And the nephrons have to figure out what to do with them.

肾元要搞清楚 如何处理它们。

The kidney does this by the processes of filtration, reabsorption, and secretion in the nephron.

肾脏依靠肾单位过滤、重吸收、分泌等过程行使能。

Nephrons are mostly a series of tubes attached end-to-end that move fluids and wastes towards the bladder.

肾单位主要由大量肾小管组成，最终将水和代谢废物引入膀胱。

The nephrons in the kidneys are the structures that physically control how much water is excreted from your body.

肾脏中的肾单位是控制体内排出水分多少的组织结构。

In kidney failure, the nephron doesn't effectively reabsorb calcium, which allows it to get excreted into the urine.

当肾衰竭时，肾单位不能有效重吸收钙，这使得钙离子可以排入尿液。

The blood goes into the kidneys via the renal arteries, it is then forced into a million small filtering units called nephrons.

血液通过肾脉进入肾脏，然后被迫进入一百万个小型过滤单元，称为肾小球。

Once millions of nephrons have each made urine, it flows into the minor calyces, then major calyces, and finally into the renal pelvis.

当数以百万计的肾单位各自都产生尿液，尿液便流入肾小盏，然后是肾大盏，最终进入肾盂。

The epithelium of the nephron is made of specialized cells called podocytes which wrap around the basement membrane like the tentacles of an octopus.

肾单位的内皮细胞由特殊的细胞组成，称为足细胞；足细胞足鱼触手一样包裹着基底膜。

A narrow lumen means less blood and oxygen gets delivered to the kidney, resulting in ischemic injury to the nephron's glomerulus.

管腔狭窄意味着对肾的供血供氧减少，导致肾单位中肾小球的缺血性损伤。

And at this point the distal tubule and collecting ducts of the nephron can either reabsorb or secrete potassium depending on what the body needs.

这时，远曲小管和肾单位导管会根据需要重吸收或者分泌钾离子。

Now, before we dive too far in here, let's re-draw the nephron so that the structure of the renal tubule is a little more accurate.

现在，趁还没有学得更深，我们来画一个肾单位，让肾小管的结构更加精确。

Within each kidney, there are about 1 million nephrons, and each nephron is made up of a renal corpuscle and a renal tubule.

每个肾约有100万个肾单位，每个肾单位由肾小体、肾小管组成。

Over many years, this process of glomerulosclerosis, once again, diminishes the nephron's ability to filter the blood and leads to chronic kidney disease.

多年后，这一肾小球硬化的过程，也会降低肾单位的血液滤过能力，导致慢性肾病。

Normally, calcium filters from the blood into the glomerulus of the kidney but is then reabsorbed back into the blood by the nephron so that it isn't lost.

正常情况下，钙从血液中过滤进入肾小球，但随后被肾单位重新吸收到血液中，以防丢失。

This excessive extracellular matrix leads to glomerulosclerosis, hardening and scarr, and diminishes the nephron's ability to filter the blood - over time leading to chronic kidney disease.

这些多余的细胞外基质造成肾小球硬化症，即肾小球硬化、瘢痕化，并减弱肾单位对血液的滤过能力，逐渐发展成慢性肾病。

To make this exchange as efficient as possible, some organisms have evolved specialized exchange surfaces like the alveoli in the lungs or root hairs and plants, or the nephrons and kidneys.

为了使这种交换尽可能高效，一些生物体进化出了专门的交换表面，比如肺泡、根毛和植物，或者肾上腺和肾脏。

Aldosterone is secreted in response to elevated levels of renin, and it's role is to bind to receptors on two types of cells along the distal convoluted tubule of the nephron.

肾素水平升高可刺激醛固酮的分泌，后者的作用是结合肾远曲小管中两种细胞上的受体。

The glomerular filtrate is not the same consistency as urine, as much of it is reabsorbed into the blood as the filtrate passes through the tubules of the nephron.

肾小球滤液与尿液的浓度不同，当滤液通过肾小管时，大部分被重新吸收到血液中。

And this is called forced diuresis and it essentially overwhelms the proximal convoluted tubule of the nephron with so much fluid that it's unable to effectively reabsorb solutes, including phosphate.

这叫强迫利尿，它会使近曲小管充盈大量液体，以至于不能有效地重新吸收溶质，包括磷酸盐。

These two make their way to the nephron of the kidney, and at this point in the proximal convoluted tubule, phosphate usually gets reabsorbed back into the blood via sodium-phosphate cotransporters.

随着这一对离子进入肾脏的肾单位之中，在近曲小管处，磷酸盐通常被重新吸收，经由钠-磷协同转运蛋白重新入血。