5. Overview of the urinary system

Question 1

what are the major functions of the kidneys

Answer 1

• excretion of waste products
• control of body fluid volume and composition of this fluid
• regulation of body fluid osmolality and electrolyte concentration
• regulation of acid-base
• regulation of arterial pressure
• erythropoetin
• regulation of 1,25-dihydroxyvitamin D3 production (calcitriol)
• gluconeogenesis

Question 2

what substances are secreted by the kidneys

Answer 2

• urea (from metabolism of amino acids)
• creatinine (from muscle creatinine)
• uric acid (from nucleic acids)
• bilirubin (and other end products of haemoglobin breakdown)
• hormone metabolites
• toxins
• drugs