The renal system

The focus of this chapter is the renal system and the clinical skills that are associated with renal dysfunction. By the end of this chapter you will be knowledgeable in relation to these skills and your new knowledge will be underpinned by up-to-date evidence-based best practice. It is anticipated that you will be able to do the following once you have read and studied this chapter: ● Understand urine sampling techniques and urine testing methods and their significance in clinical practice. ● Understand the various procedures and investigations that the infant, child, or young person may have to endure for renal system evaluation. The urinary system is important in maintaining the correct water and electrolyte concentrations in the body. Waste products and excess water and ions are eliminated from the body in the urine. The kidneys are situated on either side of the vertebral column in the abdomen. The ureter, renal blood vessels, nerves, and lymphatics enter the kidney at a cleft on the medial side called the hilum. The adrenal gland lies on top of the kidney. The outside of each kidney is lined by: ● The renal capsule—a layer of collagen fibres. ● The adipose capsule—a layer of fat. ● The renal fascia—a layer of dense connective tissue. These three layers of tissue protect and support the kidney. The inside of each kidney contains an outer area (the cortex) and an inner area (the medulla). The cortex is lighter in colour compared to the dark reddish-brown medulla. The medulla contains cone-shaped areas of tissue called the medullary pyramids, which point towards the hilum. The cortex extends in between the medullary pyramids forming the renal columns. Urine forms at the tip of the pyramids (papillae) and drains into the minor calyx, then into a larger major calyx. Two or three major calyces join together to form the renal pelvis, a funnel-shaped chamber that leads into the ureter. Nephrons are the functional units of the kidney, the structures where urine is formed.