The belief that the mind plays an important role in physical illness goes back to the earliest days of medicine. From the time o

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问题     The belief that the mind plays an important role in physical illness goes back to the earliest days of medicine. From the time of the ancient Greeks to the beginning of the 20th century, it was generally accepted by both physician and patient that the mind can affect the course of illness, and it seemed natural to apply this concept in medical treatments of disease. After the discovery of antibiotics, a new assumption arose that treatment of infectious or inflammatory disease requires only the elimination of the foreign organism or agent that triggers the illness. In the rush to discover new antibiotics and drugs that cure specific infections and diseases, the fact that the body’s own responses can influence susceptibility to disease and its course was largely ignored by medical researchers.
    It is ironic that research into infectious and inflammatory disease first led 20th-century medicine to reject the idea that the mind influences physical illness, and now research in the same field—including the work of our laboratory and of our collaborators at the National Institutes of Health—is proving the contrary. New molecular and pharmacological tools have made it possible for us to identify the intricate network that exists between the immune system and the brain, a network that allows the two systems to signal each other continuously and rapidly. Chemicals produced by immune cells signal the brain, and the brain in turn sends chemical signals to restrain the immune system. These same chemical signals also affect behavior and the response to stress. Disruption of this communication network in any way, whether inherited or through drugs, toxic substances or surgery, exacerbates the diseases that these systems guard against: infectious, inflammatory, autoimmune and associated mood disorders.
    The clinical significance of these findings is likely to prove. They hold the promise of extending the range of therapeutic treatments available for various disorders, as drugs previously known to work primarily for nervous system problems are shown to be effective against immune maladies, and vice versa. They also help to substantiate the popularly held impression(still discounted in some medical circles)that our state of mind can influence how well we resist or recover from infectious or inflammatory diseases.
    The brain’s stress response system is activated in threatening situations. The immune system responds automatically to pathogens and foreign molecules. These two response systems are the body’s principal means for maintaining an internal steady state called homeostasis. A substantial proportion of human cellular machinery is dedicated to maintaining it.
    When homeostasis is disturbed or threatened, a repertoire of molecular, cellular and behavioral responses comes into play. These responses attempt to counteract the disturbing forces in order to reestablish a steady state. They can be specific to the foreign invader or a particular stress, or they can be generalized and nonspecific when the threat to homeostasis exceeds a certain threshold. The adaptive responses may themselves turn into stressors capable of producing disease. We are just beginning to understand the many ways in which the brain and the immune system are interdependent, how they help to regulate and counterregulate each other and how they themselves can malfunction and produce diseases.
According to the passage, in order to maintain an internal steady state called homeostasis, ______.

选项 A、sometimes the stress response needs to go to the extreme
B、the stress response has to bar the foreign pathogens from the body
C、both the stress and immune responses need to be regulated
D、the immune system promotes physiological and behavioral changes

答案B

解析 根据文中最后一段的“When homeostasis is disturbed or threatened,a reper-toire of molecular,cellular and behavioral responses comes into play.These responses at—tempt to counteract the disturbing forces in order to reestablish a steady state.They can bespecific to the foreign invader or a particular stress, or they can be generalized and nonspe—cific when the threat to homeostasis exceeds a certain threshold.”可知,当体内平衡受到扰乱或遇到危险,分子、细胞和行为反应全都开始发挥作用。这些反应试图抵消那些干扰力量,以恢复稳定的状态。这些反应可能仅限于针对外来人侵者或特定的压力,当对体内平衡的威胁超越某个界限时,它们就扩大范围,不再有局限性。据此可知,为了维持人体内部的平衡,应激反应必须将外来病原体从体内消除。B项正确。
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