The kidneys are bean-shaped organs, each about the size of our fist. The two kidneys are located at the center of the body, at the back, on either side of the spine. Each kidney is made up of small complex units called nephrons. Each kidney contains about 1 million nephrons.
The kidneys excrete metabolic waste products like urea, creatinine, hydrogen, potassium, and excess water through urine. The urine formation occurs continuously in the kidneys and is transported to the collection center called the urinary bladder via two drain pipelines called ureters.
At an opportune moment, the urine can be voided through the urethra, the terminal part of this effluent outlet. A sphincter prevents the involuntary passage of urine.
Figure: Cross-section of the Kidney
The internal morphology of the kidney in a cross-section is shown in the figure above. This structure plays a vital role in filtering blood and maintaining overall body fluid balance.
