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What Is the Kidney's Collecting Duct?

The collecting duct is part of the filtration system in the nephrons of the kidneys.
Fluid from the kidney eventually drains into the ureter.
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  • Written By: Mary McMahon
  • Edited By: Kristen Osborne
  • Last Modified Date: 20 October 2014
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The collecting ducts are a series of small tubes inside the kidneys that funnel urine into the renal pelvis for drainage into the ureter. Once in the ureter, the urine can be pushed into the bladder for elimination. The structure of the kidneys is quite complex and includes a large number of these tubes in an interconnected drainage system. People with urinary tract disorders can potentially develop problems along part of the collecting ducts, and a kidney collecting duct issue can cause symptoms like difficulty urinating and edema.

Filtration in the kidneys happens as fluids and salts in the body are pushed through structures called nephrons. Depending on the balance of fluids and electrolytes in the body, the nephrons can retain varying amounts of material. Excess is delivered into the renal tubules and collected for emptying into cortical collecting ducts. Each cortical collecting duct joints with other ducts to make a medullary connecting duct, which eventually drains into a papillary duct, emptying urine into the renal pelvis for expression through the ureter.

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The body can control the level of dilation and absorption in each collecting duct. If salts need to be retained to maintain an electrolyte balance, natural adjustments happen inside the nephrons and collecting ducts. Hormones can tense the muscle to make the ducts smaller, or relax the muscles to allow more fluid to escape. The collecting duct is part of a larger system designed to maintain a metabolic balance, supplying the needs of the body and eliminating wastes.

Disorders involving the kidneys can include a collecting duct occlusion, where blockages develop and fluids cannot drain, along with cancers arising in the cells that line these ducts. The cancer can invade the cell wall and spread to the rest of the kidney, developing into a potentially large tumor that will interfere with kidney function. Kidney function tests can reveal the presence of abnormal growths or electrolyte imbalances indicative of a problem in the kidneys.

The collecting duct network is extensive, supplying drainage to all the nephrons in the kidney and making the kidneys extremely efficient. High volumes of fluid are processed by the kidneys every day as they work to clean body fluids, eliminate unwanted and unneeded chemical compounds, and to maintain the balance of fluids and electrolytes in a variety of conditions, ranging from keeping fluid levels optimal for an athlete in the heat to expressing salts when people eat high salt diets.

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wavy58
Post 2

My grandmother had problems in her kidney collecting duct, and she developed edema due to all the fluid retention. She experienced swelling in her arms, hands, ankles, feet, and legs at different times.

At first, she woke up with puffy bags around her eyes. Then, she started to notice she putting on weight. She had always been kind of pudgy, so she did not think much about it until she noticed a marked increase in the size of her hands, feet, and ankles. She went to her doctor, who diagnosed her with nephrotic syndrome.

shell4life
Post 1

I have a kidney disease involving growth of millions of cysts. The cysts cause high blood pressure, and I know that high sodium intake can increase blood pressure as well.

My doctor recommended that I lower my sodium intake. I did not know until reading this that the kidneys actually are responsible for expressing salts. His recommendation makes sense to me now.

I started putting less salt on my food and buying the low sodium version of foods when available. My blood pressure has actually decreased since I've starting eating better, and I guess I have helped my kidneys.

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