Micturition is the medical term for the process of urination or voiding urine from the urinary bladder through the urethra to the outside of the body. This process involves a complex interplay of neural, muscular, and hormonal factors that ensure the storage and expulsion of urine occurs in a controlled manner.
Micturition involves two main phases:
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Storage Phase: During this phase, the bladder fills with urine produced by the kidneys. The detrusor muscle (the muscle of the bladder) remains relaxed to allow the bladder to expand, while the internal and external sphincters remain contracted to prevent urine leakage.
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Voiding Phase: When the bladder is full, sensory nerves send signals to the brain, indicating the need to urinate. This leads to the conscious decision to void. During this phase, the detrusor muscle contracts to expel urine while the sphincters relax, allowing urine to flow through the urethra and out of the body.
Micturition is generally a voluntary process, though it can also be influenced by reflexes, particularly in infants or individuals with certain medical conditions.