英语听力文摘 English Digest 697 婴儿的心率应该是多少呢？

Heart Rate: What A Baby’s Heart Rate Should Be

Picture new parents cooing at their baby on the couch. The baby’s quiet and calm, and everyone’s at rest. So their heart rates are low, maybe 60 or 70 beats a minute for the adults. What about the baby? How do you think the baby’s heart rate compares to the parents’?

Baby Bliss¹

Newborns have resting heart rates around 100 to 150 beats per minute, way higher than that of adults. In fact, a newborn’s resting heart rate is in the ballpark of the target heart rate for an adult doing a heavy workout. What gives? Why do newborns’ hearts beat so much faster than adults’?

Part of the answer lies in the fact that babies grow so dramatically. They burn food in every cell of their bodies to fuel that growth.

The process requires not only an abundance of milk but also oxygen, and it produces large amounts of carbon dioxide as waste.

Babies’ hearts work overtime² to keep supplying oxygen and removing carbon dioxide to fuel their amazing growth.

The Animal World

But growth isn’t the only factor, because it’s not just baby animals we’re talking about. Adult Chihuahuas have much higher heart rates than adult elephants. Why? Chihuahuas have a greater surface to volume ratio. In other words, the Chihuahua has a greater proportion of skin than internal tissue, which means it loses more heat to the environment, relatively³ speaking, than a larger animal.

Babies’ hearts beat much faster than their parents’, both to fuel their growth and make up for greater heat loss to the environment.

So little hearts maintain a higher metabolic⁴ rate, pound for pound, than big hearts.

心率：婴儿的心率应该是多少

想象一下新父母在沙发上对着孩子咕咕叫的情景。婴儿安静、平静，每个人都在休息。因此，他们的心率很低，成年人可能每分钟心跳60到70次。那婴儿呢？你认为婴儿的心率与父母的相比如何？

宝贝幸福

新生儿的静息心率约为每分钟100至150次，远高于成人。事实上，新生儿的静息心率与成人进行剧烈运动时的目标心率接近。有什么好处？为什么新生儿的心跳比成年人快得多？

部分原因在于婴儿的成长如此迅速。他们在身体的每一个细胞中燃烧食物以促进生长。

这个过程不仅需要大量的牛奶，还需要氧气，而且会产生大量的二氧化碳作为废物。

婴儿的心脏加班加点地工作，不断地提供氧气和清除二氧化碳，以促进他们惊人的成长。

动物世界

但增长并不是唯一的因素，因为我们谈论的不仅仅是小动物。成年吉娃娃的心率比成年大象高得多。为什么？吉娃娃的表面积与体积比更大。换言之，吉娃娃的皮肤比内部组织的比例更大，这意味着相对而言，它比更大的动物向环境释放的热量更多。

婴儿的心跳比他们的父母快得多，这既是为了促进他们的成长，也是为了弥补环境中更大的热量损失。

因此，小心脏比大心脏保持更高的代谢率。

1 bliss   

n.狂喜，福佑，天赐的福

参考例句：

• It's sheer bliss to be able to spend the day in bed.整天都可以躺在床上真是幸福。
• He's in bliss that he's won the Nobel Prize.他非常高兴，因为获得了诺贝尔奖金。

2 overtime   

adj.超时的，加班的；adv.加班地

参考例句：

• They are working overtime to finish the work.为了完成任务他们正在加班加点地工作。
• He was paid for the overtime he worked.他领到了加班费。

3 relatively   

adv.比较...地，相对地

参考例句：

• The rabbit is a relatively recent introduction in Australia.兔子是相对较新引入澳大利亚的物种。
• The operation was relatively painless.手术相对来说不痛。

4 metabolic   

adj.新陈代谢的

参考例句：

• Impressive metabolic alternations have been undergone during embryogenesis.在胚胎发生期间经历了深刻的代谢变化。
• A number of intoxicants are associated with metabolic acidosis.许多毒性物质可引起代谢性酸中毒。