Loop of Henle

Definition

The loop of Henle is a U-shaped structure within the nephron of the kidney that plays a crucial role in the reabsorption and concentration of urine. It connects the proximal convoluted tubule to the distal convoluted tubule, and its unique structure and function are integral to the kidney's ability to maintain fluid and electrolyte balance in the body.

5 Must Know Facts For Your Next Test

1. The loop of Henle is composed of a descending limb and an ascending limb, which have distinct structural and functional characteristics.
2. The descending limb of the loop of Henle is permeable to water, allowing for the reabsorption of water and the concentration of the filtrate.
3. The ascending limb of the loop of Henle is impermeable to water but selectively permeable to certain solutes, such as sodium and chloride, which are actively transported out of the tubule.
4. The unique countercurrent multiplier system created by the loop of Henle is essential for the kidney's ability to concentrate urine and maintain fluid and electrolyte balance.
5. Disruptions to the structure or function of the loop of Henle can lead to various kidney disorders, such as renal tubular acidosis and diabetes insipidus.

Review Questions

• Describe the structure and location of the loop of Henle within the nephron.
  • The loop of Henle is a U-shaped structure within the nephron, connecting the proximal convoluted tubule to the distal convoluted tubule. It is composed of a descending limb and an ascending limb, which have distinct structural and functional characteristics. The loop of Henle is located in the medulla of the kidney, with the descending limb extending into the inner medulla and the ascending limb returning to the cortex.
• Explain the role of the loop of Henle in the process of urine concentration.
  • The loop of Henle is a crucial component of the kidney's countercurrent multiplier system, which is responsible for the concentration of urine. The descending limb of the loop is permeable to water, allowing for the reabsorption of water and the concentration of the filtrate. The ascending limb, in contrast, is impermeable to water but selectively permeable to certain solutes, such as sodium and chloride, which are actively transported out of the tubule. This creates an osmotic gradient that drives the reabsorption of water and the concentration of urine as it passes through the loop of Henle.
• Analyze how the structure and function of the loop of Henle contribute to the kidney's overall role in fluid and electrolyte balance.
  • The loop of Henle's unique structure and function are integral to the kidney's ability to maintain fluid and electrolyte balance in the body. The countercurrent multiplier system created by the loop of Henle allows the kidney to concentrate urine, which is essential for conserving water and regulating fluid volume. The selective permeability of the ascending limb to certain solutes, such as sodium and chloride, also allows the kidney to reabsorb and retain these important electrolytes, while excreting excess amounts. By precisely controlling the reabsorption and excretion of water and electrolytes, the loop of Henle plays a crucial role in the kidney's overall function of maintaining homeostasis and regulating the body's fluid and electrolyte balance.

Related terms

Nephron:

The functional unit of the kidney, consisting of a renal corpuscle and a renal tubule, responsible for the filtration, reabsorption, and secretion of urine.

Proximal Convoluted Tubule: The first section of the renal tubule, where the majority of water and solute reabsorption occurs.

Distal Convoluted Tubule:

The final section of the renal tubule, where the final adjustments to urine composition are made before it is collected in the collecting duct.