大学英语六级分类模拟题466
(总分467,考试时间90分钟)tiger mother
Part Ⅰ Writing
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1. Directions: For this part, you are allowed 30 minutes to write a short essay entitled Electronic Waste. You should write at least 150 words following the outlines given below in Chine:
1．废弃的电子产品越来越多；
2．如何正确处理这些电子产品。
influence Electronic Waste
Part Ⅱ Reading Comprehension
Section Abullied
How "Second Brain" Influences Mood and Well-Being
dictionary comA. As Olympians go for the gold in Vancouver, even the steeliest are likely to experience that familiar feeling of "butterflies" in the stomach. Underlying this nsation is an often-overlooked network of neurons (神经元) lining our guts that is so extensive some scientists have nicknamed it our "cond brain". A deeper understanding of this mass of neural tissue is revealing that it does much more than merely handle digestion or inflict the occasional nervous pang. The little brain in our gut, in connection with the big one in our head, partly determines our mental state and plays key roles in certain dias throughout the body.
沈阳外语培训学校B. Although its influence is far-reaching, the cond brain is not the at of any conscious thoughts or decision-making. "The cond brain doesn"t help with the great ligion, philosophy and poetry is left to the brain in the head," says Michael Gershon, chairman of the Department of Anatomy and Cell Biology at New York-Presbyterian Hospital/Columbia University Medical Centre, author of the 1998 book The Second Brain.
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C. Technically known as the enteric (肠的) nervous system, the cond brain consists of covers of neurons embedded in the walls of the long tube of our gut, which measures about nine meters end to end. The cond brain contains some 100 million neurons, Gershon says. This multitude of neurons in the enteric nervous system enables us to "feel" the inner world of our gut and its contents. Much of this neural **es to bear in the elaborate daily grind of digestion. Breaking down food, absorbing nutrients, and expelling of waste requires chemical processing, mechanical mixing and rhythmic muscle contractions that move everything on down the line.
D. Thus equipped with its own reactions and ns, the cond brain can control gut behavior independently of the brain, Gershon says. We likely evolved this intricate web of nerves to perform digestion and ejection "on site," rather than remotely from our brains through the middleman of the spinal cord (脊髓). "The brain in the head doesn"t need to get its hands dirty with the messy business of digestion, which is delegated to the brain in the gut," Gershon says. He and other rearchers explain, however, that the cond brain"s complexity likely cannot be interpreted through this process alone.
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E. "The system is way **plicated to have evolved only to make sure things move out of your bowel," says Emeran Mayer, professor of physiology, psychiatry and biobehavioral sciences at the David Geffen School of Medicine at the University of California, Los Angeles (UCLA). For example, scientists were shocked to learn that about 90 percent of the fibers in the primary gut nerve, the vagus (迷走神经), carry information from the gut to the brain and not the other way around. "Some of that information is decidedly unpleasant," Gershon says.
F. The cond brain informs our state of mind in other more obscure ways, as well. "A big part of our emotions are probably influenced by the nerves in our gut," Mayer says. Butterflies in the stomach—signaling in the gut as part of our physiological stress respon, Gershon says—is but one example. Although gastrointestinal (胃肠的)(GI) chaos can sour one"s moods, everyday emotional well- being may rely on messages from the brain below to the brain above. For example, electrical stimulation of the vagus nerve—a uful treatment for depression—may mimic the signals, Gershon says.
吸血鬼日记女主角G. Given the two brains" commonalities, other depression treatments that target the mind can unintentionally impact the gut. The enteric nervous system us more than 30 neurotransmitters, just like the brain, and in fact 95 percent of the body"s rotonin (血清素) is found in the bowels. Becau antidepressant medications called lective rotonin reuptake inhibitors (SSRIs) increa rotonin levels, it"s little wonder that meds (椎间盘镜) meant to cau chemical changes in the mind often provoke GI issues as a side effect. Irritable bowel syndrome—which afflicts more than two million Americans—also aris in part from too much rotonin in our guts, and could perhaps be regarded as a "mental illness" of the cond brain.
H. Scientists are learning that the rotonin made by the enteric nervous system might also play a role in more surprising dias: In a new Nature Medicine study published online February 7, a drug that inhibited the relea of rotonin from the gut counteracted the bone-deteriorating dia osteoporosis (骨质疏松症). "It was totally unexpected that the gut would regulate bone mass to the extent that one could u this regulation to cure osteoporosis," says Gerard Karnty, lead author of the study and chair of the Departmen
致辞是什么意思t of Genetics and Development at Columbia University Medical Centre.
I. Serotonin penetrating from the cond brain might even play some part in autism (孤独症), the developmental disorder often first noticed in early childhood. Gershon has discovered that the same genes involved in synap formation (突触形成) between neurons in the brain are involved in the digestive synap formation. "If the genes are affected in autism," he says, "it could explain why so many kids with autism have GI motor abnormalities in addition to elevated levels of gut-produced rotonin in their blood."
