IELTS® Academic Reading Practice 18

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Breathing During Sleep

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 because 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.

During wakefulness, breathing is controlled by two interacting systems. The first is an automatic, metabolic system whose 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-base ratio in the blood. The second system is the voluntary, behavioral system. Its control center is based in the forebrain, and it regulates breathing for use 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.

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. This occurs because during NREM sleep the automatic, metabolic system has exclusive control over breathing and the body uses less 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 these 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 increase of carbon dioxide and a decrease of oxygen in the blood that persists during NREM.

But that is not all that changes. During all phases of sleep, several changes in the air passages have been observed. It takes twice as much effort to breathe during sleep because of greater resistance to airflow in the airways and changes in the efficiency of the muscles used 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 phase 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 collapse. Also there is a regular cycle of change in resistance between the two sides of the nose. If something blocks the "good" side, such as congestion from allergies or a cold, then resistance increases dramatically. Coupled with these factors is the loss of the complex interactions among the muscles that can change the route of airflow from nose to mouth.

Other respiratory regulating mechanisms apparently cease functioning during sleep. For example, during wakefulness there is an immediate, automatic, adaptive increase in breathing effort when inhaling is made more difficult (such as breathing through a restrictive face mask). 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. 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.

Additional breathing changes occur during REM sleep that are even more dramatic than the changes that occur during NREM. 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. In addition, breathing during REM depends much more on the action of the diaphragm and much less on rib cage action.




This reading practice simulates one part of the IELTS Academic Reading test. You should spend about twenty minutes on it. Read the passage and answer questions 27-40.
Questions 27-34
Do the following statements agree with the information given in the reading passage? In boxes 27-34 on your answer sheet, write

YES   if the statement reflects the claims of the writer
NO   if the statement contradicts the claims of the writer
NOT GIVEN   if it is impossible to say what the writer thinks about this

27. The diaphragm helps with breathing as movements of the rib cage increases during sleep.

28. During NREM sleep breathing rate decreases.

29. An increase in the oxygen level in the blood can occur as sleep becomes fully obtained.

30. The automatic, metabolic system increases its dependence on air exchanges during NREM sleep.

31. The heart rate slows down during NREM sleep.

32. Because breathing is more shallow and irregular in REM than in NREM, less air is exchanged in REM

33. Breathing is faster in NREM sleep than in REM sleep

34. The role of the rib cage increases during REM.

Questions 35-37
Choose three letters A-F.

Write your answers in boxes 35-37 on your answer sheet.

Which THREE of the following are stated about the two breathing systems?
  1. The concentration of carbon dioxide is regulated by the voluntary breathing system.
  2. The voluntary breathing system has its control center in the brain stem.
  3. Voluntary control of breathing is located in the forebrain.
  4. The voluntary breathing system is able to bypass the automatic system.
  5. The voluntary breathing system produces a regular breathing pattern.
  6. The automatic generation of respiratory patterns resides in the brain stem.

35

36

37

Questions 38-40
Choose the correct letter, A, B, C or D.

Write your answers in boxes 38-40 on your answer sheet.

38. All of the following are mentioned as being characteristic of breathing during sleep EXCEPT?

39. What happens during NREM sleep when inhaling is difficult?

40. A very mild irritation during sleep will likely cause the sleeping person to …




Answer Sheet
1
N/A
2
N/A
3
N/A
4
N/A
5
N/A
6
N/A
7
N/A
8
N/A
9
N/A
10
N/A
11
N/A
12
N/A
13
N/A
14
N/A
15
N/A
16
N/A
17
N/A
18
N/A
19
N/A
20
N/A
21
N/A
22
N/A
23
N/A
24
N/A
25
N/A
26
N/A
27
28
29
30
31
32
33
34
35
36
37
38
39
40


Reading Passage Vocabulary
Breathing During Sleep


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 because 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.

During wakefulness, breathing is controlled by two interacting systems. The first is an automatic, metabolic system whose 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-base ratio in the blood. The second system is the voluntary, behavioral system. Its control center is based in the forebrain, and it regulates breathing for use 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.

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. This occurs because during NREM sleep the automatic, metabolic system has exclusive control over breathing and the body uses less 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 these 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 increase of carbon dioxide and a decrease of oxygen in the blood that persists during NREM.

But that is not all that changes. During all phases of sleep, several changes in the air passages have been observed. It takes twice as much effort to breathe during sleep because of greater resistance to airflow in the airways and changes in the efficiency of the muscles used 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 phase 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 collapse. Also there is a regular cycle of change in resistance between the two sides of the nose. If something blocks the "good" side, such as congestion from allergies or a cold, then resistance increases dramatically. Coupled with these factors is the loss of the complex interactions among the muscles that can change the route of airflow from nose to mouth.

