E XCRETORY S YSTEM What do you think some of the functions of the urinary system are? How is the urinary system related to some of the other systems that you have already learned about?

F UNCTIONS OF THE E XCRETORY S YSTEM elimination of chemical/metabolic wastes from the body nitrogenous wastes (byproducts of chemical reactions that are no longer useful such as ammonia, urea, uric acid, creatinine) control the volume and composition of body fluids water-salt balance blood volume is closely associated with the salt balance of the body (i.e. the more salt in the blood, the greater the volume of blood and the greater the blood pressure) the kidneys are involved in regulating blood pressure and also maintain appropriate levels of certain ions in the blood acid-base balance the kidneys monitor and control blood pH through the excretion and reabsorption of certain ions the kidneys are the main organ of excretion principal job is the removal of urea and the regulation of water in the bloodstream

W ASTE P RODUCTS urea end product of amino acid metabolism in body cells water soluble primary end product of the urinary system excreted in urine ammonia end product of the deamination of amino groups very toxic to tissues converted to urea in the liver in land mammals creatinine end product from creatinine phosphate in muscle metabolism

S TRUCTURES OF THE E XCRETORY S YSTEM kidneys reddish brown organs approximately the size of a fist (4 inches long, 2 inches wide, 1 inch thick in an average sized adult) located on either side of the spinal column, anchored against the dorsal (back) body wall by connective tissue responsible for excretion of urine and the regulation of blood volume and pH renal vein carries blood from the kidneys back to the heart renal artery carries blood into the kidney

S TRUCTURES OF THE E XCRETORY S YSTEM C ONTINUED ureter muscular tube moves urine from the kidneys to the bladder through peristalsis urinary bladder urine storage, can hold up to 600 to 1000 mL of urine expands and contracts stretch receptors indicate when it is full, signal notifies the brain resulting in the desire to urinate urethra tube that connects the urinary bladder to the outside

D IAGRAM Kidney Renal Vein (OUT) Renal Artery (IN) Ureter Urinary Bladder Urethra