人体解读：红血球

外科手术基本都需要输血，让我们一起来了解一下血液中的红血球。

Gabriel Weston 

作者：Gabriel Weston 

Surgeons have a more intimate relationship with blood than most. We dread losing too much of the stuff, and we often get covered in it. Last week, while operating on a patient under local anaesthetic, I cut through a vessel and ended up with two stripes across my face. It's no wonder that I have always been fascinated by red blood cells, or erythrocytes.

外科是和血液打交道最多的。在外科手术中，为保证手术的成功，经常需要为病患输血。在上周的一个局麻手术中，就为病患提供输血，手术才得以成功。这并不是说医生偏好术中输血。

If you press firmly on one of your fingernails and then release the pressure, the nail-bed will blanch momentarily before pinking up again; it's a simple test used to assess perfusion – the extent to which tissues are adequately oxygenated. And it is the red blood cell that is responsible for this critical job.

按压一会指甲再放开，会发现指甲先变白，然后又恢复粉红的血色。这算是简单的评估血氧饱和度的小实验。所谓血氧饱和度就是组织中的氧结合量指标。红血球的职能就是和氧气结合，与氧气结合的红血球是鲜红色的。

When levels of oxygen in a person's tissue decrease – for example from exercise, trauma or disease – the kidney releases a hormone called erythropoietin. This stimulates the production of new red blood cells. Just as they are about to enter the circulation, the cells lose their nucleus making them incredibly light and bendy, and giving them their characteristic biconcave shape. By folding up like tiny umbrellas, they are now able to fit through the narrowest of capillaries, and so deliver essential oxygen.

人体组织中的氧气含量下降时，如做运动，受伤或生病时，肾脏会产生促红细胞生成素。这种激素能刺激机体制造新的红血球。红细胞在进入人体循环之前，会经历一次去细胞核的变化过程，以减轻自身重量并提高其柔韧性，去核后的红血球中部向内凹陷呈双凹圆盘状。鲜红球像折叠起来的小伞一样，可以穿行于人体的毛细血管中，向身体传送氧气。

Red blood cells contains large amounts of haemoglobin – the protein that gives blood both its colour and its oxygen-binding capacity. Each one lives for about a 120 days and travels an amazing 300 miles around the body.

红血球含有大量的血红素，这种蛋白质能和氧气结合并是血液呈现出红色。每个红血球能存活120天，终其一生要完成300英里的人体旅行，这是不是很神奇？