Blood Supply of the Kidneys: Study with Video Lessons, Practice Problems & Examples

The kidneys receive about one-fourth of the total cardiac output through the renal artery, filtering blood and removing waste. Blood enters the nephron via afferent arterioles, reaching the glomerulus, and exits through efferent arterioles. In cortical nephrons, efferent arterioles form peritubular capillaries for reabsorption, while in juxtamedullary nephrons, they create vasa recta, which help concentrate urine. Understanding this blood supply is crucial for grasping renal function and homeostasis.

Blood Supply to the Kidneys

In this video, we're going to be talking about blood supply to our kidneys. And this is an important topic because as you may remember, one of our kidneys' main jobs is to be filtering our blood and removing any waste products from that blood. So in order for the kidneys to do that, they're going to be receiving about one fourth of our total cardiac output. So they're receiving a pretty high volume of blood at any given time. And the blood supply will come into the kidneys from the renal artery, and then it will be exiting the kidneys via the renal vein. Alright. So looking at this image here, I know that this is a very busy image to look at. It looks a little bit like a mess, and I'll be honest, blood supply to the kidneys is functional, but it is not pretty. But that's okay. We are going to go through it one step at a time. And as we go through and talk about each anatomical feature, I'm going to be highlighting it in green so that you can see where you should be looking on this image. Before we do that, just to kind of orient you to what you're looking at more generally, what we have is a cortical nephron over here on the left. We have a collecting duct there in the middle, and then we have a juxtamedullary nephron over here on the right. You can imagine that everything from here up approximately is renal cortex, and then everything from here down would be renal medulla. Right? So we've got 2 nephrons with a cortical duct in between them. So that is what we are looking at there. Alright. So let's dive into our anatomy. So, within the renal cortex, our renal arteries are going to be branching into afferent arteriole. Okay. So you can see we have this renal artery right here and it's branching into this arteriole over here and then this one over here. And the one on the right is feeding a cortical nephron and the one on the left is feeding that juxtamedullary nephron. And if you remember our little trick from our neuro chapters, when we think afferent, we think arrive. Right? Those a's go together. So this is how blood is arriving at our renal corpuscle. Alright. So that is the blood supply coming into our nephron, okay, through the afferent arteriole. Alright. So blood is arriving and then those afferent arterioles feed the glomerular capillaries or that glomerulus, that big old ball of capillaries inside of our renal corpuscle. And you guys have seen that before. This part's pretty easy. So once our blood has gone through those glomerular capillaries, the glomerular capillaries are then going to be drained by the efferent arteriole. And you remember our little trick efferent exit. So this is how the blood is going to be leaving the glomerulus and leaving the renal corpuscle in order to form this very messy network of capillaries that we are about to look at. Now, one thing to note about the efferent arteriole is that the structures that it goes on to form are going to look a little bit different in our cortical nephrons versus in our juxtamedullary nephrons. And I'll explain what that means in just one second, but to kinda keep that in the back of your head. Alright. So we have our efferent arteriole blood is exiting our glomerulus, and that is going to feed our peritubular capillaries. So our peritubular capillaries are going to be forming a network around our renal tubule. You can see it's pretty much the entire cortical nephron is going to be covered in these peritubular capillaries weaving in and out of that renal tubule all over the place. And then the kind of top half of our juxtamedullary nephron is going to have those peritubular capillaries weaving in and out, really mostly on our proximal tubule and our distal tubule there. And the purpose of these peritubular capillaries is to be reabsorbing water and solutes from the tubule cell. And we're going to have many, many videos explaining how that works. If you don't understand that right now, don't worry about that. Just kinda keep in mind that that is their main alright. So you can see that these peritubular capillaries are pretty much covering the renal tubule in our cortical nephron, but there's quite a bit missing from our juxtamedullary nephron there. So, as I mentioned in our juxtamedullary nephrons, we're going to have another structure that we are working with, and those are our vasa recta. So in juxtamedullary nephrons, these efferent arterioles also go on to form the vasa recta. And these are basically a network of capillaries that are going to parallel those long nephron loops that dip deep into the renal medulla. And so even though these look very similar to the peritubular capillaries, they do have distinct anatomy. You can see how straight and how they really do run parallel to those nephron loops. Whereas in our peritubular capillaries, there's a lot of kind of weaving in between and coming in and out and movement in those. But these have these very straight features. And they also play a unique role in that they're going to help form concentrated urine. Do you guys remember that juxtamedullary nephrons kind of specialize in the creation of concentrated urine and these vasa recta help with that. And we will talk about that, in an upcoming video as well. Alright. So that is the major anatomy of the blood supply of our kidneys. Though, I know it's a lot going on here, but big, big takeaways are that the renal artery is the major blood supply of our kidney. The renal vein is where all that blood is exiting our kidney. We have our afferent arterioles that, where the blood is arriving coming into our nephron. We have our efferent arteriole where the blood is going to be exiting or leaving our nephron. And then our peritubular capillaries are going to be forming networks around our renal tubule helping with reabsorption. And specifically in our juxtamedullary nephrons, around that nephron loop we're going to have this very unique feature called our vasa recta. Alright. Great job with that one you guys, and I will see you all in our next video. Bye-bye.

