阿司匹林在人体内的代谢过程丨医学英语视听学习

Aspirin Journey through the body

阿司匹林在人体内的代谢过程

After swallowing an aspirin tablet, it will go on a journey through your digestive system.

阿司匹林片被吞下后，将通过消化系统。

Absorption 

药物吸收

The tablet will travel down the esophagus into the stomach where it is dissolved into much smaller particles. These particles will continue their journey into the small intestine where most of them will be absorbed into the blood.

药片将沿食管向下，进入胃，在胃内溶解成更小的颗粒。这些颗粒将继续向下进入小肠，大多数小颗粒在小肠内被吸收入血液。

The small intestine walls, also called lumina are lined with tiny villi which stick out to provide a large surface area for the nutrients inside the food to be absorbed.

小肠壁，或小肠管腔内有微小的绒毛，它们伸出，为吸收食物营养提供较大的表面积。

Looking closer at these villi, you can see they have a rich blood supply and are covered in a thin layer of epithelial cells. The aspirin molecules will work their way through the epithelial cells and into the bloodstream where they are carried around the body. 

仔细观察这些绒毛，可以发现，它们有丰富的血供，由一层薄薄的上皮细胞构成。阿司匹林分子通过上皮细胞进入血流，在全身循环。

Distribution

药物分布

Blood plasma contains complex molecules called albumin. 

血浆含有称为白蛋白的复杂分子。

Albumin is a protein made by the liver which transports nutrients around the body. Albumin also binds to drugs that enter the bloodstream.

白蛋白是一种在肝脏内合成的蛋白质，可以将营养物质运输到全身。白蛋白也与进入血流的药物结合。

Here you can see some of the aspirin molecules binding to the albumin.

在这里，你可以看到一些与白蛋白结合的阿司匹林分子。

All the aspirin particles that have been bound will be filtered out as they pass through the liver and only the remaining aspirin molecules will get through and have any effect on the body.

所有与白蛋白结合的阿司匹林颗粒都将在通过肝脏时过滤，只有剩余的阿司匹林分子成功在身体内发挥作用。

Different drugs will bind to albumin in different amounts depending on their affinity for plasma protein. 

由于对血浆蛋白的亲和力不同，不同药物与白蛋白结合的量也不同。

The next stop on the journey is the liver. The aspirin-rich blood will enter the liver through the hepatic portal vein at the bottom and it will exit at the top via the hepatic vein. 

接下来，阿司匹林颗粒进入肝脏。富含阿司匹林的血液将通过底部的肝门静脉进入肝脏，通过顶部的肝静脉流出。

At this stage, even more of the aspirin will be removed through a process called first pass metabolism. 

在这一阶段，更多阿司匹林将通过“首过代谢”的过程消除。

The livers' job is a bit like a filter. It will metabolize drugs before they reach the rest of the body. 

肝脏的作用有些类似于过滤器。药物将先通过肝脏代谢，然后到达身体其他部位。

It does this in a few steps. 

药物在肝脏内的代谢分为多个步骤。

Phase 1 Metabolism.

Ⅰ相代谢反应

First aspirin is hydrolyzed breaking off ethanoic acid and leaving behind salicylic acid. This salicylic acid isn't water-soluble, so it can't be excreted in urine yet. 

首先，阿司匹林被水解，生成乙酸和水杨酸。水杨酸不溶于水，因此不能随尿液排泄。

Phase 2 Metabolism. 

Ⅱ相代谢反应

An ionized group is then added to the salicylic acid forming glucoronide which is water-soluble and can be excreted in urine.  A lot less of the aspirin will continue its journey onto the rest of the body including the site of the pain.  

然后，离子基团加水杨酸，形成葡萄糖醛酸，葡萄糖醛酸溶于水，可以随尿液排泄。此时，更少的阿司匹林将继续到达身体其他部位，包括疼痛区。

Only 68% of orally-taking aspirin will have any effect at all because of all the filtering that the body has done. This percentage is called the drugs oral bioavailability. 

由于身体的过滤作用，仅 68% 口服的阿司匹林发挥作用。这个百分比是口服药物的生物利用度。

If drugs are not administered orally, eg. intravenously or buccally, then they can bypass the small intestine and live, so none of this filtering takes place and they are 100% bioavailability. 

如果不是口服给药，而是静脉或经颊给药等，那么，药物将绕过小肠和肝脏，不发生过滤，生物利用度将达到 100%。

We are now at the site to some skin tissue damage. Tissues in the skin are creating prostaglandins which are causing inflammation. The prostaglandins are sending messages to the nerves in the skin responsible for the sensation of pain. 

现在，我们看到的是一些受损的皮肤组织。皮肤组织产生引起的炎症的前列腺素。前列腺素向负责疼痛感觉的皮肤神经发送信息。

Once the aspirin arrives in the blood supply at the site, it prevents the production of prostaglandins in the tissue, which will reduce the swelling and stop the messages being sent to the nerves that transmit the pain.

阿司匹林随血供到达该部位时，将阻止组织产生前列腺素，从而减轻肿胀，中断向痛觉神经发送信号。

Excretion

药物排泄

Any remaining aspirin in the blood will go round and round the blood supply, going back through the liver several times until it is all used up or filtered out of the body.  It traveled into the kidneys and then into the bladder for excretion.

血液中残留的所有阿司匹林随着血流周而复始地循环，它们多次通过肝脏，直至全部吸收或过滤殆尽。它将进入肾脏，然后是膀胱，随后排泄出去。