每日一练：职称英语考试卫生类每日一练(2019/2/22)
【单选题】
High Stress May Damage Memory
According to a report issued in May 1998,elderly people who consistently high blood levels of the stress hormone. What'smore ,high levels of cortisol are also associated with shrinking of thehippocampus（海马区）, a region of the brain that plays akey role in learning and memory.
The findings suggest that even cortisol levelsin the normal, "healthy" range can actually accelerate brain aging.
The study results "now provide substantialevidence that long-term exposure to adrenal（肾上腺） stresshormones may promote hippocampal aging in normal elderly humans, "writeNada porter and Phillip Landfield. Cortisol is a hormone releases in responseto stress by the adrenal glands（腺）, which sit on top ofthe kidneys （肾）.
Over a 5-to 6-year period, dr. Sonia lupine andhis colleagues measures 24-hour cortisol levels in 51 healthy volunteers, mostwhom were in their 70s.
The researchers tested the volunteers' memoryon six people in the increasing/high category and five people in thedecreasing/moderate group. The groups did not differ in tests of immediatememory, but the increasing/high cortisol group had other memory problems comparedwith those in the decreasing/moderate group.
The researchers also found that the totalvolume of the hippocampus in those in the increasing/high group was 14% lowerthan those in the decreasing/moderate group, although there were no differencesin other brain regions.
The results suggest that "…brain aging can be accelerated by levels of adrenal hormones thatare not generally regarded as pathological（病态的） andthat variation within this normal range is related to variation in the rate ofbrain aging." write porter and landfield." This further suggests thatchronic stress may accelerate the worsening of the hippocampus.
6 which of the following plays a key role inone's learning and memory?
A the kidneys
B the adrenal hormone
C the stress hormone
D the hippocampus
7 when the levels of cortisol go high ,thehippocampus
A may expand
B may shrink
C may disappear
D may function better
8 according to the passage, when people areunder stress,
A the adrenal glands will produce cortisol
B the kidneys will shrink rapidly
C the hippocampus will produce cortisol
D the brain will work more efficiently
9 it app ears that when the hippocampus shrinkssue to high levels of cortisol, other brain regions
A may change dramatically
B may stop functioning
C may remain unaffected
D may be seriously damaged
10 the research conducted by porter and landfield showed that
A the levels of adrenal hormones have nothingto do with brain aging
B changes in the levels of adrenal hormones canaffect brain aging
C chronic stress may strengthen one's memory
D the rate of brain aging always remains stable
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