Main Difference – Cortical Nephron vs Juxtamedullary Nephron
Cortical and juxtamedullary nephrons are the two types of nephrons found in the kidney of vertebrates. Both types of nephrons consist of a glomerulus, Bowman’s capsule, proximal convoluted tubule, loop of Henle, distal convoluted tubule, and a collecting duct. The main difference between cortical nephron and juxtamedullary nephron is that cortical nephron contains a short loop of Henle which only extends into the outer region of the renal medulla whereas juxtamedullary nephron contains a longer loop of Henle which extends deeper into the inner medulla. Juxtamedullary nephrons have a vital role in concentrating urea.
Key Areas Covered
1. What is a Cortical Nephron
– Definition, Structure, Role
2. What is a Juxtamedullary Nephron
– Definition, Structure, Role
3. What are the Similarities Between Cortical and Juxtamedullary Nephron
– Outline of Common Features
4. What is the Difference Between Cortical and Juxtamedullary Nephron
– Comparison of Key Differences
Key Terms: Cortical Nephron, Filtration, Glomerulus, Juxtamedullary Nephron, Loop of Henle, Reabsorption, Vasa Recta
What is a Cortical Nephron
Cortical nephron refers to nephrons that contain small, short loop of Henle, penetrating only the outer renal medulla. Most nephrons (85% of the total nephron) in the human kidney are cortical nephrons. Therefore, the excretory and regulatory functions of the body are mainly carried out by cortical nephrons. They consist of a small glomerulus located in the outer renal cortex. The glomerulus receives blood through the afferent arteriole whereas the blood leaves through the efferent arteriole. Filtration of blood is the main function of the glomerulus. During the filtration, water, glucose, amino acids, ions, and other small molecules up to 40 kDa are filtered into the Bowman’s space, which is continuous with the proximal convoluted tubule of the nephron. Red blood cells, white blood cells, platelets and large proteins such as fibrinogens remain inside the glomerulus capillaries. The reabsorption of a cortical nephron is shown in figure 1.
Figure 1: Reabsorption
The reabsorption occurs in the renal tubules of the cortical nephrons. Most of the water, glucose, amino acids, and ions are reabsorbed in the renal tubules. The reabsorption of important molecules occurs through the vasa recta, which is a vascular network around the loop of Henle. Since the loop of Henle is short, the vasa recta is also small in the cortical nephrons. The final filtrate of a nephron is called the urine.
What is a Juxtamedullary Nephron
Juxtamedullary nephron refers to nephrons whose loop of Henle extend deep into the renal medulla. Only 15% of the nephrons in the human kidney are juxtamedullary nephrons. The renal corpuscle of the juxtamedullary nephrons is found in the renal medulla. These nephrons contain a large glomerulus, increasing the glomerular filtration rate of the nephron. Since loop of Henle of the juxtamedullary nephrons is long, it extends deep into the renal medulla. The structure of the cortical and juxtamedullary nephrons are shown in figure 2.
Figure 2: Cortical nephron (right) and juxtamedullary nephron (left)
The main function of the juxtamedullary nephron is to concentrate or dilute urine. The absorption of more water by the vasa recta may produce more concentrated urine while the less reabsorption of water may produce diluted urine. Animals such as birds that live in terrestrial environments have more juxtamedullary nephrons than cortical nephrons.
Similarities Between Cortical Nephron and Juxtamedullary Nephron
- Cortical nephron and juxtamedullary nephron are two types of nephrons in the kidney.
- Both cortical nephron and juxtamedullary nephron consist of a glomerulus, Bowman’s capsule, proximal convoluted tubule, loop of Henle, distal convoluted tubule, and a collecting duct.
- Glomerulus, Bowman’s capsule, and proximal and distal convoluted tubules of both cortical and juxtamedullary nephrons occur in the renal cortex.
- The loop of Henle and collecting duct of both cortical and juxtamedullary nephrons extend to the renal medulla.
- Both cortical nephron and juxtamedullary nephron filter blood to produce urine.
Difference Between Cortical Nephron and Juxtamedullary Nephron
Definition
Cortical Nephron: Cortical nephron is a nephron having a small, short loop of Henle, which penetrates only the outer renal medulla.
Juxtamedullary Nephron: Juxtamedullary nephron is a nephronswhose loop of Henle extends deep into the renal medulla.
Loop of Henle
Cortical Nephron: Cortical nephrons contain a short loop of Henle.
Juxtamedullary Nephron: Juxtamedullary nephron contains a long loop of Henle.
Length of Loop of Henle
Cortical Nephron: The loop of Henle of the cortical nephron only extends to the outer renal medulla.
Juxtamedullary Nephron: The loop of Henle of the juxtamedullary nephron extends to the deeper renal medulla.
Vasa recta
Cortical Nephron: Cortical nephron contains a reduced vasa recta.
Juxtamedullary Nephron: Juxtamedullary nephron contains a large network of vasa recta.
Glomeruli
Cortical Nephron: The glomeruli of the cortical nephron is located in the outer renal cortex.
Juxtamedullary Nephron: The glomeruli of the juxtamedullary nephron is located near the corticomedullary border.
Size of the Glomeruli
Cortical Nephron: Cortical nephrons contain small glomeruli.
Juxtamedullary Nephron: Juxtamedullary nephrons contain large glomeruli.
Glomerular Filtration Rate
Cortical Nephron: Cortical nephron consists of a low glomerular filtration rate.
Juxtamedullary Nephron: Juxtamedullary nephron consists of a high glomerular filtration rate due to the presence of a large glomerulus.
Abundance
Cortical Nephron: The 85% of the nephrons in a kidney are cortical nephrons.
Juxtamedullary Nephron: Only 15% of the nephrons of the kidney are juxtamedullary nephrons.
Importance
Cortical Nephron: Cortical nephrons perform excretory and regulatory functions of a kidney.
Juxtamedullary Nephron: Juxtamedullary nephron is involved in concentrating or diluting urea.
Conclusion
Cortical nephron and juxtamedullar nephron are the two types of nephrons in the kidney. The loop of Henle of the cortical nephron extends only to the outer renal medulla while that of the juxtamedullary nephron extends to the deeper of the renal medulla. Cortical nephrons are mainly involved in the excretory and regulatory functions of the body while juxtamedullary nephrons concentrate or dilute urine. Thus, the main difference between cortical nephron and juxtamedullary nephron is their structure and function.
Reference:
1.“ Types Of Nephrons.” Tutorvista.Com, Available here.
Image Courtesy:
1. “2618 Nephron Secretion Reabsorption” By OpenStax College – Anatomy & Physiology, Connexions Web site. Jun 19, 2013 (CC BY 3.0) via Commons Wikimedia
2. “Kidney Nephron” By Artwork by Holly Fischer – Urinary Tract Slide 20, 26 (CC BY 3.0) via Commons Wikimedia
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