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 is a key component in the kidney's ability to regulate fluid and electrolyte balance in the body, which is essential for maintaining homeostasis.

5 Must Know Facts For Your Next Test

1. The loop of Henle is divided into two main segments: the descending limb and the ascending limb.
2. The descending limb is permeable to water but impermeable to solutes, allowing water to be reabsorbed and creating a concentrated filtrate.
3. The ascending limb is impermeable to water but actively transports solutes, such as sodium, potassium, and chloride, out of the tubular fluid, further concentrating the urine.
4. The countercurrent multiplier system, involving the loop of Henle and the vasa recta, creates an osmotic gradient that drives the reabsorption and concentration of water in the kidney.
5. Loop diuretics, such as furosemide, work by inhibiting the active transport of solutes in the ascending limb of the loop of Henle, leading to increased urine output and decreased fluid retention.

Review Questions

• Explain the role of the loop of Henle in the kidney's ability to concentrate urine.
  • The loop of Henle is a crucial component of the kidney's countercurrent multiplier system, which creates an osmotic gradient that allows for the reabsorption and concentration of water. The descending limb of the loop is permeable to water, allowing it to be reabsorbed and creating a concentrated filtrate. The ascending limb is impermeable to water but actively transports solutes out of the tubular fluid, further concentrating the urine. This process, combined with the vasa recta, establishes the osmotic gradient necessary for the kidney to efficiently reabsorb water and maintain fluid and electrolyte homeostasis.
• Describe how loop diuretics, such as furosemide, work to increase urine output.
  • Loop diuretics, like furosemide, inhibit the active transport of solutes, such as sodium, potassium, and chloride, in the ascending limb of the loop of Henle. By blocking this active transport, the loop diuretics disrupt the kidney's ability to create the necessary osmotic gradient for water reabsorption. This leads to a decrease in water reabsorption and an increase in urine output, which can be beneficial for treating conditions like edema, hypertension, and heart failure by reducing fluid retention in the body.
• Analyze the relationship between the loop of Henle and the overall function of the renal system.
  • The loop of Henle is a critical component of the nephron and the kidney's ability to regulate fluid and electrolyte balance in the body. By creating an osmotic gradient through the countercurrent multiplier system, the loop of Henle allows for the reabsorption and concentration of water, which is essential for maintaining homeostasis. Disruptions to the loop of Henle, such as with loop diuretics, can have significant impacts on the renal system's overall function, leading to changes in urine output, fluid balance, and electrolyte levels. Understanding the loop of Henle's role in the renal system is crucial for comprehending the mechanisms behind diuretic medications and various kidney-related disorders.

Related terms

Nephron:

The functional unit of the kidney, consisting of the glomerulus, proximal convoluted tubule, loop of Henle, distal convoluted tubule, and collecting duct.

Countercurrent Multiplier System: The mechanism by which the loop of Henle, along with the vasa recta, creates a concentration gradient that allows for the reabsorption and concentration of water and solutes in the kidney.

Osmotic Gradient:

The difference in solute concentration between the tubular fluid and the surrounding interstitial fluid, which drives the reabsorption and concentration of water in the loop of Henle.