Blood and Nerve Supply of the Kidneys
The main blood supply to the kidneys is through the renal artery & renal vein The kidneys receive 20-25% of the resting cardiac output. Renal blood flow through both kidneys is ~ 1200mL per minute. Renal a. segmental a. interlobar a. arcuate a. interlobular a. afferent arterioles glomerular capillaries efferent arterioles peritubular capillaries interlobular v. arcuate v. interlobar v. renal v. Many renal nerves originate in the renal ganglion and pass through the renal plexus into the kidneys along with renal arteries. Renal nerves are part of the sympathetic division of the ANS. Most are vasomotor nerves that regulate the flow of blood through the kidney by causing vasodilation or vasoconstriction of renal arteries.
The Nephron
Nephrons are the functional units of the kidneys. Each nephron consists of 2 parts: Renal Corpuscle , where blood plasma is filtered and the Renal Tubule , into which the filtered fluid passes.
The 2 components of the renal corpuscle are:
1. Glomerulus – network of blood capillaries
2. Glomerular (Bowman’s) Capsule – double walled epithelial cup
Blood plasma is filtered into the glomerular capsule from the glomerulus, and then the filtered fluid passes into the renal tubule .
The 3 components of the renal tubule are:
1. Proximal Convoluted Tubule
2. Loop of Henle
3. Distal Convoluted Tubule
The distal convoluted tubules of several nephrons empty into a single Collecting Duct. Collecting ducts then unite and converge into several hundred large Papillary Ducts which empty into the renal pelvis which leads to the ureters. In the nephron, the Loop of Henle connects the proximal and distal convoluted tubules. The first part of the loop is called the Descending Limb of the Loop of Henle. It then makes a hairpin turn and returns as the Ascending Limb of the Loop of Henle. Surrounding the renal tubule is the vasa recta . A complex network of blood vessels that continue to exchange substances with the tubular filtrate within the renal tubule.
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