You are watching: The renal medulla is composed of _____, whereas the renal cortex is composed of _____.

The kidneys, depicted in number 22.4, space a pair the bean-shaped structures that are located simply below and posterior come the liver in the peritoneal cavity. The adrenal glands sit on peak of each kidney and also are additionally called the suprarenal glands. Kidney filter blood and purify it. All the blood in the human body is filtered numerous times a work by the kidneys; these organs usage up virtually 25 percent that the oxygen absorbed through the lungs to do this function. Oxygen enables the kidney cells to effectively manufacture chemical energy in the kind of ATP v aerobic respiration. The filtrate coming out of the kidney is referred to as urine.

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Figure 22.4. Kidneys filter the blood, creating urine the is save on computer in the bladder before elimination v the urethra. (credit: modification of work-related by NCI)
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Figure 22.5. The interior structure the the kidney is shown. (credit: change of occupational by NCI)
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Figure 22.6. The nephron is the sensible unit the the kidney. The glomerulus and also convoluted tubules are located in the kidney cortex, while collecting ducts are located in the pyramids that the medulla. (credit: modification of work-related by NIDDK)
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kidneys filter blood in a three-step process. First, the nephrons filter blood the runs with the capillary network in the glomerulus. Nearly all solutes, other than for proteins, space filtered out right into the glomerulus through a process called glomerular filtration. Second, the filtrate is gathered in the renal tubules. Most of the solutes acquire reabsorbed in the PCT by a process called tubular reabsorption. In the loop that Henle, the filtrate continues to exchange solutes and also water through the renal medulla and also the peritubular capillary network. Water is also reabsorbed during this step. Then, extr solutes and wastes are secreted right into the kidney tubules throughout tubular secretion, i m sorry is, in essence, the opposite process to tubular reabsorption. The collecting ducts collect filtrate comes from the nephrons and fuse in the medullary papillae. Native here, the papillae deliver the filtrate, now dubbed urine, into the boy calyces that eventually affix to the ureters through the renal pelvis. This entire procedure is portrayed in figure 22.7.

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Figure 22.7. Each part of the nephron performs a different function in filtering waste and also maintaining homeostatic balance. (1) The glomerulus forces little solutes the end of the blood by pressure. (2) The proximal convoluted tubule reabsorbs ions, water, and also nutrients indigenous the filtrate right into the interstitial fluid, and proactively transports toxins and also drugs indigenous the interstitial fluid into the filtrate. The proximal convoluted tubule likewise adjusts blood pH through selectively secreting ammonia (NH3) right into the filtrate, whereby it reacts with H+ to type NH4+. The an ext acidic the filtrate, the an ext ammonia is secreted. (3) The diminish loop that Henle is lined with cells include aquaporins that allow water to happen from the filtrate right into the interstitial fluid. (4) In the thin part of the ascending loop of Henle, Na+ and Cl- ion diffuse right into the interstitial fluid. In the thick part, these very same ions are actively transported right into the interstitial fluid. Since salt but not water is lost, the filtrate becomes much more dilute together it travels up the limb. (5) In the distal convoluted tubule, K+ and also H+ ions are selectively secreted into the filtrate, while Na+, Cl-, and also HCO3- ions are reabsorbed to maintain pH and electrolyte balance in the blood. (6) The collecting duct reabsorbs solutes and water indigenous the filtrate, developing dilute urine. (credit: alteration of work by NIDDK)