Bilirubin: Recycling of Red Blood Cells – Composition of Bile (Nursing)

00:00 Bilirubin is the next one on our list but bilirubin, cholesterol, phospholipids remember, they're all end products of metabolism.

00:08 But I want to take on bilirubin.

00:11 This is a really specific part of the end product group.

00:16 Take a look at those red blood cells that you see in the graphic I have for you there.

00:20 Yeah. Those guys are done.

00:22 Their time is over. Their season is passed.

00:25 So I want to address what happens to old red blood cells.

00:30 They have a certain life span just like everything else and when they're old or they're broken down, the body does two things with them.

00:37 Parts of them are recycled and parts have to leave the body as waste.

00:42 So old red blood cells, when they're done and they're not useful anymore to the body, the body does two things with them.

00:50 It will recycle them and parts of them will leave the body as waste.

00:55 Okay, why do you care? Because this plays a really big role in assessment in what's going on in someone's body.

01:02 If the organs are not able to process this or they can't be recycled, if we can't get them to the waste site, we're going to have some real problems.

01:11 So our liver again, of course, the liver is a big part of it We're talking about bile and bilirubin.

01:18 We're going to look at how this happens.

01:19 See the liver breaks down old red blood cells - hemoglobin, and bilirubin is a waste product of this process.

01:28 So we know what bile is - it's got those six parts, but we're focusing on the bilirubin, part of the bile.

01:35 This comes from old red blood cells and it's a waste product of the process of redoing those red blood cells.

01:43 So on the picture there that is a giant Kupffer cell.

01:47 Now, Kupffer cell is in your liver and it's a phagocytic cell.

01:51 That means it...

01:54 It's gonna swallow something up.

01:57 So you see what that Kupffer cell or that phagocytic cell is doing to that worn out old red blood cell? Right. It's swallows it up so dead or damaged red blood cells are swallowed up by the phagocytic cells in the body that even includes the old liver Kupffer cells.

02:15 So that's what their job is.

02:16 These are the garbagemen of your body.

02:19 They noticed trash they pick it up and they swallow it up.

02:23 In this graphic, I've blown one of the red blood cells up so you can see what it would look like.

02:30 Now, we know there are four heme in each one of those, right? So you got a red one, an orange one, a bluish one, and a green one just to help that be solid in your mind.

02:39 Hemoglobin is an iron containing protein.

02:43 So if you're wondering what hemoglobin is when you draw lab work and you look at the hemoglobin and the hematocrit, that's what we're measuring.

02:50 Hemoglobin is an iron containing protein.

02:55 Now, this job of hemoglobin is when I breathe in, it takes oxygen and carries it from my lungs, carries it down to my cells, and it picks up carbon dioxide from my cells and brings it back up to oxygen.

03:10 So this is a critically important part of my body as most things are in your body.

03:17 So you've got the iron atom.

03:18 You've got the Heme and the globin.

03:20 All right. Now, I'm not done there.

03:23 Four heme groups are attached to the globin.

03:26 Okay, globin is made up of four polypeptide chains, and we've got them colored there.

03:31 Different colors for you.

03:33 I have a large graphic for you to help you understand how red blood cells go through recycling.

03:39 Now, I just want to reveal it one step at a time so it's easier to follow.

03:44 Once we walk through it step by step by step, you'll be fine, it'll all make sense.

03:49 So let's start in the upper left-hand corner.

03:52 I notice there are two blood cells there.

03:55 Right now, the lower one looks perfectly intact.

03:58 The top ones kind of chewed up.

04:01 Its days are done.

04:02 That's where we're going to start.

04:04 So let's start with a red blood cell that's old and done.

04:09 We know the first step in this process is that chewed up red blood cell is going to go through phagocytosis by a Kupffer cell.

04:17 It's going to be swallowed up.

04:19 Then it's going to be broken down into its four pieces, right? That is going to be turned into globin and heme, right? So when we break down the hemoglobin you're going to end up with globin and heme.

04:33 So you might want to write in their hemoglobin, right? That's what that is.

04:37 That's what we're looking, that for piece object.

04:40 We take that for piece object, the four different colors and we break it into the heme and the globin.

04:47 Okay, the globin is going to go to amino acids, but the heme is now the part we're going to follow.

04:55 So we started with an old red blood cell.

04:57 It experienced phagocytosis in the Kupffer cell.

05:00 It breaks it down in that phagocytotic process to give us the heme and the globin.

05:07 Globin, it's going to go into amino acids.

