The process of voiding urine from the body to the outside
Urination is the process whereby urine is released from the body to the outside. In humans and other animals, the urinary system is responsible for the production of urine and its eventual excretion. The urinary system is comprised of kidneys, ureters, urinary bladder, and urethra. The initial process of urine production is filtration. The by-products and other compounds are filtered out. This is then followed by reabsorption wherein the nephron removes water and solutes from the pre-urine and then returns them to the circulating blood. From the kidneys, the urine passes through the ureter and stored in the urinary bladder. When it has to be excreted from the body, the urine passes through the urethra to the outside of the body. Thus, urination involves the urinary bladder and the urethra. Urination is typically a voluntary control. However, certain conditions, e.g. old age and neurological injury, make the process more of a reflex than voluntary. The inability to hold urine is called urinary incontinence whereas the inability to initiate urination is referred to as urinary retention.
Apart from the purpose of excreting metabolic wastes, urination is also used by certain animals to mark territories.
- urinate (verb, to pass urine; micturate)