Urinary system

The functions performed by the urinary system, also known as the renal system, can be considered as routine (i.e. production and excretion of urine), protective (i.e. elimination of toxins, reactive to blood pressure changes) or balancing (i.e. pH control in the blood and subsequently the urine, and electrolyte reabsorption during formation of urine). The term 'renal' simply denotes something that relates to or involves the kidneys. Clinically, urinary system functions are carefully considered in the context of age-related and developmental characteristics when prescribing medications, as medication dosages and their effectiveness are heavily dependent on renal function. The urinary system has an incredible capacity to cope with adversity; for example, when a diseased kidney is removed, the body can still function effectively with only one kidney. This chapter examines the structure and function of the urinary system and how different components of the system complement each other to maintain homeostatic balance through maintenance of acid-base balance in the blood, elimination of metabolic waste products and tight control of blood electrolyte balance. To function effectively, the kidneys"”the masters of these processes"”are heavily dependent on adequate blood perfusion, which is partially dictated by blood volume, a concept also explored in this chapter.