Loop of Henle

Definition

The loop of Henle is a U-shaped part of the nephron in the kidney that plays a crucial role in concentrating urine and conserving water. It consists of a descending limb and an ascending limb, each with distinct functions in reabsorbing water and ions.

5 Must Know Facts For Your Next Test

1. The descending limb of the loop of Henle is permeable to water but not to solutes.
2. The ascending limb is impermeable to water but actively transports sodium, potassium, and chloride ions out into the surrounding medulla.
3. Countercurrent multiplication in the loop of Henle helps establish a concentration gradient in the medulla, which aids in water reabsorption from the collecting ducts.
4. Diuretics like furosemide act on the ascending limb of the loop of Henle to inhibit sodium and chloride reabsorption, leading to increased urine output.
5. The length of the loop of Henle can vary among species and is correlated with their ability to concentrate urine; desert animals often have longer loops.

Review Questions

• What are the primary functions of the descending and ascending limbs of the loop of Henle?
• How does countercurrent multiplication work in establishing a concentration gradient in the kidney?
• Which class of diuretics targets the loop of Henle, and what effect do they have on urine production?

Related terms

Nephron: The basic structural and functional unit of the kidney responsible for filtering blood and producing urine.

Countercurrent Multiplication: A mechanism involving fluid flow in opposite directions through adjacent segments of a nephron loop that multiplies osmotic gradients.

Diuretics: Medications that increase urine production by inhibiting ion reabsorption at various sites within nephrons.