Anatomy & Physiology of the Renal System
The renal system, also known as the urinary system, consists of:
- 2 kidneys
- 2 ureters
- The bladder
- The prostate (in men)
- And lastly, the urethra
The female and male urinary system are very similar, differing only in the length of the urethra. The left ureter is approximately 28-34cm long and the right ureter is approximately 25-30cm long. In males, the urethra extends approximately 20cm as it must traverse the length of penis, whereas it is only 4cm long in females¹.
The purpose of the urinary system is to eliminate waste from the body, regulate blood volume & blood pressure, control levels of electrolytes & metabolites, and regulate blood pH. The urinary tract is the body’s drainage system for the eventual removal of urine².
The kidneys have an extensive blood supply which enters the kidneys via the renal artery & leaves the kidneys via the renal vein.
- Each kidney consists of functional units called nephrons which allows filtration of the blood entering via the renal artery.
- Following filtration, blood without waste exits via the renal vein.
- The filtered waste substance, known as urine, exits the kidney via the ureters which are tubes made of smooth muscle fibres that propel urine towards the bladder.
- Urine is stored in the bladder and subsequently expelled from the body by urination.
Each kidney consists of 3 regions:
- The renal cortex – this is the outer region containing approximately 1.25 million nephrons
- The renal medulla – this is the middle region containing 8-12 renal pyramids which functions as a collecting chamber for urine
- The renal pelvis – this is the inner region which receives urine through the major calyces to drain via the ureters.