Põielihase

Põielihase refers to the detrusor muscle, a smooth muscle that forms the wall of the urinary bladder. This muscle is responsible for the involuntary contraction that expels urine from the bladder during urination. The detrusor muscle is innervated by the autonomic nervous system, with parasympathetic stimulation causing contraction and sympathetic stimulation causing relaxation. When the bladder fills with urine, stretch receptors in its walls signal the nervous system, initiating the micturition reflex. This reflex involves the coordinated action of the detrusor muscle contracting and the internal and external urethral sphincters relaxing, allowing urine to flow out of the body. Conditions affecting the detrusor muscle, such as overactive bladder or underactive bladder, can lead to various urinary symptoms like urgency, frequency, and incontinence. The internal structure of the detrusor muscle consists of interlacing smooth muscle fibers, which enable it to effectively change shape and exert pressure on the bladder's contents. Its continuous tonic activity helps maintain bladder closure between voiding.