Anatomy Urinary System

---

---

Anatomy: Urinary System

The urinary system is made up of two kidneys, two ureters, a bladder, two sphincter muscles, the urethra, and various nerves and hormones that help to control the whole process. The male urinary system and the female urinary system are essentially the same.

Kidneys

Every day all of your blood is filtered through your kidneys about 400 times. This equates to the entire blood supply passing through the kidneys every five minutes.

As the blood passes through the walls of the kidneys, nephrons, which are tiny filtering units, remove urea and other waste products. There are over one million nephrons in the kidneys and they do the majority of the work in the urinary system, with the other organs mainly serving as passageways and storage spaces.

Kidneys (nephrons) are responsible for three other functions within the urinary system:

1. Controlling blood volume and blood pressure by removing water and solutes;

2. Regulating electrolytes and metabolites by reabsorbing sodium, phosphorus, and potassium;

3. Controlling blood pH by excreting selected amounts of various wastes, including H+.

Ureters

The ureters link the kidneys to the bladder and are from 8 to 10 inches long. Muscles in the ureters are constantly engaging to squeeze this liquid away from the kidneys. About every 10 seconds a little more urine is passed from the ureters to the bladder.

Bladder

The bladder is a hollow organ whose size varies depending on the amount of liquid it is holding. When operating properly, it can comfortably hold 2 cups of liquid for several hours.

Separating the bladder from the urethra is a sphincter that constricts tightly to keep urine from leaking from the bladder until the appropriate time.

Nerves communicate to the brain when the bladder is ready to be emptied. Another set of nerves relaxes the sphincter between the bladder and the urethra, thus allowing the urine to pass from the urinary system and out of the body.

On average an adult eliminates a liter and a half of urine a day. This, of course, varies depending on the amount of water consumed.

Formation of urine

The formation of urine in the urinary system is a multi-step process of filtration, reabsorption, and secretion. Once these steps are completed the urine is drained down the two long thin tubes called the ureters.

Summary

The urinary system is a complex system of filtration and elimination. When functioning well it supports healthy blood pressure, removes metabolic wastes from the blood and maintains electrolyte balance.

Here are tips to keep your urinary system healthy.

Also see the article on urinary tract infection remedies, which is one of the most common afflictions of the urinary system.