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The human urinary system, also known as the urinary tract or renal system, consists of the kidneys, ureters, bladder, and the urethra. The purpose of the urinary system is to eliminate waste from the body, regulate blood volume and blood pressure, control levels of electrolytes and metabolites , and regulate blood pH .
The permanent organs of the adult are preceded by a set of structures which are purely embryonic, and which with the exception of the ducts disappear almost entirely before birth. These embryonic structures are on either side; the pronephros , the mesonephros and the metanephros of the kidney , and the Wolffian and Müllerian ducts of the sex ...
The urethra (pl.: urethras or urethrae) is the tube that connects the urinary bladder to the urinary meatus, [1] [2] through which placental mammals urinate and ejaculate. [3] In non-mammalian vertebrates, the urethra also transports semen but is separate from the urinary tract.
These animals possess an adult kidney derived from the metanephros. [24] The duct that connects the kidney to excrete urine in these animals is the ureter. [24] In placental mammals, it connects to the urinary bladder, whence urine leaves via the urethra. [25] In monotremes, urine flows from the ureters into the cloaca. [26]
Urology addresses diseases of kidney (and urinary tract) anatomy: these include cancer, renal cysts, kidney stones and ureteral stones, and urinary tract obstruction. [ 7 ] The word “ renal ” is an adjective meaning “relating to the kidneys”, and its roots are French or late Latin.
The nephron is the minute or microscopic structural and functional unit of the kidney.It is composed of a renal corpuscle and a renal tubule.The renal corpuscle consists of a tuft of capillaries called a glomerulus and a cup-shaped structure called Bowman's capsule.
The muscle helps maintain continence of urine along with the internal urethral sphincter which is under control of the autonomic nervous system.The external sphincter muscle prevents urine leakage as the muscle is tonically contracted via somatic fibers that originate in Onuf's nucleus and pass through sacral spinal nerves S2-S4 then the pudendal nerve to synapse on the muscle.
It is located at the junction of the urethra with the urinary bladder and is continuous with the detrusor muscle, [1] [2] but anatomically and functionally fully independent from it. [3] It is composed of smooth muscle , so it is under the control of the autonomic nervous system , specifically the sympathetic nervous system .