Vasa recta

From Wikipedia, the free encyclopedia

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	a_62/12156708

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") that descend from the cortex into the medulla.

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.

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

[edit] Histology

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

[edit] 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.

[edit] Nomenclature

According to Terminologia Anatomica^[3], 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.^[4]

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

• vasa recta (intestines) (in the ileum and jejunum)^[5]
• the straight portion of the seminiferous tubule^[6]

[edit] Pathology

The slow blood flow in vasa recta makes them a likely place of thrombosis in hypercoagulable states, or erythrocyte sickling in sickle cell disease. Ischemia that results may lead to renal papillary necrosis.

[edit] References

1. ^ Histology at BU 15802loa
2. ^ Physiology at MCG 7/7ch08/7ch08p07
3. ^ a_62/12156708 at Dorland's Medical Dictionary
4. ^ Histology at BU 15804loa
5. ^ Norman/Georgetown jejunumileum
6. ^ vasa+recta at eMedicine Dictionary

[edit] External links

• UIUC Histology Subject 937
• UMLS

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 → Cortical radial 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 → Duct of Bellini → 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 • Extraglomerular mesangial cell Filtration Glomerular basement membrane • Podocyte • Filtration slits • Intraglomerular mesangial cell • Tubular fluid Renal physiology Acid base physiology • Fluid balance