The mechanisms behind urination

Micturition is the medical name for the process of voiding the bladder. The bladder is voided by a contraction of the detrusor, the muscle which surrounds it, coupled with the relaxation of the two sphincters of the urethra.

A simple explanation is that we can imaging that it is based on a reflex between strain sensors in the wall of the bladder and flow sensors in the urethra and the detrusor. The strain of having a full bladder triggers it to contract. The flow sensors detect when there is a flow of urine and feeds back to the bladder sensors to ensure the bladder stays contracted whilst there is urine still flowing. For adults, this reflex is a conscious reflex which is controlled by the brain. However, the co-ordination of the micturition and continence are subconsciously controlled and are integrated into other bodily processes.

Generally, micturition can be started on command nearly every time however a delay is observed in most people when in the presence of others. Causes of this include the detrusor not contracting sufficiently or a resistance in the flow through the urethra. This is usually caused by stress which causes the detrusor to relax and the sphincters to tighten. The syndrome is nearly always a social phobia and only rarely is a physical problem found.

If the cause is not addressed and the syndrome is fairly severe, dangerous conditions can occur – from the frequent need to urinate, blood in the urine and stomach pains. If you find you display any of these symptoms, it is imperative to visit a doctor for further investigation before you damage your health permanently.