Kidney Structure

The kidneys are two bean shaped organs located under the diaphragm. They are responsible for osmoregulation, the balancing of water and solutes in blood.

Blood enters the kidneys through the renal artery at at the hilum, the concave side, and flows into smaller arterial branches and capillaries until it enters the nephrons.

Within the cortex the renal corpuscle which contains a glomerulus of capillaries surrounded by Bowman's capsule filters out nearly all solutes except for proteins. This filtrate is pooled in the renal tubules which contain different parts.

Nearest the corpuscle is the proximal convoluted tubule or PCT followed by the loop of henle with descending and ascending sides, and lastly the distal convoluted tubule or DCT.

In the tubules, some molecules like water, are reabsorbed back into surrounding capillaries where they rejoin into larger venioles and eventually form the renal vein which transports newly filtered blood back into circulation.

The remaining unabsorbed filtrate passes from the tubules into collecting ducts. Large numbers of these ducts join to form a medullary pyramid whose apex points towards the hilum. The apex empties the filtrate into a renal calyx that empties into the renal pelvis.

The renal pelvis opens up into the ureter and allows urine, the final filtrate, to pass from the kidney to the bladder.