Other respiratory regulating mechanisms apparently cease functioning during sleep. For example, during wakefulness there is an immediate, automatic, adaptive increase in breathing effort when inhaling is made more difficult (such as breathing through a restrictive face mask). 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. 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.

Additional breathing changes occur during REM sleep that are even more dramatic than the changes that occur during NREM. 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. In addition, breathing during REM depends much more on the action of the diaphragm and much less on rib cage action.

 
IELTS Academic Reading Tips for Success
These are general tips that will appear on all reading questions.

Tips to improve your reading speed
To get a high score on the IELTS reading section, you need to have a fast reading speed. To have a fast reading speed, you need to improve your vocabulary and practice dissecting sentences. One strategy to dissect a sentence is to look for the subject and verb of the sentence. Finding the subject and verb will help you better understand the main idea of said sentence. Keep in mind, a common feature of a IELTS reading passage is to join strings of ideas to form long compound sentences. This produces large chunks that students have a hard time absorbing. Do not get overwhelmed by its length, just look for the subject and verb, the rest of the ideas will flow.


Keep in mind, having a slow reading speed makes skimming or scanning a reading passage more difficult. The process of quickly skimming through a reading passage for specific keywords or main ideas is a requirement for you to employ successful reading strategies to improve your IELTS reading score. In other words, skimming and scanning are critical skills to ensure you complete all questions in the allotted time frame.
IELTS Reading Strategies
Once you can read and comprehend a passage with a rate of, at least, 220 words per minute, you'll be ready to start implementing our strategies. All too often, students spend too much time reading the passages and not enough time answering the questions. Here is a step by step guide for tackling the reading section.

  1. Step 1: Read questions first

    One of the most common mistakes that candidates make when approaching the reading exam is reading every single word of the passages. Although you can practice for the exam by reading for pleasure, "reading blindly" (reading without any sense of what the questions will ask) will not do you any favors in the exam. Instead, it will hurt your chances for effectively managing your time and getting the best score.

    The main reason to read the questions first is because the type of question may determine what you read in the passage or how you read it. For example, some question types will call for the "skimming" technique, while others may call for the "scanning" technique.

    It is important to answer a set of questions that are of the same question type. You'll need to determine which question type you want to tackle first. A good strategy would be to start with the easier question type and move on to more difficult question types later. The Easiest question types are the ones where you spend less time reading. For example, the Matching Heading question type is an easier one because you only need to find the heading that best describes the main idea of a paragraph. An example of a difficult question type would be Identifying Information. For this question type, you'll need to read each paragraph to find out if each statement is TRUE, FALSE, or NOT GIVEN according to the passage.

    Here is a table that lists the difficulty levels for each question type. Use this table as a reference when choosing which question type you want to tackle first.


    Difficulty level Question Type
    Easy Sentence Completion
    Short answer
    Medium Matching Features
    Multiple choice
    Matching Headings
    Summary, Table, Flow-Chart Completion
    Difficult Matching Sentence Endings
    Matching Information
    Identifying Information (TRUE/FALSE/NOT GIVEN)
    Identifying Viewer's claims (YES/NO/NOT GIVEN)

  2. Step 2: Read for an objective

    After you've read the questions for the passage, you will be able to read for an objective. What does this mean? For example, if you come across a question that includes the year "1896", you can make a note of when this year comes up in the text, using it to answer the question later on. There are two reading techniques that will help you stay on track with reading for an objective. The first one, skimming, is best defined as reading fast in order to get the "gist", or general idea, or a passage. With this technique, you are not stopping for any unfamiliar words or looking for specific details. The second technique, scanning, is best defined as reading for specific information. With this technique, you are not reading for the overall gist, but rather, specific information. Notice how each of these techniques has a specific objective in mind. This will help you find information more quickly.

  3. Step 3: Take notes

    As you're reading for an objective, you should also be making notes on the margins of the passage, placing stars next to key information, or underlining things that you believe will help you answer the various questions. This will make it easier for you to check back when you are asked certain things in the questions. Choose whichever note-taking system is right for you - just make sure you do it!

  4. Step 4: Answer wisely

    After you've read the questions, read the passage, and have taken any appropriate notes, you you should have located the part of the text where you where you need to read carefully. Then just read carefully and think critically to determine the correct answer.

IELTS Reading Question Types
 
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