Urinary

Urinary is an adjective relating to urine or the urinary system. In physiology, it commonly describes the organs and processes involved in the production, storage, and elimination of urine. The adult human urinary system consists of the kidneys, ureters, bladder, and urethra. The kidneys filter blood, remove waste products, regulate fluid and electrolyte balance, and help maintain acid-base homeostasis. They also participate in hormone production, such as erythropoietin, and in the activation of vitamin D.

Most urine is produced in the kidneys by the nephrons, the kidney’s functional units. Blood enters the glomerulus where filtration occurs; the filtrate then passes through tubular segments where water, ions, and useful substances are reabsorbed, and waste products and certain substances are secreted into the tubule. The result is urine whose composition is adjusted by tubular processing and regulated by hormones such as antidiuretic hormone. The kidneys also influence blood pressure through the renin-angiotensin system.

Urine is transported from the kidneys to the urinary bladder via the ureters, two muscular tubes. The bladder stores urine until micturition, a process coordinated by neural circuits that manage bladder contractions and the external urethral sphincter, permitting voluntary urination in most healthy adults.

Common urinary conditions include urinary tract infections, kidney stones, urinary incontinence, and chronic kidney disease. Evaluation and management rely on clinical history, physical examination, urinalysis, urine culture when infections are suspected, and imaging studies as needed.