The key difference between ascending and descending loop of Henle is that ascending loop of Henle is the thicker segment of the loop of Henle located just after the sharp bend of the loop while descending loop of Henle is the thinner segment located just before the sharp bend of the loop.
The nephron is the basic functional unit of our kidney that filter blood and produces urine in order to remove waste and extra fluid from the body. Nephron has two major parts: renal corpuscle and renal tubule. Renal corpuscle consists of glomerulus and Bowman’s capsule. Afferent arteriole enters the renal corpuscle with blood filled with waste and unnecessary chemicals. Glomerulus filters fluid and waste into the capsule, without letting blood cells and necessary molecules to leave the blood. Efferent arteriole leaves the glomerulus with filtered blood.
Renal tubule starts from the capsule and the first part of the renal tubule is proximal convoluted tubule. Then a special area called Henle loop runs and enters the second part of the renal tubule known as the distal convoluted tubule. Useful substances are reabsorbed into the blood from the renal tubule and the remaining fluid is excreted from the body as urine.
CONTENTS
1. Overview and Key Difference
2. What is Ascending Loop of Henle
3. What is Descending Loop of Henle
4. Similarities Between Ascending and Descending Loop of Henle
5. Side by Side Comparison – Ascending vs Descending Loop of Henle in Tabular Form
6. Summary
What is Ascending Loop of Henle?
Ascending loop of Henle is one of the two parts of the loop of Henle. It is located after the sharp bend of the loop, so it is the second part of the loop of Henle. It continues to the distal convoluted tubule and drains tubular fluid or urine to the distal convoluted tubule.
Figure 01: Nephron
There are two segments of the ascending loop of Henle. They are thin ascending limb and thick ascending limb. Thick ascending limb is thicker than the thin ascending limb. Thin ascending limb is the lower part of the ascending loop of Henle and it is lined by simple squamous epithelium. Thick ascending limb is the upper part and it is lined by simple cuboidal epithelium. It is the primary site for sodium reabsorption.
What is Descending Loop of Henle?
Descending loop of Henle is the first part of the loop of Henle. It is connected to the proximal convoluted tubule. Moreover, it is a part of the renal tubule. In comparison to the ascending loop of Henle, the descending loop of Henle is thinner.
Similar to the ascending loop of Henle, the descending loop of Henle also has two segments, which are thin and thick. But they are not distinguishable. The thin limb is lined by a simple squamous epithelium while the thick limb is lined by the simple cuboidal epithelium. The epithelium of the descending loop of Henle shows low permeability to ions. But it is highly permeable to water and moderately permeable to urea.
What are the Similarities Between Ascending and Descending Loop of Henle?
- Ascending and descending loop of Henle are two parts of the Henle loop of the nephron.
- The ascending loop of Henle is a direct continuation of the descending loop of Henle.
- They belong to the renal tubule.
- Both parts contain tubular fluid.
- Vasa recta run around both ascending and descending loop of Henle.
- Re-absorption takes place in both ascending and descending loop of Henle.
- Both ascending and descending loops of Henle form a U shaped hairpin-like structure.
What is the Difference Between Ascending and Descending Loop of Henle?
Ascending loop of Henle is the second segment of the loop of Henle and is located just after the sharp bend of the loop. Meanwhile, the descending loop of Henle is the first segment of the loop of Henle and is located just before the sharp bend of the loop. So, this is the key difference between ascending and descending loop of Henle. Precisely, the ascending loop of Henle is located between the descending loop of Henle and distal convoluted tubule, while the descending loop of Henle is located between proximal convoluted tubule and ascending loop of Henle.
Moreover, the ascending limb is much thicker than the descending limb. Thus, this is the structural difference between ascending and descending loop of Henle. The below tabulation shows more details of the difference between ascending and descending loop of Henle.
Summary – Ascending vs Descending Loop of Henle
The loop of Henle has two parts: the descending loop of Henle and the ascending loop of Henle. Descending loop of Henle is the first part located just before the sharp bend of the loop. Ascending loop of Henle is the second part located just after the sharp bend of the loop. The thickness of the ascending loop of Henle is higher than the thickness of the descending loop of Henle. So, this summarizes the difference between ascending and descending loop of Henle.
Reference:
1. “Ascending Limb of Loop of Henle.” Wikipedia. Wikimedia Foundation, July 26, 2019. Available here.
2.“Ion Absorption in The Loop of Henle – Function.” TeachMePhysiology. Accessed January 29, 2020. Available here.
Image Courtesy:
1. “Kidney Nephron” By Artwork by Holly Fischer – Urinary Tract Slide 20, 26 (CC BY 3.0) via Commons Wikimedia