问题 问答题 简答题

简述骨骼肌兴奋-收缩耦联过程及收缩舒张原理。

答案

参考答案:

骨骼肌兴奋-收缩耦联过程及收缩舒张原理如下:

肌膜动作电位经横管传到细胞内部→信息通过三联体结构传给肌浆网终池→终池释放Ca离子→肌浆中Ca离子增多→Ca离子与肌钙蛋白结合→肌钙蛋白构型改变→原肌凝蛋白构型改变→暴露肌纤蛋白(即肌动蛋白)上的横桥结合位点→横桥与肌纤蛋白结合→激活ATP酶,分解ATP供能→横桥扭动,拖动细肌丝向M线滑动→肌小节缩短→肌肉收缩。

肌膜动作电位消失→肌浆网膜上钙泵转运,Ca离子被泵回肌浆网→肌浆中Ca离子降低→Ca离子与肌钙蛋白分离→肌钙蛋白构型复原→原肌凝蛋白复位→遮蔽肌纤蛋白上的横桥结合点→阻止横桥与肌纤蛋白结合→细肌丝从粗肌丝中滑出,肌小节恢复原位→肌肉舒张。→肌浆中Ca离子增多→Ca离子与肌钙蛋白结合→肌钙蛋白构型改变→原肌凝蛋白构型改变→暴露肌纤蛋白(即肌动蛋白)上的横桥结合位点→横桥与肌纤蛋白结合→激活ATP酶,分解ATP供能→横桥扭动,拖动细肌丝向M线滑动→肌小节缩短→肌肉收缩。

肌膜动作电位消失→肌浆网膜上钙泵转运,Ca离子被泵回肌浆网→肌浆中Ca离子降低→Ca离子与肌钙蛋白分离→肌钙蛋白构型复原→原肌凝蛋白复位→遮蔽肌纤蛋白上的横桥结合点→阻止横桥与肌纤蛋白结合→细肌丝从粗肌丝中滑出,肌小节恢复原位→肌肉舒张

单项选择题
单项选择题

Middle born children will tell you that they usually didn’t feel all that special while growing up. The first born had his spot-carrier of the family banner and responsible for everything. The last born had his comfy little role, but the middle born had no distinctive place to call his own.

Middle-borns just seem to be easily overlooked, and maybe that’s why there are so few pictures of them in the family photo album. There may be hundreds, seemingly thousands, of pictures of the firstborn. For some strange reason, however, which I have confirmed by polling middle-born children around the world, there are seldom many pictures of the middle child, and what photos there are have him included with the others -- squeezed again between the older sibling and the younger sibling.

Another thing that can be said of many middle-born children is that they typically place great importance on their peer group. The middle child is well known for going outside the home to make friends faster than anybody else in the family. When a child feels like a fifth wheel at home, friends become very important; as a result, many middle children (but not all, of course) tend to be the social lions of the family. While firstborns, typically, have fewer friends, middle children often have many.

Middle children have a propensity to leave home first and live farther away from the family than anyone else. I observed a dramatic illustration of this tendency while I was a guest on Oprah Winfrey’s show. The subject that day was sibling rivalry. Three charming young women, all sisters, were among the guests, and we quickly learned that the firstborn and the last born were residents of the Eastern state where they had grown up. They had settled down near their parents and other family members. But the middle child had moved to the West Coast.

I suppose she could have gotten another two thousand miles farther away by moving to Hawaii, but her point was still well made. Middle children are the ones who will most often physically distance themselves from the rest of the family. It’s not necessarily because they’re on the outs with everyone else. They simply !ike to do their own thing, make their own friends, and live their own lives.

All of this is not to say that middle children totally ignore their siblings or the rest of the family. one common characteristic of the middle child is that she is a good mediator or negotiator. She comes naturally into this role because she’s often right in the middle, between big brother and little sister, whatever the case may be. And because she can’t have Mom or Dad all to herself, she learns the fine art of compromise. Obviously, these skills are assets in adult life, and middle children often become the best adjusted adults in the family.

How did the author get to know that middle children have fewer pictures in the family photo album?()

A.Form the complaints of middle children.

B.Form his own family situation.

C.By asking a lot of middle children.

D.By going to Oprah Winfrey’s show.