心动周期中，心室血液的充盈主要取决于
A．心房收缩的挤压作用
B．胸内负压促进静脉血回流
C．心室舒张时的“抽吸”作用
D．骨骼肌活动的挤压作用
E．血液的重力作用
参考答案：C
解析：在心室舒张期，心室内压下降低于心房内压时。房室瓣开放，血液从心房流入心室使心室充盈。心室的充盈主要依靠心室舒张造成的室内压大幅下降的“抽吸”作用。心房收缩增加心室舒张末期容积和压力约占25%。
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| Living and dealing with kids can be a difficult job, but living and dealing with parents can be even more difficult. If I have learned anything in my 16 ears, it is that 1 is very important, 2 when you disagree. With any relationship, you need to let other people know how you're 3 . When you're mad at your parents, or anyone else, not talking to them doesn't 4 anything. Communication 5 the concerns (所关注的事) of another. It means that you can't 6 come home from school, go up to your room and ignore (不理睬) everyone. 7 you just say "Hi", and see how their day was for five minutes, it is better than nothing. When 8 with parents, you always have to make them feel good about how they are doing 9 parents. If you are 10 to make them see something as you see it, tell that you'll listen to what they have to say, but ask them 11 to listen to you. Shouting or walking away only makes the situation 12 . This is an 13 : one night, Sophie went to a street party with her friends. She knew she had to be home by 14 , but she didn't feel she could jus 15 to go home. That would be rude. 16 , the had been nice enough to make her along with them. Needless to say, she was late getting home. Her parents were 17 at first, but when Sophie explained why she was late, they weren't as mad and let the incident go. Communication was the key factor here. If Sophie's parents had not been willing to 18 , Sophie would have been in a lot of trouble. Communication isn't a(n) 19 way deal, it goes both ways. Just remember, if you get into a 20 like Sophie's, tell the other person how you feel-listening is a key factor in communication. | ||||
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