Urinary system

The human urinary system, also known as the urinary tract or renal system, consists of the

Urine is formed in the kidneys through a filtration of blood. The urine is then passed through the ureters to the bladder, where it is stored. During urination, the urine is passed from the bladder through the urethra to the outside of the body.

800–2,000 milliliters (mL) of urine are normally produced every day in a healthy human. This amount varies according to fluid intake and kidney function.

Structure

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The urinary system refers to the structures that produce and transport urine to the point of excretion. In the human urinary system there are two kidneys that are located between the dorsal body wall and parietal peritoneum on both the left and right sides.

The formation of urine begins within the functional unit of the kidney, the nephrons. Urine then flows through the nephrons, through a system of converging tubules called collecting ducts. These collecting ducts then join together to form the minor calyces, followed by the major calyces that ultimately join the renal pelvis. From here, urine continues its flow from the renal pelvis into the ureter, transporting urine into the urinary bladder. The anatomy of the human urinary system differs between males and females at the level of the urinary bladder. In males, the urethra begins at the internal urethral orifice in the trigone of the bladder, continues through the external urethral orifice, and then becomes the prostatic, membranous, bulbar, and penile urethra. Urine exits through the external urethral meatus. The female urethra is much shorter, beginning at the bladder neck and terminating in the vaginal vestibule.

Development

Microanatomy

Under microscopy, the urinary system is covered in a unique lining called

• Regulate blood volume and composition (e.g. sodium, potassium and calcium)
• Regulate blood pressure.
• Regulate pH homeostasis of the blood.
• Contributes to the production of red blood cells by the kidney.
• Helps synthesize calcitriol (the active form of Vitamin D).
• Stores waste products (mainly urea and uric acid) before it and other products are removed from the body.

Urine formation

Average urine production in adult humans is about 1–2

The first step in urine formation is the filtration of blood in the kidneys. In a healthy human, the kidney receives between 12 and 30% of cardiac output, but it averages about 20% or about 1.25 L/min.

The basic structural and functional unit of the kidney is the

The urinary system is under influence of the circulatory system, nervous system, and endocrine system.

Urination, also sometimes referred to as micturition, is the ejection of

Urologic disease can involve congenital or acquired dysfunction of the urinary system. As an example, urinary tract obstruction is a urologic disease that can cause urinary retention.

Diseases of the kidney tissue are normally treated by

Diseases of other bodily systems also have a direct effect on urogenital function. For instance, it has been shown that

Diabetes also can have a direct effect in urination due to peripheral neuropathies, which occur in some individuals with poorly controlled blood sugar levels.^[7]

Some cancers also target the urinary system, including bladder cancer, kidney cancer, ureteral cancer, and urethral cancer. Due to the role and location of these organs, treatment is often complicated.^{[citation needed]}

History

• Excretory system
• Major systems of the human body

References

External links

The Wikibook Human Physiology has a page on the topic of: The Urinary System

The Wikibook Anatomy and Physiology of Animals has a page on the topic of: Urinary System

Library resources about
Urinary system

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