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The website cannot function properly without these cookies, which is why they are not subject to your consent. These are cookies intended to measure the audience: it allows to generate usage statistics useful for the improvement of the website. Verify now. Toggle navigation. Institutional subscriptions support Language. Blood enters the kidneys through renal arteries. These arteries branch into tiny capillaries that interact with urinary structures inside the kidneys namely the nephrons.
Here the blood is filtered. Waste is removed and vital substances are reabsorbed back into the bloodstream. The filtered blood leaves through the renal veins. Each kidney consists of an outer renal cortex, an inner renal medulla, and a renal pelvis. Blood is filtered in the renal cortex. The renal medulla contains the renal pyramids, where urine formation takes place. Urine passes from the renal pyramids into the renal pelvis. This funnel-shaped structure occupies the central cavity of each kidney and then narrows as it extends out to join the ureter.
Urine drains from the renal pelvis into the ureter. Each kidney contains over 1 million tiny structures called nephrons. The nephrons are located partly in the cortex and partly inside the renal pyramids, where the nephron tubules make up most of the pyramid mass.
The kidney is bean-shaped with a superior and an inferior pole, anterior and posterior surfaces, and lateral and medial borders. The midportion of the kidney is often called the midpole. The kidney has a fibrous capsule, which is surrounded by perirenal fat. The kidney itself can be divided into renal parenchyma , consisting of renal cortex and medulla, and the renal sinus containing renal pelvis , calyces, renal vessels, nerves, lymphatics and perirenal fat. The renal parenchyma has two layers: cortex and medulla.
The renal cortex lies peripherally under the capsule while the renal medulla consists of renal pyramids , which are separated from each other by an inward extension of the renal cortex called renal columns. Urine is produced in the renal lobes , which consists of the renal pyramid with the associated overlying renal cortex and adjacent renal columns.
Each renal lobe drains at a papilla into a minor calyx , four or five of these unite to form a major calyx. Each kidney normally has two or three major calyces, which unite to form the renal pelvis. The renal hilum is the entry to the renal sinus and lies vertically at the anteromedial aspect of the kidney.
It contains the renal vessels and nerves, fat and the renal pelvis , which typically emerges posterior to the renal vessels, with the renal vein being anterior to the renal artery. See article: developmental anomalies of the kidney and ureter. Kidney length should not be less than three vertebral body lengths, and no more than four vertebral body lengths Antenatally, fetal kidneys show varying texture depending on gestational age.
It is echogenic in the first trimester, with decreasing echogenicity as the pregnancy progresses. Corticomedullary differentiation can be appreciated after 15 weeks of gestation but clear demarcation between cortex and medulla can be seen at 20 weeks.
Renal echogenicity decreases compared to liver and spleen after 17 weeks The collecting system arises from the ureteric bud , which arises from the mesonephric duct in the fourth week of gestation. The renal parenchyma arises from the metanephros, which appears in the fifth week, a derivative of the intermediate mesoderm.
The ureteric bud penetrates the metanephric mesoderm, which forms as a cup-shaped tissue cap. The ureteric bud dilates and subdivides to form twelve or so generations of tubules with the first generations fusing to form the renal pelvis, major and minor calyces, and renal pyramids with the later generations forming approximately a million renal tubules.
Under the regulation of complex signaling pathways, the ureteric bud incites the metanephric tissue to form small renal vesicles that eventually form primitive S-nephrons that are invaginated by endothelial cells from nearby angioblasts, then go on to form the definitive nephron.
The kidney develops in the pelvis but assumes its normal caudal abdominal location in adults due to disproportionate growth of the body in the lumbar and sacral regions Common diseases affecting the kidneys include:.
Anatomy: Abdominopelvic. Please Note: You can also scroll through stacks with your mouse wheel or the keyboard arrow keys. Updating… Please wait. Unable to process the form.
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