Organs Kidney Cross Sectional (Right)

R Medulla

The renal medulla is the innermost part of the kidney. The renal medulla is split up into a number of sections, known as the renal pyramids. Blood enters into the kidney via the renal artery, which then splits up to form the interlobar arteries. The interlobar arteries each in turn branch into arcuate arteries, which in turn branch to form interlobular arteries, and these finally reach the glomeruli. At the glomerulus the blood reaches a highly disfavourable pressure gradient and a large exchange surface area, which forces the serum portion of the blood out of the vessel and into the renal tubules. The renal medulla contains the structures of the nephrons responsible for maintaining the salt and water balance of the blood.

R Cortex

The renal cortex is the outer portion of the kidney between the renal capsule and the renal medulla. In the adult, it forms a continuous smooth outer zone with a number of projections (cortical columns) that extend down between the pyramids. It contains the renal corpuscles and the renal tubules except for parts of the loop of Henle which descend into the renal medulla. It also contains blood vessels and cortical collecting ducts. The renal cortex is the part of the kidney where ultrafiltration occurs. Erythropoietin (a glycoprotein cytokine secreted by the kidney in response to cellular hypoxia, it stimulates red blood cell production (erythropoiesis) in the bone marrow) is produced in the renal cortex.

R Mayor Calyxes

The kidney consists of an outer cortex and an inner medulla. The cortex projects into the kidney dividing the medulla into triangular shaped renal pyramids, whose apices are surrounded by a minor calyx (calices = plural). The minor calices join to form a major calyx, which in turn unite to form the renal pelvis which exit the kidney to form the ureters. The calyx system of the kidney serves to drain urine. The smooth muscle walls of the calices are capable of peristalsis, which helps to propel urine through the kidneys, out through the renal pelvis and into the bladder via the ureters. The renal calyces are chambers of the kidney through which urine passes. The minor calyces surround the apex of the renal pyramids. Urine formed in the kidney passes through a renal papilla at the apex into the minor calyx, two or three minor calyces converge to form a major calyx, through which urine passes before continuing through the renal pelvis into the ureter. Source

R Renal Artery

Renal artery, one of the pair of large blood vessels that branch off from the abdominal aorta (the abdominal portion of the major artery leading from the heart) and enter into each kidney. (The kidneys are two bean-shaped organs that remove waste substances from the blood and aid in fluid conservation and in stabilization of the chemical composition of the blood.) At the inner concavity of each kidney there is an opening, known as the hilum, through which the renal artery passes. After passing through the hilum, the renal artery divides ordinarily into two large branches, and each branch divides into a number of smaller arteries, which bring blood to the nephrons, the functioning units of the kidney. Blood that has been processed by the nephrons ultimately reaches the renal vein, which carries it back to the inferior vena cava and to the right side of the heart. The renal arteries deliver to the kidneys of a normal person at rest 1.2 litres of blood per minute, a volume equivalent to approximately one-quarter of the heart’s output. Thus, a volume of blood equal to all that found in the body of an adult human being is processed by the kidneys once every four to five minutes. Although some physical conditions can inhibit blood flow, there are certain self-regulatory mechanisms inherent to the arteries of the kidney that allow some adaptation to stress. When the total body blood pressure rises or drops, sensory receptors of the nervous system located in the smooth muscle wall of the arteries are affected by the pressure changes, and, to compensate for the blood pressure variations, the arteries either expand or contract to keep a constant volume of blood flow. Source

R Renal Vein

There are two renal veins, a left and a right. They branch off the inferior vena cava and drain oxygen-depleted blood from the kidneys. As they enter the kidneys, each vein separates into two parts. The posterior veins assist in draining the back section of each kidney, while the anterior veins assist the front part. These veins also are responsible for draining blood from the ureter, which transports urine away from the kidneys to the urinary bladder. These veins should not be confused with the renal aorta. Unlike veins, the renal aorta delivers oxygenated blood to the kidneys. To simplify, the aorta carries blood to the kidneys while veins move the blood away. There are two notable diseases that involve the renal veins. If a clot (or thrombus) develops, this can cause renal vein thrombosis (RVT). Symptoms include a diminished flow of urine, along with blood in the urine. Treatment would require either anticoagulants and/or clot-removing surgery. Another issue is nutcracker syndrome (NCS), which occurs when one of the renal veins is compressed between the abdominal aorta and the superior mesenteric artery. Source

R Ureter

The ureter is a tube that carries urine from the kidney to the urinary bladder. There are two ureters, one attached to each kidney. The upper half of the ureter is located in the abdomen and the lower half is located in the pelvic area. The ureter is about 10 to 12 inches long in the average adult. The tube has thick walls composed of a fibrous, a muscular, and a mucus coat, which are able to contract. Source

R Minor Calyxes

R Interlobular Veins

These are veins in the cortex of the kidney that empty into the arcuate veins. The stellate veins join to form the interlobular veins, which pass inward between the rays receive branches from the plexuses around the convoluted tubules, and, having arrived at the bases of the renal pyramids, join with the venae rectae. Source

R Interlobular Arterie

These are renal blood vessels given off at right angles from the side of the arcuate arteries looking toward the cortical substance. 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 corpuscles. The afferent arterioles, then, enter Bowman’s capsule and end in the glomerulus.

R Renal Pelvis

The renal pelvis or pelvis of the kidney is the basin-like or funnel-like dilated proximal part of the ureter in the kidney. In humans, the renal pelvis is the point of convergence of two or three major calyces. Each renal papilla is surrounded by a branch of the renal pelvis called a calyx. The major function of the renal pelvis is to act as a funnel for urine flowing to the ureter.

R Arcuate Arteries

The arcuate arteries of the kidney are vessels of the renal circulation (which supplies the blood to the kidneys). They are located at the border of the renal cortex and renal medulla. At the junction between the renal cortex and renal medulla, the interlobar arteries form the arcuate arteries, which turn to follow the contours of the renal pyramids. From the arcuate arteries several branches, known as interlobular arteries, separate at right angles and extend through the renal cortex toward the exterior of the kidney. Source

R Arcuate Veins

Takes blood from the the inter lobular vein and sends it to the interlobar vein. The arcuate vein is a vessel of the renal circulation. It is located at the border of the renal cortex and renal medulla. Source