring Sleep睡眠中的呼吸
本篇文章长难句并不多，但大部分学生都觉得难，其中一个重要原因是信息点多且碎，不易定位。今天我们就通过分析这篇文章中的一些句子，寻找其“变身”了的定位词。
1. Of all the physiological differences in human sleep compared with wakefulness that have been discovered in the last decade, changes in respiratory control are most dramatic. Not only are there differences in the level of the functioning of respiratory systems, there are even changes in how they function. (篇章开头主旨句。)
2. During NREM (the phase of sleep in which there is no rapid eye movement) breathing becomes deeper and more regular, but there is also a decrease in the breathing rate, resulting in less air being exchanged overall.
3. First, there may be a brief cessation or reduction of breathing when falling asleep as the sleeper waxes and wanes between sleep and wakefulness and their differing control mechanisms . (找到 “just before NREM sleepbegins” 了吗?)
4. It takes twice as much effort to breathe during sleep because of greater resistance to air flow in the airways and changes in the efficiency of the muscles used for breathing.(明白为什么“inhalingis like sucking air out of a balloon”了吗?)
5. This reflexive adjustment is totally absent during NREM sleep. Only after several inadequate breaths under such conditions, resulting in the considerable elevation of carbon dioxide and reduction of oxygen in the blood, is breathing effort adjusted.
6. Finally, the coughing reflex in reaction to irritants in the airway produces not a cough during sleep but a cessation of breathing. If the irritation is severe enough,a sleeping person will arouse, clear the airway, then resume breathing and likely return to sleep. (到哪里去找 “a very mildirritation”呢?)
7. The amount of air exchanged is even lower in REM than NREM because, although breathing is more rapid in REM, it is also more irregular, with brief episodes of shallow breathing or absence of breathing.
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