Final answer:
Micturition, or urination, involves voiding urine through the urethra, a muscular tube connected to the urinary bladder. It is regulated by involuntary and voluntary sphincters and shows anatomical differences between males and females.
Step-by-step explanation:
Micturition involves the process of voiding urine through a specific organ known as the urethra. During urination, the bladder contracts to push urine into the urethra, which then expels it from the body. The urethra is a muscular tube that plays a vital role in excretion of urine. It begins at the bladder and extends to the external urethral orifice. Significant to note is that the anatomy of the urethra shows distinctions between males and females, due to the male urethra's dual role in transporting both urine and semen.
The control of micturition involves both involuntary and voluntary actions. An involuntary internal sphincter made of smooth muscle and a voluntary external sphincter made of skeletal muscle regulate the flow of urine. The bladder, which can hold up to 500-600 mL of urine, signals to these sphincters to relax when a certain volume of urine is present. Micturition is usually under conscious control, allowing us to decide when to urinate. However, when the bladder volume approaches 300 to 400 mL, urges become more insistent and may be difficult to override, potentially leading to incontinence.