Final answer:
Involuntary discharge of urine is called urinary incontinence, not nocturia. It involves the micturition reflex, where the fullness of the bladder can override voluntary control, leading to leakage.
Step-by-step explanation:
The involuntary discharge of urine is not called nocturia. It is referred to as urinary incontinence, which is the unintentional leaking of urine. This condition can be due to several reasons, including an overactive bladder, stress incontinence, or an enlarged prostate gland. Additionally, the micturition reflex plays a critical role in urination; it is the process involving both involuntary and voluntary actions of the internal and external urethral sphincters. When bladder volume approaches between 300 to 400 mL, the ability to override the urge to void is compromised, potentially leading to incontinence. The term nocturia, on the other hand, refers to waking up during the night because one has to urinate.