Stretch of a full urinary blades is detected by?

Stretch of a full urinary blades is detected by stretch receptors.

The urinary bladder is a hollow, muscular organ that stores urine. When the bladder is empty, it is contracted and the walls are close together. As the bladder fills with urine, the walls stretch and the pressure inside the bladder increases. This stretching of the bladder walls activates stretch receptors, which send signals to the brain. The brain then interprets these signals as the need to urinate.