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SAMPLE 13 [医学类] 题目序号 题型归类 第1题 中心主旨题型 第2题 审题定位题型 第3题 细节推导题型 第4题 句间关系题型 第5题 细节推导题型 Until about five years ago, the very idea that peptide hormones might bemade anywhere in the brain besides the hypothalamus was astounding. Peptidehormones, scientists thought, were made by endocrine glands and thehypothalamus was thought to be the brains only endocrine gland. What ismore, because peptide hormones cannot cross the blood-brain barrier,researchers believed that they never got to any part of the brain other thanthe hypothalamus, where they were simply produced and then released into thebloodstream. But these beliefs about peptide hormones were questioned as laboratoryafter laboratory found that antiserums to peptide hormones, when injected intothe brain, bind in places other than the hypothalamus, indicating that eitherthe hormones or substances that cross-react with the antiserums are present.The immunological method of detecting peptide hormones by means of antiserums,however, is imprecise. Cross-reactions are possible and this method cannotdetermine whether the substances detected by the antiserums really are thehormones, or merely close relatives. Furthermore, this method cannot be used todetermine the location in the body where the detected substances are actuallyproduced. | 
