问题 问答题

促胃液素的生理作用及其分泌调节如何

答案

参考答案:

解析:促胃液素是由胃窦部粘膜和十二指肠粘膜的G细胞所分泌的一种胃肠激素。它的主要作用是:①促进胃酸分泌;②促进肝胆汁和小肠液的分泌;③促进胰酶和胰HCO3ˉ的分泌;④促进食管-胃括约肌的运动,促进胃运动及小肠运动,促进胆囊收缩;⑤促胃液素能刺激胃泌酸部位和十二指肠粘膜的蛋白质、RNA和DNA的合成,从而促进其生长。分泌调节:①迷走神经兴奋可引起胃窦粘膜内的G细胞释放促胃液素,后者经过血液循环刺激胃腺分泌;③食物的化学成分主要是蛋白质消化产物,可直接作用于G细胞,引起促胃液素的释放;③食物通过幽门部,可引起十二指肠释放促胃液素;④盐酸可直接抑制胃窦粘膜中的G细胞,减少促胃液素释放;⑤盐酸在胃内可引起胃粘膜释放生长抑素。其间接抑制促胃液素的释放。

单项选择题

Once upon a time, innovation at Procter & Gamble flowed one way: from the United States outward. While the large Cincinnati-based corporation was no stranger to foreign markets, it usually sold them products that were already familiar to most Americans. Many Japanese families, for instance, swaddle their babies in Pampers diapers, and lots of Venezuelans brush their teeth with Crest. And of course (company executives assumed) Americans at home wanted these same familiar, red white-and-blue brands. We might buy foreign-made cars, or chocolates, or cameras—but household cleaners and detergents.9

Recently, however, P&G broke with this long-standing tradition. Ariel, a P&G laundry detergent, was born overseas, and is a familiar sight on store shelves in Europe and Latin America. Now bilingual packages of Ariel Ultra, a super-concentrated cleaner, are appearing on supermarket shelves in Los Angeles.

Ariel’s appearance in the United States reflects demographic changes making Hispanics the nation’s fastest-growing ethnic group. Ariel is a hit with this population. In fact, many Mexican immigrants living in southern California have been " importing" Ariel from Tijuana, Mexico. "Hispanies knew this product and wanted it," says P&G spokeswoman Marie Salvado. "We realized that we couldn’t convince them to buy our other laundry detergents. " P&G hopes that non-Hispanic consumers will give Ariel a try too.

Ariel’s already p presence in Europe may provide a springboard for the company to expand into other markets as well. Recently P&G bought Rakona, Czechoslovakia’s top detergent maker. Ariel, currently a top seller in Germany, is likely to be one of the fast new brands to appear in Czech supermarkets. And Ariel is not tile only foreign idea that the company hopes to transplant back to its home territory. Cinch, an all-purpose spray cleaner similar to popular European products, is currently being test-marketed in California and Arizona. Traditionally Americans have used separate cleaners for different types of surfaces, but market research shows that American preferences are becoming more like those in other countries.

Insiders note that this new reverse flow of innovation reflects more sweeping changes at Procter & Camble. The firm has hired many new Japanese, German, and Mexican managers who view P&G’s business not as a one-way flow of American ideas, but a two-way exchange with other markets. Says Bonita Austin of the investment fin Wertheim Schroeder, " When you met with P&G’s top managers years ago, you wouldn’t have seen a single foreign face; today, they could even be in the majority. "

As Procter & Gamble has found, the United States is no longer an isolated market. Americans are more open than ever before to buying foreign-made products and to selling U S-made products overseas.

According to the text, Procter & Gamble hopes to transplant foreign idea back to its home territory because()

A. Americans are more likely to buy foreign-made products than before

B. for most Americans foreign products are much more attractive than home-made ones

C. foreign-made products are superior to home-made ones in terms of quality

D. the company has hired more foreigners in its top management than before

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