The human body has a pair of kidneys – bean-shaped organs that are integral in filtering harmful wastes from the blood and expelling them as urine. They are the main organ of the excretory system, which also includes the ureters, urinary bladder, and urethra. The kidneys are situated just underneath the ribs on either side of the spinal column.
Nephrons – long, coiling tubular structures – are the functional units of the kidney. They are the structures through which blood enters and gets rid of its waste products, such as salts, toxins, and excess water. In healthy adult humans, each of our kidneys can have just over one million nephrons.
Kidneys can be divided into three main sections – the cortex, renal medulla and renal pelvis. Solutes from the blood are removed at the cortex. These substances are collected alongside excess fluid to form urine at the renal pyramids of the medulla. Urine then flows into the renal pelvis, which funnels the liquid into a tube called the ureter which empties into the urinary bladder.
This kidney diagram with labels can be an informative visual aid, illustrating the structure and function of the kidney and its role in preserving homeostasis by excreting waste substances from the blood.