These parasympathetic neurons make the rectum contract and the internal anal sphincter relax.

这些副交感神经元可以使直肠收缩，并使肛门内约肌松弛。

During life's three billion-plus year journey on Earth, anal evolution happened independently many times in different branches of life.

在生命在地球上 30 亿多年的旅程中，肛门进化在不同的生命分支中独立发生了许多次。

The gastrointestinal tract is made up of the mouth, pharynx, esophagus, stomach, small intestine, large intestine, and finally the anal canal.

消化道的构成包：口腔、咽、食管、胃、小肠、大肠以及肛管。

Symptoms of cauda equina include decreased bowel and bladder control due to a decreased tone of anal sphincters and muscle wall of the bladder and decreased sexual function.

马尾神经综合征的症状，包和膀胱控制能力；这是由于肛门约肌和膀胱壁肌肉力下降引起的，以及性功能下降。

Fart also has a relative in Ancient Greek  and that brings us on to one of the many clandestine anal excretions buried  in our language: the word partridge.

放屁在古语中也有“亲戚”，这让我们想到了隐藏在我们的语言中的众多秘密肛门泄物之一：鹧鸪这个词。

Meanwhile, signals are sent to the brainstem and thalamus, and when these decide the right moment has come, they allow the external anal sphincter to relax - and feces goes, hopefully, into the toilet bowl.

直肠发出的信号同时也发送到了脑干和丘脑；当它们认定“时机成熟”时，会下达指令使肛门外约肌松弛；粪就能——不出意外的话——顺利入马桶。

So, for instance, there's no evidence that oral and anal characteristics, the personality characteristics I talked about – about being needy versus being stingy – relate in any interesting way to weaning or toilet training.

因此，例如，没有证据表明口腔和肛门的特征，我谈到的性格特征——关于需要和吝啬——以任何有趣的方式与断奶或如厕训练相关。

Just the anal vampire who can't stand mess and wants everything to be structured and needs to have a regiment and has to make a chore wheel so that everyone keep on top of doing the dishes or vacuuming.

只有肛门吸血鬼无法忍受混乱，望一切都井井有条，需要有一个团，必须做一个家务轮子，这样每个人都能继续洗碗或吸尘。

If it starts to rot, or you start to snack on this body, you'll have to cover the stench of decomposition with your own anal secretions so that other hungry, desperate, overworked parents don't come looking for your lunch.

如果它开始腐烂， 或者你开始在这个身体上吃零食，你就必须用你自己的肛门分泌物来掩盖腐烂的恶臭， 这样其他饥饿、绝望、过度劳累的父母就不会来找你的午餐了。