Virtsajohtimet

Virtsajohtimet, also known as ureters, are two narrow tubes that transport urine from the kidneys to the bladder. Each ureter is about 25 to 30 centimeters long and approximately 5 millimeters in diameter. They originate at the renal pelvis, the funnel-shaped structure within each kidney, and descend through the abdominal cavity and pelvis, entering the bladder at an oblique angle through the vesicoureteral orifices. This angle helps to prevent the backflow of urine from the bladder into the kidneys.

The walls of the ureters are composed of three layers: an inner mucous membrane, a middle muscular layer, and an outer fibrous layer. The muscular layer is crucial for propelling urine through peristalsis, a series of wave-like muscular contractions. These contractions push urine downwards, even against gravity. The movement of urine is also aided by hydrostatic pressure from urine production in the kidneys and the relaxation of the bladder wall as it fills.

Problems with the ureters can include blockages caused by kidney stones, blood clots, or tumors. These blockages can lead to pain, difficulty urinating, and potential kidney damage if not treated. Inflammation of the ureters, known as ureteritis, can also occur. The ureters play a vital role in the urinary system's function of waste removal and fluid balance.