Organ
Collecting duct system
The final regulated route through cortex and medulla
High-yield
Vasopressin promotes apical aquaporin-2 insertion in water-responsive cells. Urine concentration also requires an appropriate medullary osmotic gradient.
Overview
Collecting ducts receive connecting-tubule fluid and merge while descending toward a renal papilla. Their cells make final adjustments to water, electrolyte and acid-base excretion. Papillary ducts open into a minor calyx through the papillary surface.
Reference facts
- Location
- Extends from cortical medullary rays through the medulla to the papillary tip.
- Parts
- Cortical, outer medullary and inner medullary segments unite into papillary ducts. Principal and intercalated cells are prominent proximally; epithelial composition changes toward the inner medulla.
- Blood supply
- Supported by cortical peritubular capillaries and medullary vasa recta.
- Innervation
- Renal sympathetic activity influences tubular function, while vasopressin and aldosterone provide major hormonal regulation.
- Function
- Adjusts water reabsorption, sodium retention and potassium handling; intercalated-cell transport contributes to acid-base balance, while inner medullary urea transport supports concentration.
Clinical correlation
Vasopressin deficiency or renal resistance can cause excessive dilute urine; lithium can cause acquired resistance. Impaired distal acid secretion may cause type 1 renal tubular acidosis, with urine insufficiently acidified for the systemic acidosis and increased calcium-phosphate stone risk.
Frequently asked questions
Where is the collecting duct system located?
The collecting duct system lies extends from cortical medullary rays through the medulla to the papillary tip.
What does the collecting duct system do?
Adjusts water reabsorption, sodium retention and potassium handling; intercalated-cell transport contributes to acid-base balance, while inner medullary urea transport supports concentration.
What are the parts of the collecting duct system?
Cortical, outer medullary and inner medullary segments unite into papillary ducts. Principal and intercalated cells are prominent proximally; epithelial composition changes toward the inner medulla.
What is the blood supply of the collecting duct system?
The collecting duct system is supplied by the supported by cortical peritubular capillaries and medullary vasa recta.