Parts of a nephron Learn about the 5 major parts of the kidney's nephron. Rishi is a pediatric infectious disease physician and works at Khan Academy.
Parts of a nephron
- I'm gonna draw for you two of the most important organs in the body.
- They're on the left and right side of the body and look pretty much like that.
- They look like kidney beans and that's what they are, they're kidneys.
- So we have some arteries, the renal arteries, that flow into them.
- And renal is just a word referring to kidneys.
- And we've got renal veins with blood flowing back out of them.
- Once the blood is headed back to the heart, we call it renal vein.
- And there are two of them.
- The most important part of these kidneys, certainly the part that makes them unique,
- is that they have these ureters.
- And these ureters drain urine into a bladder.
- I'm gonna draw that right here, that's the bladder.
- The ureters are the third tube coming out of our kidney.
- When you're ready to urinate you can release all that urine from your bladder into the outside world.
- There's three basic things that I want you to remember coming into or out of kidneys.
- The renal arteries, the renal veins and the ureters.
- To really make sense of it, you gotta think about how the artery might split up.
- So we go back to the artery and we follow it.
- It starts kind of branching into five little branches, it might have more branches out of those branches,
- and finally maybe even some more branches, eventually it's not even an artery anymore, right?
- All these little branches are so tiny, you would call them arterioles.
- Let's just take this arteriole, this little guy and let's see what happens.
- So let's take that little guy and show you on the left side of the screen what he looks like.
- Let's look at this arteriole a little bit closer.
- This is our Afferent arteriole.
- It's called afferent because it's headed towards something. Afferent arteriole.
- Don't forget where it comes from, it's coming from the renal artery.
- The blood is coming from the renal artery and it's headed towards something and that's this.
- The artery or the arteriole rather starts making a lot of little turnbacks on itself and finally straightens out.
- When it does it's called the Efferent arteriole.
- That's how we keep straight whether it's coming or going from this little network of blood vessels.
- This little network of blood vessels, if you look under a microscope, is actually being hugged by something like this.
- This is the first time we're taking a look at something that isn't a blood vessel in the kidney,
- it begins our journey of urine.
- This thing is called the Bowman's capsule, this is the thing in yellow I've drawn for you.
- Whenever things are named like this, you have to wonder 'Who was mister Bowman?'
- Mister Bowman, turns out, was from England, actually he was a very curious fellow.
- So he looked under a microscope and he noticed that, if you look right where the little cups of blood vessels are,
- you can actually see that there's something surrounding them, each of them. So he called that Bowman's capsule.
- And that's what we still call it today.
- England was laying claim on parts of the kidney anatomy, we might not even have known then.
- So that's Bowman's capsule.
- That's the first part of the nephron. I'll actually show you all the parts of the nephron.
- The next part of the nephron, nephron just means kind of the unit of the kidney we care about.
- The next part is looking really squiggly, very convoluted, right?
- I'm trying to draw it that way purposefully, because I want you to remember it's called the proximal,
- because it's near the Bowman's capsule, thus proximal, convoluted tubule.
- Because this is one long tubule, like a little tube.
- This is the proximal convoluted tubule, the part of the nephron after Bowman's capsule is the proximal convoluted tubule.
- Then it gets into a long deep loop, long loop like that that.
- This loop is called the loop of Henle.
- You're seeing now part three is called the loop of Henle.
- Loop makes sense, but 'of Henle'?
- You've got to wonder again 'Is this another British guy, who's mister Henle?'
- Mister Henle, turns out, is actually not British, he's from another part of Europe,
- maybe you can guess before I finish this drawing.
- He discovered that if you follow the nephron deep into the middle of the kidney,
- it has this little loops, very delicate loops, but very important in helping urine form.
- He was a German scientist. If the British are going to identify something, so will the Germans.
- We still call that the loop of Henle.
- After the loop of Henle we have another area that is very convoluted.
- You can guess how we'll call this.
- When we call things, we try to stay consistent,
- If the first part was called the proximal convoluted tubule,
- we would call this not the proximal, because it's not near anymore, but a little further away,
- we call this the distal, meaning further away, convoluted, 'cause it's still convoluted, tubule.
- This is the distal convoluted tubule.
- Finally there's a fifth part of all this, the fifth part of this is a giant tube of collection.
- All this stuff goes to a collection tube.
- I'm actually showing you where all the other distal convoluted tubes might be dumping in as well.
- Eventually all this stuff is gonna go to the same place, which is down to the ureter.
- We've seen now how things go to the ureter.
- You can see how things come from the renal artery, but you're probably still wondering,
- (oh, I see I didn't label this for you, this is the collecting tube)
- You're probably still wondering 'Where is the renal vein in all this?'
- I still drew the efferent arteriole as being red, it has oxygen.
- Where does the venous blood come from?
- The answer is right here, so you basically get red blood, oxygenated blood, flowing over all these parts of the tubule.
- Oxygenated blood.
- The proximal convoluted tubule, the loop of Henle, the distal convoluted tubule, all get wonderful blood.
- Finally, when all that is set and done, it all drains into one thing, one final renal vein.
- And that's with all of the blood coming together.
- This little network of capillaries are considered the peritubular, going around the tubule, peritubular capillaries.
- That makes sense.
- You can see the renal artery blood coming in, going through the afferent arteriole, the efferent arteriole,
- draining back into the peritubular capillaries and finally the renal vein.
- This important structure in yellow that I've drawn, has five parts to it.
- All five parts together are called the nephron.
- This is an important structure and we'll talk about the different parts of the nephron in future videos.
- This is an important structure, at least you'll get a sense of what it looks like and what the different parts are called.
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