Vasa recta: Definition from Answers.com

Artery: Vasa recta

A nephron, the vasa recta is labelled arteria recta
Latin	arteriolae rectae renis
Gray's	subject #253 1224
Source	Arcuate arteries of the kidney, efferent arteriole
Branches	Straight venules of kidney, arcuate vein
Dorlands / Elsevier	Vasa recta renis

For the intestinal structure, see Vasa recta (intestines)

In the blood supply of the kidney, the vasa recta renis (or straight arteries of kidney, or straight arterioles of kidney) form a series of straight capillaries (recta is from the Latin for "straight") in the medulla.They lie parallel to the loop of Henle.

These vessels branch off the efferent arterioles of juxtamedullary nephrons (those nephrons closest to the medulla), enter the medulla, and surround the loop of Henle.

1 Histology
2 Function
3 Nomenclature
4 Pathology
5 References
6 External links

Histology

On a slide, vasa recta can be distinguished from the tubules of the loop of Henle by the presence of blood.^[1]

Function

Each of the vasa recta has a hairpin turn in the medulla and carries blood at a very slow rate, two factors crucial in the maintenance of countercurrent exchange that prevent washout of the concentration gradients established in the renal medulla.^[2]

The maintenance of this concentration gradient is one of the components responsible for the kidney's ability to produce concentrated urine.

On the descending portion of the vasa recta, NaCl and urea are reabsorbed into the blood, while water is secreted. On the ascending portion of the vasa recta, NaCl and urea are secreted into the interstitium, while water is reabsorbed.

Nomenclature

According to Terminologia Anatomica , the term "vasa recta renis" is an alternate name for "arteriolae rectae renis", and a separate term, venulae rectae renis, is used to identify the venous portion.

However, other sources consider "vasa recta renis" to refer to both the arterial and venous portions.^[3]

The "renis" is often omitted, but there do exist two other structures with the same name:

vasa recta (intestines) (in the ileum and jejunum)^[4]
the straight portion of the seminiferous tubule^[5]

Pathology

The slow blood flow in vasa recta makes them a likely location of thrombosis in hypercoagulable states, or tissue loss^[6] due to erythrocyte sickling in sickle cell disease. Ischemia that results may lead to renal papillary necrosis.

References

^ Histology at BU 15802loa
^ Physiology at MCG 7/7ch08/7ch08p07
^ Histology at BU 15804loa
^ jejunumileum at The Anatomy Lesson by Wesley Norman (Georgetown University)
^ vasa+recta at eMedicine Dictionary
^ ter Maaten JC, Serné EH, van Eps WS, ter Wee PM, Donker AJ, Gans RO (March 2000). "Effects of insulin and atrial natriuretic peptide on renal tubular sodium handling in sickle cell disease". Am. J. Physiol. Renal Physiol. 278 (3): F499–505. PMID 10710555. http://ajprenal.physiology.org/cgi/pmidlookup?view=long&pmid=10710555.

External links

v • d • e Urinary system – Kidney

Layers	Renal fascia • Renal capsule • Renal cortex (Renal column) • Renal medulla (Renal sinus, Renal pyramids, medullary interstitium) • Renal lobe • Cortical lobule • Medullary ray • Nephron

Afferent circulation	Renal artery → Segmental arteries → Interlobar arteries → Arcuate arteries → Interlobular arteries → Afferent arterioles → Renal corpuscle (Glomerulus, Bowman's capsule)

Renal tubule	Proximal tubule → Loop of Henle (Descending, Thin ascending, Thick ascending) → Distal convoluted tubule → Connecting tubule → Collecting ducts aka Duct of Belini → Renal papilla → Minor calyx → Major calyx → Renal pelvis → Ureter

Efferent circulation	Glomerulus → Efferent arterioles → Peritubular capillaries / Vasa recta → Arcuate vein → Interlobar veins → Renal vein

Juxtaglomerular apparatus	Macula densa • Juxtaglomerular cells • Mesangium/Extraglomerular mesangial cell

Filtration	Glomerular basement membrane • Podocyte • Filtration slits • Mesangium/Intraglomerular mesangial cell • Tubular fluid

Renal physiology	Acid base physiology • Fluid balance

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	What is the vasa recta? (anatomy)
	Vasa recta (intestines)
	Renal circulation

	The name of the blood vessels that are found in the medulla as part of the vasa recta are the? Read answer...
	The net action of the vasa recta is to remove water from and dilute solutes in the interstitial fluid of the renal medulla? Read answer...
	What describes the process in which molecules are selectively removed from the tubule moved into interstitial space and removed from the kidneys by the peritubular capillaries and the vasa recta? Read answer...

	Is the vasa recta a part of the bowman's capsule?
	Counter current mechanics in vasa recta?
	What arteries are also known as vasa recta?

		Medical Dictionary. The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Read more
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