During wakefulness, breathing is controlled by two interacting systems. The first is an automatic, metabolic system who control is centered in the brain stem. It subconsciously adjusts breathing rate and depth in order to regulate the levels of carbon dioxide (CO2) and oxygen (O2), and the acid-ba ratio in the blood. The cond system is the voluntary, behavioral system. Its control center is bad in the forebrain, and it regulates breathing for u in speech, singing, sighing, and so on. It is capable of ignoring or overriding the automatic, metabolic system and produces an irregular pattern of breathing.暮光之城 女主角
incinerateDuring NREM (the pha of sleep in which there is no rapid eye movement) breathing becomes deeper and more regular, but there is also a decrea in the breathing rate, resulting in less air being exchanged overall. This occurs becau during NREM sleep the automatic, metabolic system has exclusive control over breathing and the body us l
ess oxygen and produces less carbon dioxide. Also, during sleep the automatic metabolic system is less responsive to carbon dioxide levels and oxygen levels in the blood. Two things result from the changes in breathing control that occur during sleep. 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. Second, once sleep is fully obtained, there is an increa of carbon dioxide and a decrea of oxygen in the blood that persists during NREM.
暴力英语But that is not all that changes. During all phas of sleep, veral changes in the air passages have been obrved. It takes twice as much effort to breathe during sleep becau of greater resistance to airflow in the airways and changes in the efficiency of the muscles ud for breathing. Some of the muscles that help keep the upper airway open when breathing tend to become more relaxed during sleep, especially during REM (the pha of sleep in which there is rapid eye movement). Without this muscular action, inhaling is like sucking air out of a balloon—the narrow passages tend to collap. Also there is a regular cycle of change in resistance between the two sides of the no. If som
ething blocks the "good" side, such as congestion from allergies or a cold, then resistance increas dramatically. Coupled with the factors is the loss of the complex interactions among the muscles that can change the route of airflow from no to mouth.
Other respiratory regulating mechanisms apparently cea functioning during sleep. For example, during wakefulness there is an immediate, automatic, adaptive increa in breathing effort when inhaling is made more difficult (such as breathing through a restrictive face mask). This reflexive adjustment is totally abnt during NREM sleep. Only after veral inadequate breaths under such conditions, resulting in the considerable elevation of carbon dioxide and reduction of oxygen in the blood, is breathing effort adjusted. 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 vere enough, a sleeping person will arou, clear the airway, then resume breathing and likely return to sleep.
Additional breathing changes occur during REM sleep that is even more dramatic than th
e changes that occur during NREM. The amount of air exchanged is even lower in REM than NREM becau, although breathing is more rapid in REM, it is also more irregular, with brief episodes of shallow breathing or abnce of breathing. In addition, breathing during REM depends much more on the action of the diaphragm and much less on rib cage action.
Paragraphy1: 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. Movements of the rib cage for breathing are reduced during sleep, making the contractions of the diaphragm more important. Yet becau of the physics of lying down, the stomach applies weight against the diaphragm and makes it more difficult for the diaphragm to do its job. However, there are many other changes that affect respiration when asleep.
noi是什么意思xues托福TPO24阅读真题Breathing During Sleep题目
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同等学力英语1. According to paragraph 1, which of the following can be inferred about the diaphragm during sleep
