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The vasa recta of the kidney, (vasa recta renis) are the straight arterioles, and the straight venules of the kidney, – a series of blood vessels in the blood supply of the kidney that enter the medulla as the straight arterioles, and leave the medulla to ascend to the cortex as the straight venules.
When renal blood flow is reduced (indicating hypotension) or there is a decrease in sodium or chloride ion concentration, the macula densa of the distal tubule releases prostaglandins (mainly PGI2 and PGE2) and nitric oxide, which cause the juxtaglomerular cells lining the afferent arterioles to release renin, activating the renin–angiotensin–aldosterone system, to increase blood pressure ...
The descending vasa recta, ascending vasa recta vessels, and the loop of Henle together form the countercurrent system of the kidney. In the afferent arteriole, blood is supplied at high pressure, which promotes filtration, and in the efferent arteriole, it is at low pressure, which promotes reabsorption .
Pressure in glomerular capillaries is therefore maintained and glomerular filtration rate remains adequate. However, in a state of very high angiotensin II for a prolonged period of time, the colloid oncotic pressure of the capillaries will increase, counteracting the increased hydrostatic pressure from the efferent constriction.
These structures include the vasa rectae (both spuria and vera), the venulae rectae, the medullary capillary plexus, the loop of Henle, and the collecting tubule. [1] The renal medulla is hypertonic to the filtrate in the nephron and aids in the reabsorption of water. Blood is filtered in the glomerulus by solute size.
Peritubular capillaries surround the cortical parts of the proximal and distal tubules, while the vasa recta go into the medulla to approach the loop of Henle. [1] [2] About one-fifth of the blood plasma is filtered into Bowman's capsule as the blood passes through the glomerular capillaries; four-fifths continues into the peritubular capillaries.
The renal circulation supplies the blood to the kidneys via the renal arteries, left and right, which branch directly from the abdominal aorta.Despite their relatively small size, the kidneys receive approximately 20% of the cardiac output.
The interlobular arteries pass directly outward between the medullary rays to reach the fibrous tunic, where they end in the capillary network of this part. These vessels do not anastomose with each other, but form end-arteries. In their outward course, they give off lateral branches, which are the afferent arterioles that supply the renal ...