Chapter 20 Urinary System

Function Waste removal Maintains water and electrolyte balance Regulates pH

Structure 2 Kidneys Reddish brown Bean shaped Lateral to vertebral column Structure Cortex – outer edge Medulla – internal tissue containing nephrons Nephrons – tiny tubules that allow kidneys to function

Structure Continued

Structure Continued 2 Ureters – tube from each kidney to the bladder Bladder – holding tank Urethra – tube to the outside of the body

Urine Formation Nephrons Regulate water and electrolyte concentrations Remove waste from the blood

Urine Formation Continued Urine Content Not Found in Plasma Urea – breakdown of amino acids Uric Acid – by product of amino acid metabolism High sulfate High phosphate *All glucose is supposed to get reabsorbed *95% water

Water Intake Water Output 30% = moist food 10% = metabolism Regulated by thirst Hypothalamus Water loss = increase in extracellular osmotic pressure Thirst occurs at 1% of total body (or when the body is dehydrated by 1%) 60% = urine 6% = feces 6% = sweat 28% = evaporation from skin/breathing Regulated by urine production ADH (antidiuretic hormone) present

Electrolyte Intake Electrolyte Output Food Beverages Metabolic reactions Salt cravings Sweat Feces Kidney and urine production Hormone aldosterone (controls water excretion)