The cortical and juxtamedullary nephron are two different types of kidneys. Both kidneys are essential for the body, but there are some differences between the two. For example, the cortical nephron is located in the cortex of the kidney, while the juxtamedullary nephron is located in the medulla of the kidney. Both are important for filtering blood, but some people have no idea what makes cortical and juxtamedullary nephron so different. So what are other differences between cortical and juxtamedullary nephron?

The article will focus on the cortical and juxtamedullary nephron, the difference between cortical and juxtamedullary nephron, and how they filter blood.

Summary Table:

Definitions:

What Is a Nephron?

A nephron is a part of the kidney that filters blood. Each kidney contains about one million nephrons. The word “nephron” comes from the Greek word for “kidney”. It is used in the same way as the word “nervous” in the phrase “nervous system”. It refers to all of the cells in a certain part of an organ. The cells that make up a nervous system are called neurons, and the cells that make up a kidney are called nephrons.

What Is a Cortical Nephron?

A cortical nephron is one of about 500,000 nephrons that lie along the inner surface of each kidney. Cortical means “relating to or affecting the outer layer or surface”. In other words, it means that it is located on the outer layer or surface of each kidney. Cortical nephrons account for about 80% of all the kidneys’ total filtration capacity and are more susceptible to damage from high blood pressure than juxtamedullary nephrons. Because they filter such large amounts of blood, cortical nephrons are also sometimes referred to as “major” nephrons.

What Is a Juxtamedullary Nephron?

A juxtamedullary nephron is one of about 20,000 nephrons that lie along the inner border of each kidney. Juxta means “next to” or “near”. In other words, it means that it is located near the middle of each kidney. Juxtamedullary nephrons account for about 20% of all the kidneys’ total filtration capacity and are less susceptible to damage from high blood pressure than cortical nephrons. Because they filter such small amounts of blood, juxtamedullary nephrons are also sometimes referred to as “minor” nephrons.

What Does a Nephron Do?

Each cortical nephron filters about 120 liters (30 gallons) of blood per day and produces about 1 liter (1 quart) of urine per day. Meanwhile, each juxtamedullary nephron filters about 15 liters (3 gallons) of blood per day and produces about 0.5 liters (1 pint) of urine per day. The filtered blood is then returned to the body through the renal vein. This occurs because the filtrate flows from the glomerulus through the Bowman’s capsule into the proximal convoluted tubule, then through the loop of Henle and into a distal convoluted tubule. From there, it passes into a collecting duct and on into a renal pelvis, then back into the body through the renal vein.

Cortical Vs. Juxtamedullary Nephron:

There are many differences between cortical and juxtamedullary nephron. Some of them are:

1. Filtering blood

Cortical nephron filters blood by having its structure called glomerulus. The glomerulus is made up of a network of capillaries and mesangial cells. The juxtamedullary nephron filters blood by using its tubules and loop of Henle.

2. Location

Cortical nephron is located in the cortex whereas juxtamedullary nephron is located in the medulla.

3. Blood supply

Cortical nephron is supplied by arteries from the renal artery and veins from the renal vein. Juxtamedullary nephron is supplied by the branches of the aorta and vena cava.

4. Urine formed

The urine formed by cortical nephron is called filtrate whereas the urine formed by juxtamedullary nephron is called tubular fluid. The function of tubular fluid is to form urine. This process is called ultrafiltration and it removes excess water from the blood. Tubular fluid can also carry out some biochemical reactions and hence, it is called the secretion.

5. Location of glomerulus

The glomerulus is located in the cortex whereas the juxtamedullary nephron does not have a glomerulus.

6. General function

The function of cortical nephron is to reabsorb the essential substances from the filtrate. It has the capacity to form urine of higher concentration than plasma. On the other hand, the function of juxtamedullary nephron is to eliminate excess water and solutes from the filtrate.

7. Amount of urine formed

The human body needs to reabsorb more water than what is lost through the urine. Hence, the amount of urine formed by cortical nephron is higher than that of juxtamedullary nephron. The reason behind this is that the cortical nephron has a large glomerulus. Usually, around 20% of blood is filtered by the glomerulus.

8. Metabolic functions

The function of cortical nephron is to maintain the body’s homeostasis whereas the function of juxtamedullary nephron is to regulate the volume and composition of blood.

9. Histology

The histology of cortical nephron is a well-developed glomerulus whereas the histology of juxtamedullary nephron is simple tubules.

10. Size

The size of cortical nephron is large whereas the size of juxtamedullary nephron is small. The size of a cortical nephron is about 1 mm whereas the size of a juxtamedullary nephron is about 0.5 mm.

11. Number of nephrons

The number of cortical nephrons is much more than that of juxtamedullary nephrons. The number of cortical nephrons is around 500,000 whereas the number of juxtamedullary nephrons is around 20,000.

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