In the human urinary system there are two kidneys that are located between the dorsal body wall and parietal peritoneum on both the left and right sides.

Under microscopy, the urinary system is covered in a unique lining called urothelium, a type of transitional epithelium.

Urothelium covers most of the urinary system, including the renal pelvis, ureters, and bladder.

The main functions of the urinary system and its components are to: Average urine production in adult humans is about 1–2 litres (L) per day, depending on state of hydration, activity level, environmental factors, weight, and the individual's health.

Its chief function is to regulate the concentration of water and soluble substances like sodium by filtering the blood, reabsorbing what is needed and excreting the rest as urine.

It acts on the distal tubules and collecting ducts of the nephron and increases reabsorption of sodium from the glomerular filtrate.

[4] Vasopressin increases water permeability of the kidney's collecting duct and distal convoluted tubule by inducing translocation of aquaporin-CD water channels in the kidney nephron collecting duct plasma membrane.

Urine is ejected through the urethra from the penis or vulva in placental mammals and through the cloaca in other vertebrates.

[6] Diabetes also can have a direct effect in urination due to peripheral neuropathies, which occur in some individuals with poorly controlled blood sugar levels.

[7] Urinary incontinence can result from a weakening of the pelvic floor muscles caused by factors such as pregnancy, childbirth, aging, and being overweight.

Findings recent systematic reviews demonstrate that behavioral therapy generally results in improved urinary incontinence outcomes, especially for stress and urge UI, than medications alone.

[10] The urinary tract including the ureters, as well as their function to drain urine from the kidneys, has been described by Galen in the second century AD.

[10] This was improved on by VF Marshall who is the first published use of a flexible endoscope based on fiber optics, which occurred in 1964.

[10] The insertion of a drainage tube into the renal pelvis, bypassing the ureters and urinary tract, called nephrostomy, was first described in 1941.