Detruzorkontraktion

Detruzorkontraktion, or detrusor contraction, is the contraction of the detrusor muscle, the smooth muscle layer of the urinary bladder, which reduces bladder volume and facilitates urine expulsion during micturition. The detrusor muscle is arranged in multiple layers and, when contracted, increases bladder pressure to push urine through the urethra. During the storage phase, the detrusor relaxes to accommodate urine; during voiding, a coordinated contraction occurs to empty the bladder.

Neural control of detrusor contraction involves a balance between storage and voiding pathways. Storage is promoted by sympathetic input via the hypogastric nerve, which relaxes the detrusor mainly through β3-adrenoceptors. Voiding is driven by parasympathetic activity through the pelvic nerves, which release acetylcholine that binds muscarinic M3 receptors on detrusor cells, triggering an increase in intracellular calcium and muscle contraction. Afferent bladder stretch signals travel to the sacral spinal cord to initiate a micturition reflex, and higher brain centers, notably the pontine micturition center, coordinate the timing of detrusor contraction with relaxation of the internal and external urethral sphincters.

Clinical relevance includes conditions of abnormal detrusor contraction. Detrusor overactivity involves involuntary contractions during bladder filling and can cause urge incontinence. Detrusor underactivity or areflexia reduces contractile force and can lead to urinary retention. Diagnosis often uses urodynamic studies, and treatment may include antimuscarinic or beta-3 adrenergic agents to modulate detrusor activity, neuromodulation, or surgical approaches for refractory cases.