How well do you know the kidney?

The Structure and Function of the Kidney

• The kidney has three regions: the cortex, medulla, and renal pelvis.
• Each kidney contains around a million nephrons, which start in the cortex, loop down into the medulla, and back up to the cortex.
• The contents of the nephrons drain into the renal pelvis and the urine collects there before it flows into the ureter to be carried to the bladder for storage.
• The nephron is made up of a kidney tubule which has several sections: Bowman's capsule, proximal convoluted tubule, Loop of Henlé, distal convoluted tubule, and collecting duct.
• In the kidney, blood is filtered before the key substances are reabsorbed back into the blood again.
• The process occurs in the following order: ultrafiltration, selective reabsorption of glucose, and reabsorption of water and salts.
• Ultrafiltration occurs when arterioles branch off the renal artery and lead to each nephron, where they form a knot of capillaries (the glomerulus) sitting inside the cup-shaped Bowman’s capsule.
• As the filtrate drips through the Loop of Henle, necessary salts are reabsorbed back into the blood by diffusion.
• Water is also reabsorbed from the collecting duct in different amounts depending on how much water the body needs at that time.
• Glucose is the first substance to be reabsorbed at the proximal (first) convoluted tubule, and this takes place by active transport.
• Osmoregulation is the process of maintaining water and salt concentrations (osmotic balance) across membranes within the body.
• Maintaining water levels in the body is vital to prevent harmful changes occurring to cells of the body as a result of osmosis, and the water content of the body comes from two sources: water produced as a result of aerobic respiration and water in the diet.