Nephrons are basic structural and functional units of the kidney. The number of nephrons a human kidney consists of ranges from 8 lakh to 1 crore. Nephrons can be distinguished into Cortical and Juxtamedullary on the basis of their location of the Malpighian corpuscles and the length of the loop of Henle.
Cortical vs Juxtamedullary Nephrons
The main difference between Cortical and Juxtamedullary nephrons is that cortical nephron’s Malpighian corpuscles are located in the outer cortex whereas Juxtamedullary nephron’s Malpighian corpuscles are located under the base of pyramids.
Also, in cortical nephrons the loop of Henle is short while in Juxtamedullary nephrons the loop of Henle is long. About 85% of the human kidney is made up of cortical nephrons and about 15% is made up of Juxtamedullary nephrons.
The main function of cortical nephrons is to carry out the major regulatory and excretory functions in the human body while the main function of the Juxtamedullary nephrons is to concentrate or dilute the urine.
Comparison Table Between Cortical and Juxtamedullary Nephrons
| Parameters of Comparison | Cortical Nephrons | Juxtamedullary Nephrons |
|---|---|---|
| Definition | Cortical nephrons are microscopic structural and functional units of the kidney with a short loop of Henle. | Juxtamedullary nephrons are microscopic structural and functional units of the kidney with a long loop of Henle. |
| Loop of Henle | They have a short loop of Henle and only penetrate the outer renal medulla. | They have a long loop of Henle and they extend deep into the renal medulla. |
| Malpighian Corpuscles | Their Malpighian corpuscles are located in the outer parts of the renal cortex. | Their Malpighian corpuscles are located close to the renal medulla. |
| Occurrence | Cortical nephrons are about 85% out of all the nephrons in the human kidney. | Juxtamedullary nephrons are about 15% out of all the nephrons in the human kidney. |
| Function | These nephrons carry out most and major part of the regulatory and excretory functions in the human body. | These nephrons concentrate or dilute the urine in the human body. |
What is Cortical Nephrons?
Cortical nephrons are microscopic structural and functional units of the kidney with a short loop of Henle that only penetrates the outer renal medulla. Their Malpighian corpuscles are located in the outer parts of the renal cortex.
Cortical nephrons occur in all vertebrates. They carry out the major part of the regulatory and excretory functions in the human body.
A small network of capillaries called glomerulus, is located at the beginning of every cortical nephron in the outer renal cortex. The glomerulus filters the blood coming from the afferent arteriole of the renal arterial circulation.
During the process of filtration, water, ions, amino acids, glucose and other small molecules are filtered. Red blood cells, white blood cells, large proteins and platelets remain inside the glomerulus.
The others flows to the renal calyx as urine. A vascular network situated around the loop of Henle called the Vasa recta reabsorbs most of the water, ions, amino acids and glucose.
What is Juxtamedullary Nephrons?
Juxtamedullary nephrons are microscopic structural and functional units of the kidney with a long loop of Henle that extends deep into the renal medulla. Their Malpighian corpuscles are located close to the renal medulla.
Juxtamedullary nephrons only occur in birds and mammals. They make up 15% of all nephron in the human kidney. A large glomerulus is situated at the very beginning of each of the Juxtamedullary nephron.
The filtration rate of these nephrons is directly proportional to the size of their glomerulus. The bigger the size of glomerulus, more is the rate of filtration. A large Vasa recta network surrounds the long loop of Henle in these nephrons.
The generation of hyperosmolar gradient leads to the production of concentrated urine. The main function of the Juxtamedullary nephrons is to concentrate or dilute urine in the body.
The concentration of urine depends on the quantity of water absorbed by the Vasa recta. If more water is absorbed, the urine will be more concentrated. If less water is absorbed, the urine will be more diluted.
Main Differences Between Cortical and Juxtamedullary Nephrons
- Cortical nephrons are microscopic structural and functional units of the kidney with a short loop of Henle whereas Juxtamedullary nephrons are microscopic structural and functional units of the kidney with a long loop of Henle.
- Cortical nephrons have a short loop of Henle and only penetrate the outer renal medulla whereas Juxtamedullary nephrons have a long loop of Henle and they extend deep into the renal medulla.
- Cortical nephron’s Malpighian corpuscles are located in the outer parts of the renal cortex while Juxtamedullary nephron’s Malpighian corpuscles are located close to the renal medulla.
- Cortical nephrons are about 85% out of all the nephrons whereas Juxtamedullary nephrons are about 15% out of all the nephrons in the human kidney.
- Cortical nephrons carry out most and major part of the regulatory and excretory functions while Juxtamedullary nephrons concentrate or dilute the urine in the human body.
- In Cortical nephron, the size of glomerulus and Vasa recta are small whereas in Juxtamedullary nephron, the size of glomerulus and Vasa recta are large.
Conclusion
Cortical nephrons are microscopic structural and functional units of the kidney with a short loop of Henle whereas Juxtamedullary nephrons are microscopic structural and functional units of the kidney with a long loop of Henle.
About 85% of the human kidney is made up of cortical nephrons and about 15% is made up of Juxtamedullary nephrons. The main function of cortical nephrons is to carry out the major regulatory and excretory functions while the main function of the Juxtamedullary nephrons is to concentrate or dilute the urine.
Cortical nephron’s Malpighian corpuscles are located in the outer parts of the renal cortex while Juxtamedullary nephron’s Malpighian corpuscles are located close to the renal medulla.
References
- https://journals.physiology.org/doi/abs/10.1152/ajprenal.1984.246.3.f349
- https://www.jci.org/articles/view/107663/files/pdf