jawaban blood pressure passage one toefl

(15) of the vital ecological role alders play.Īmong the alder's valuable ecological contributions is its capacity to fix nitrogen in nitrogen-deficient soils. But times are changing a new generation of foresters seems better prepared to include in their management plans consideration it appears that both kind of sleep are necessary, and the recuperation of sleep of one kind will not compensate for a lack of the other kind of sleep.Companies engaged in intensive timber cropping naturally take a dim view of alders suppressing more valuable evergreen trees.

Studies suggest that non-REM sleep may be especially helpful in restoring muscle control, whereas REM sleep may be more important in revitalizing mental activity. NREM sleep increases after physical exertion, whereas REM sleep tends to increase after a stressful day. Since people who suffer sleep deprivation experience fatigue, irritably, and loss concentration, we must conclude that sleep is essential because in some way it regenerates the brain and the nervous system. Later instance of REM sleep are usually of longer duration than are instances earlier in the eight-hour period. Each instance lasts from five to thirty minutes with an interval of at least ninety minutes between each one. In a period of eight hours, most sleepers experience from three to five instances of REM sleep. In contrast, the body is so still that the dreamer may appear to be paralyzed. The heart beats irregularly, and blood pressure may be elevated.

Sleep of this kind is called dreaming sleep or rapid- eye-movement sleep, also known REM sleep. Sleepers who are awakened during this rapid- eye movement sleep will often recall the details of dreams they have been having. The eyes move rapidly, and it appears to the observer that the sleeper is watching some event.

Referred to as NREM or non-REM sleep, it is characterized by large, slow waves.ĭuring sleep, intervals of small, fast waves also occur in patterns similar to those experienced while awake. In fact, if awakened from slow-waved sleep, a person can often remember vague thoughts that occurred during that period of sleep, but the sleeper does not generally dream. The largest, slowest waves occur during the first three hours of sleep when mental activity slows down but does not stop. During wakefullness, the waves are recorded at about ten small waves per second., but with the onset of sleep, the waves become larger and slower. These waves occur in predictable sleep cycles that can be measured with an electroencephalograph, known more commonly as an EEG. Whether one is awake or asleep, the brain emits electrical waves.

Jawaban blood pressure passage one toefl