Blood Supply of the Kidneys Example 1

Okay. So this one asks us, juxtamedullary nephrons play a role in forming concentrated urine. Based on that knowledge, which of the following structures must also play a role in forming concentrated urine? So we are looking for a structure that is unique to juxtamedullary nephrons. So based on that, our answer must be, C, vasa recta. Remember, afferent arterioles are just the arterioles that are entering our glomerular capsule. Our renal arteries are supplying the entire kidney with blood, and the glomerular capillaries are the capillaries inside of our glomerulus. So our answer here is C, vasa recta.

The arteriole that exits the glomerular capillaries and goes on to form the peritubular capillaries is the:

• A. Afferent arteriole.
• B. Efferent arteriole.
• C. Vasa recta.
• D. Renal vein.

Here’s what students ask on this topic:

What is the main blood supply to the kidneys?

The main blood supply to the kidneys comes from the renal artery. The renal artery branches off from the abdominal aorta and delivers about one-fourth of the total cardiac output to the kidneys. This high volume of blood is essential for the kidneys to perform their primary function of filtering blood and removing waste products. The blood exits the kidneys through the renal vein, which drains into the inferior vena cava.

How does blood enter and exit the nephron?

Blood enters the nephron through the afferent arteriole, which brings blood to the glomerulus, a network of capillaries within the renal corpuscle. After filtration in the glomerulus, blood exits the nephron via the efferent arteriole. The efferent arteriole then forms either peritubular capillaries in cortical nephrons or the vasa recta in juxtamedullary nephrons, facilitating further processes like reabsorption and concentration of urine.

What is the function of peritubular capillaries in the kidneys?

Peritubular capillaries form a network around the renal tubules in cortical nephrons. Their primary function is to reabsorb water and solutes from the renal tubule cells back into the bloodstream. This reabsorption process is crucial for maintaining fluid and electrolyte balance in the body. The peritubular capillaries weave in and out of the renal tubules, ensuring efficient reabsorption of essential substances.

What role do the vasa recta play in the kidneys?

The vasa recta are a network of capillaries that run parallel to the long nephron loops in juxtamedullary nephrons. They play a crucial role in concentrating urine by maintaining a gradient of solutes in the renal medulla. This gradient allows for the reabsorption of water from the filtrate, leading to the production of concentrated urine. The vasa recta's unique structure and function are essential for the kidneys' ability to conserve water and produce concentrated urine.

What is the difference between cortical and juxtamedullary nephrons in terms of blood supply?

Cortical nephrons and juxtamedullary nephrons differ in their blood supply structures. In cortical nephrons, the efferent arteriole forms peritubular capillaries that surround the renal tubules, facilitating reabsorption. In contrast, in juxtamedullary nephrons, the efferent arteriole forms the vasa recta, which run parallel to the nephron loops and help concentrate urine. These differences are crucial for the distinct functions of each nephron type in the kidney.