Connecting tubule

Connecting tubule
Scheme of renal tubule and its vascular supply.
Latin	tubulus renalis arcuatus
Gray's	subject #253 1223
Precursor	Metanephric blastema

In the kidney, the collecting tubule (CNT, or junctional tubule, or arcuate renal tubule) is a tubular segment of the renal collecting duct system that connects the distal convoluted tubule to the cortical collecting duct.

Classification

Many sources include the connecting tubule as part of the collecting duct system. However, the embryological origin is more similar to the nephron than it is to the rest of the collecting duct (which derives from the ureteric bud), and other sources therefore classify the connecting tubule with the nephron.

Naming

Some connecting tubules, usually associated with juxtamedullary nephrons, arch upwards before reaching the cortical collecting ducts. It is this "arcuate" feature which gives the tubule its alternate name.

Function

It participates in the regulation of water and electrolytes, including sodium, and chloride.

The CNT is sensitive to both isoprotenerol (more so than the cortical collecting ducts) and antidiuretic hormone (less so than the cortical collecting ducts), the latter largely determining its function in water reabsorption.

References

• Eaton, Douglas C., Pooler, John P. (2004). Vander's Renal Physiology (6th ed.). Lange Medical Books/McGraw-Hill. ISBN 0-07-135728-9. 
• Imai M (1979). "The connecting tubule: a functional subdivision of the rabbit distal nephron segments". Kidney Int 15 (4): 346–56. doi:10.1038/ki.1979.46. PMID 513494. 

External links

• Physiology at MCG 7/7ch03/7ch03p18
• Types of tubules at ndif.org
• Diagram (#31) at benet.org