Hi, in the last video we had a macroscopic look at the anatomy of the kidney. In this video we are going to take a microscopic look at the kidney and check out the structure of the nephron. This video does not cover the function of the nephron and the concentration of urine, as this is covered in the nephron function handwritten tutorial.
So I'll start by drawing a nephron. Part of the nephron sits within the cortex of the kidney and part within the medulla. The parts in the cortex are the glomerulus, the proximal tubule, and the distal tubule, whereas the loop of Henle dips down into the medulla and then back up into the cortex. You may hear of two varieties of nephron, cortical nephrons and juxtamedullary nephrons.
The structure is very similar. with the main difference being how superficially the glomerulus sits in the cortex and how deep the loop of Henle dips into the medulla. Cortical nephrons are superficial and juxtamedullary nephrons are deeper.
In fact they lie next to the medulla which is the meaning of juxtamedullary. So let's start at the beginning. Here we have the glomerulus. which is where the blood is filtered. And you can see a ball of capillaries inside the glomerulus.
I'm not going to talk much about the glomerulus because it is covered in detail in the next video in the series. And here are two very important arterioles. The afferent arteriole, which brings blood to the glomerulus for filtration, and the efferent arteriole, which takes the filtered blood away from the glomerulus i always remember which is which by thinking that a comes before e and therefore the afferent is before the efferent now the filtrate which will eventually become urine needs things taken out of it and also needs things put into it.
To do this, it travels along this series of tubes. The first part is the proximal convoluted tubule, which is often referred to as just the proximal tubule. This big loop here is called the loop of Henle.
This is the part that dips into the medulla. Now there are four limbs of the loop of Henle. They are the thick descending limb, the thin descending limb, the thin ascending limb, and the thick ascending limb.
Note that the tube then passes by the glomerulus and the arterioles. It is at this point that the Juxtaglomerular apparatus lies. We will talk more about the Juxtaglomerular apparatus in the next tutorial. This is a distal convoluted tubule at this point, and I've labelled this here.
Then the distal tubule connects to the collecting duct. I spoke about the collecting duct in the last tutorial, and said that it takes the urine to the renal papilla, in order for it to flow onward and out of the kidney. Now the last thing to talk about is the vasculature of the nephron, and this is really important.
The efferent arteriole of the kidney carries blood away from the glomerulus, and then it supplies two capillary beds. The first is the peritubular capillaries, which supply blood to the... proximal and distal tubules.
The other is the vasorecti, which supply blood to the loop of Henle. These two sets of capillaries will provide water and solutes to be secreted into the filtrate and blood to carry away water and solutes. and solutes reabsorbed from the kidney.
In the next tutorial, we will take a closer look at the glomerulus, and explore the cell types that make up the glomerulus, and talk about their function. For more free tutorials, and the PDF for this tutorial, visit www.handwrittentutorials.com.