What is the Renal System | What is the Function of the Renal System
The urinary system consists of the kidneys, ureters, urinary bladder and urethra. The
kidneys filter the blood to remove wastes and produce urine. The ureters, urinary bladder and urethra together form the urinary tract, which acts as a plumbing system to drain urine from the kidneys, store it, and then release it during urination. Besides filtering and eliminating wastes from the body, the urinary system also maintains the homeostasis of water, ions, pH, blood pressure, calcium and red blood cells. The kidneys have extensive blood supply via the renal arteries which leave the kidneys via the renal vein.
Kidneys: The kidneys are a pair of bean shaped organs found along the posterior wall of the abdominal cavity. The left kidney is located slightly higher than the right kidney because the right side of the liver is much larger than the left side. The kidneys, unlike the other organs of the abdominal cavity, are located posterior to the peritoneum and touch the muscles of the back. The kidneys are surrounded by a layer to stretch to hold anywhere from 600 to 800 millilitres of urine.
Urethra: The urethra is the tube through which urine passes from the bladder to the exterior of the body. The female urethra is around 2 inches long and ends inferior to the clitoris and superior to the vaginal opening. In males, the urethra is around 8 to 10 inches long and ends at the tip of the penis. The urethra is also an organ of the male reproductive system as it carries sperm out of the body through the penis. The flow of urine through the urethra is controlled by the internal and external urethral sphincter muscles. The internal urethral sphincter is made of smooth muscle and opens involuntarily when the bladder reaches a certain set level of distention. The opening of the internal sphincter results in the sensation to have needed to urinate. The external urethral sphincter is made of skeletal muscle and may be opened to allow urine to pass through the urethra or may be held closed to delay urination. There are several functions of the
Urinary System | Renal Urinary System | Kidney Renal System
- Removal of waste product from the body (mainly urea and uric acid).
- Regulation of electrolyte balance (e.g. sodium, potassium and calcium).
- Regulation of acid-base homeostasis
- Controlling blood volume and maintaining blood pressure.
- Production of Hormones. (e.g. Erythropoietin, Calcitriol, Renin).