05:11 We've got your right there.

05:14 Heme is the piece we need to pick up.

05:17 Now, when bilirubin attaches to albumin you end up with unconjugated bilirubin.

05:25 So here's what happens in that process.

05:28 The unconjugated bilirubin goes to the the liver where the liver conjugates the bilirubin to make bile, stores it in the gallbladder.

05:38 Now, why do I care about conjugated or unconjugated? It's part of the reprocessing.

05:44 So old red blood cell, Kupffer cell, then it's turned into the - right, we've got the hemoglobin it breaks into the heme and the globin.

05:54 The heme is where the bilirubin attaches to albumin.

05:57 It's unconjugated bilirubin.

06:00 Then that moves over to the liver where its conjugated or transformed again.

06:05 It's reused in bile and it's stored in the gallbladder.

06:09 Now, what's the other path of the heme? Well, the heme part, the iron part of it, remember hemoglobin is an iron-based protein, it's transported to the bone marrow.

06:20 So heme goes one of two ways: we go the bilirubin route and re-circling that or you take the iron piece and it's transported to the bone marrow where the bone marrow makes more red blood cells.

06:34 That's why the second blood cell there, the lower one, is complete.

06:39 That's to remind you that we can take old red blood cells and make new ones.

06:43 We can take old red blood cells and be some building blocks of amino acids.

06:47 It takes old red blood cells and processes that in the bile.

06:52 Okay, that's a pretty amazing process.

06:55 So when you step back and look at the whole picture, probably be a good idea to pause your video right now, follow those steps and make sure they make sense to you.

07:08 Bilirubin is just broken down hemoglobin.

07:12 When I say broken down, it's gone through that process we just talked about.

07:16 You may want to keep that picture in front of you and keep comparing it as we walk through these again step by step.

07:22 Heme plus globin are separated.

07:25 So in hemoglobin, they're together and then see that stuff on our overall picture, we separate them out.

07:31 Let's take a look at what globin is.

07:33 These are chains of protein and their catabolized.

07:36 We break them down to be reused.

07:39 Look at the overall picture.

07:40 You see that the globin, and we've got it leading down to amino acids.

07:45 Good deal.

07:47 Now heme. Heme is separated into two things.

07:50 It's separated into iron and biliverdin.

07:53 Now biliverdin eventually becomes bilirubin.

07:57 The iron is recycled and it makes new red blood cells, sends it back to our bone marrow and the bilirubin attaches to the albumin and it's carried to the liver as unconjugated bilirubin.

08:09 Okay, go back and take a look at that picture that we had just talked about before.

08:15 Trace that all the way around.

08:17 So we've got bilirubin when we break down hemoglobin, right? The hemoglobin separates into heme and globin.

08:26 The globin turns into amino acids.

08:29 The heme goes back to liver.

08:31 It's attached to albumin as unconjugated, then it's conjugated and turned into bile.

08:38 So there are the first two steps: hemoglobin breaks into heme and globin.

08:43 Those are the concepts we wanted you to focus on in detail.

08:47 Now, this is where students kind of get tripped up.

08:50 Unconjugated, conjugated. It gets kind of confusing.

08:55 Unconjugated bilirubin is the one that you see first in our overall flow chart.

09:00 It's a waste product of hemoglobin breakdown and it's transported to the liver.

09:05 So what do you need to know about unconjugated bilirubin? It's the first part in the process.

09:11 So we're going to do something else to it.

09:13 We're going to conjugate it.

09:15 But it's a waste product of hemoglobin breakdown and it's transported back to the liver.

09:20 Now conjugated bilirubin is also known as a direct bilirubin.

09:25 Unconjugated bilirubin has been converted in the liver by an enzyme called UGT.

09:31 Now becomes water soluble.

09:33 So it's the same thing, but it's a water soluble version that can be excreted into bile and then cleared from the body.

09:41 Now, where does it go when you put it in bile? It ends up in your urine and your stool.

09:47 Okay. So let's look at the differences between unconjugated and conjugated.

09:52 Unconjugated, it's a waste product, not water-soluble.

09:57 Probably be a good idea for you to write that in and your notes - not water soluble.

10:01 If it's not water soluble, I can't get rid of it.

10:04 So it needs to be conjugated or changed.

10:07 You'll often see this referred to as direct bilirubin.

10:10 So once it's conjugated and make it a water-soluble version by connecting it up with an enzyme, then I can get rid of it.

10:17 It's going to go back to the bile and it's going to be cleared from the body in my urine and my stool.