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Difference Between Cortical and Juxtamedullary Nephron
The kidneys are complex organs that perform various vital functions in the body, including regulating blood pressure, electrolyte balance, acid-base balance, and filtering waste products from the blood. The functional unit of the kidney is the nephron, which consists of a renal corpuscle and a renal tubule.
There are two types of nephrons in the kidney: cortical nephrons and juxtamedullary nephrons. While both types of nephrons perform the same functions, there are some differences between them that are worth exploring.
What is Cortical Nephron?
Cortical nephrons are the most common type of nephron, comprising about 85% of all nephrons in the kidney. These nephrons are located in the renal cortex, which is the outer layer of the kidney. Cortical nephrons have a shorter loop of Henle that extends only a short distance into the renal medulla, and they are responsible for filtering blood and reabsorbing nutrients and water.
The glomerulus, which is a tuft of capillaries, is located in the renal cortex and is the site of blood filtration.
The proximal convoluted tubule, which is responsible for reabsorbing most of the filtered water and nutrients, is also located in the renal cortex.
The distal convoluted tubule, which plays a role in regulating electrolyte balance and acid-base balance, is located near the renal cortex-medulla junction.
At the beginning of each cortical nephron, in the outer renal cortex, is located a small network of capillaries called glomerulus. The main function of the glomerulus is to filter the blood, coming from an afferent arteriole of the renal arterial circulation.
During the filtration water, ions, amino acids, glucose, and other small molecules are filtered into the Bowman’s space of the nephrons. From there, the filtrate enters the renal tubule and follows a U-shaped path to the collecting ducts. Then it flows into the renal calyx as urine. Platelets, red and white blood cells, and large proteins remain inside the glomerulus. In the renal tubules of the cortical nephrons occurs reabsorption. Most of the water, ions, amino acids and glucose are reabsorbed through a vascular network situated around the loop of Henle, called vasa recta. As a result of the short loop of Henle, the vasa recta in the cortical nephrons is also small.
What is Juxtamedullary Nephron?
Juxtamedullary nephrons are located at the boundary between the renal cortex and medulla and are responsible for regulating water balance in the body. These nephrons have a longer loop of Henle that extends deep into the renal medulla, where it forms a hairpin bend called the loop of Henle's nephron.
The loop of Henle is divided into two limbs: the descending limb and the ascending limb. The descending limb is permeable to water and allows water to be reabsorbed from the tubular fluid into the interstitial fluid, whereas the ascending limb is impermeable to water and actively pumps out sodium and chloride ions, which contributes to the concentration gradient in the renal medulla.
The vasa recta, which is a network of capillaries, supplies the juxtamedullary nephrons with blood and plays a crucial role in maintaining the concentration gradient in the renal medulla.
Differences: Cortical Nephron and Juxtamedullary Nephron
The following table highlights the major differences between Cortical Nephron and Juxtamedullary Nephron −
Characteristics |
Cortical Nephron |
Juxtamedullary Nephron |
|---|---|---|
Definition |
Cortical nephron is a microscopic structural and functional unit of the kidney with a short loop of Henle. |
Juxtamedullary nephron is a microscopic structural and functional unit of the kidney with a long loop of Henle. |
Loop of Henle |
Cortical nephrons have a short loop of Henle, which penetrates only the outer renal medulla. |
Juxtamedullary nephrons have a long loop of Henle extending deep into the renal medulla. |
Malpighian corpuscles |
The Malpighian corpuscles of the cortical nephrons are located in the outer part of the renal cortex. |
The Malpighian corpuscles of the juxtamedullary nephrons are situated close to the renal medulla. |
Occurrence |
Cortical nephrons occur in all vertebrates. |
Juxtamedullary nephrons occur only in birds and mammals. |
Function |
The major part of the regulatory and excretory functions of the human body is carried out by the cortical nephrons. |
The juxtamedullary nephrons concentrate or dilute urine. |
Glomerulus |
At the beginning of each cortical nephron, in the outer renal cortex, is located a small glomerulus. |
At the beginning of each juxtamedullary nephron is located a large glomerulus. |
Vasa recta |
As a result of the short loop of Henle, the vasa recta of the cortical nephrons is also small. |
The long loop of Henle of the juxtamedullary nephrons is surrounded by a large vasa recta network. |
Conclusion
In summary, while both cortical and juxtamedullary nephrons perform similar functions, there are some differences in their structure and function.
Cortical nephrons are located in the renal cortex, have a shorter loop of Henle, and are responsible for filtering blood and reabsorbing nutrients and water. In contrast, juxtamedullary nephrons are located at the boundary between the renal cortex and medulla, have a longer loop of Henle, and are responsible for regulating water balance in the body.
Understanding the differences between these two types of nephrons is crucial for understanding kidney function and its role in maintaining homeostasis in the body.
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