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The urinary system (also called excretory system
Excretory system

This system involves the kidneys and the liver which is not part of the system but creates most of the excreted waistLeifangThe excretory system excretes wastes....
 or the genitourinary system) is the organ system that produces, stores, and eliminates urine
Urine

Urine is a liquid waste product of the body secreted by the kidneys by a process of filtration from blood called urination and excreted through the urethra....
. In humans it includes two kidney
Kidney

The kidneys are Organ that have numerous biological roles. Their primary role is to maintain the homeostasis balance of bodily fluids by filtering and secreting Metabolomics#Metabolitess and minerals from the blood and excreting them, along with water , as urine....
s, two ureter
Ureter

In human anatomy, the ureters are muscular ducts that propel urine from the kidneys to the urinary bladder. In the adult, the ureters are usually long....
s, the bladder
Urinary bladder

In anatomy, the urinary bladder is a solid, muscle, and distensible organ that sits on the pelvic floor in mammals. It is the organ that collects urine excreted by the kidneys prior to disposal by urination....
, and the urethra
Urethra

In anatomy, the urethra is a tube which connects the urinary bladder to the outside of the body. The urethra has an excretory function in both sexes to pass urine to the outside, and also a reproductive function in the male, as a passage for semen....
. The analogous organ in invertebrates is the nephridium
Nephridium

Nephridia are invertebrate organs which function similarly to kidneys. They remove Metabolism wastes from an animal's body. They are present in many different invertebrate lines....
.

kidneys are bean shaped organs, which lie in the abdomen, rump or retroperitoneal to the organs of digestion, around or just below the ribcage and close to the lumbar spine.






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The urinary system (also called excretory system
Excretory system

This system involves the kidneys and the liver which is not part of the system but creates most of the excreted waistLeifangThe excretory system excretes wastes....
 or the genitourinary system) is the organ system that produces, stores, and eliminates urine
Urine

Urine is a liquid waste product of the body secreted by the kidneys by a process of filtration from blood called urination and excreted through the urethra....
. In humans it includes two kidney
Kidney

The kidneys are Organ that have numerous biological roles. Their primary role is to maintain the homeostasis balance of bodily fluids by filtering and secreting Metabolomics#Metabolitess and minerals from the blood and excreting them, along with water , as urine....
s, two ureter
Ureter

In human anatomy, the ureters are muscular ducts that propel urine from the kidneys to the urinary bladder. In the adult, the ureters are usually long....
s, the bladder
Urinary bladder

In anatomy, the urinary bladder is a solid, muscle, and distensible organ that sits on the pelvic floor in mammals. It is the organ that collects urine excreted by the kidneys prior to disposal by urination....
, and the urethra
Urethra

In anatomy, the urethra is a tube which connects the urinary bladder to the outside of the body. The urethra has an excretory function in both sexes to pass urine to the outside, and also a reproductive function in the male, as a passage for semen....
. The analogous organ in invertebrates is the nephridium
Nephridium

Nephridia are invertebrate organs which function similarly to kidneys. They remove Metabolism wastes from an animal's body. They are present in many different invertebrate lines....
.

Physiology


Kidney

The kidneys are bean shaped organs, which lie in the abdomen, rump or retroperitoneal to the organs of digestion, around or just below the ribcage and close to the lumbar spine. The organ is about the size of a human fist and is surrounded by what is called peri-nephric fat, and situated on the superior pole of each kidney is an adrenal gland
Adrenal gland

In mammals, the adrenal glands are the star-shaped endocrine glands that sit on top of the kidneys; their name indicates that position . They are chiefly responsible for regulating the stress response through the biosynthesis of corticosteroids and catecholamines, including cortisol and adrenaline, respectively....
. The kidneys receive their blood supply of 1.25 L/min (25% of the cardiac output
Cardiac output

Cardiac output is the volume of blood being pumped by the heart, in particular by a ventricle in a minute. This is measured in dm3 min-1 ....
) from the renal arteries which are fed by the Abdominal aorta
Abdominal aorta

The abdominal aorta is the largest artery in the abdominal cavity. As part of the aorta, it is a direct continuation of descending aorta ....
. This is important because the kidneys' main role is to filter water soluble waste products from the blood. The other attachment of the kidneys are at their functional endpoints the ureters, which lies more medial
Anatomical terms of location

Standard anatomical terms of location are employed in sciences dealing with the anatomy of animals to avoid ambiguities which might otherwise arise....
 and runs down to the trigone of the bladder
Urinary bladder

In anatomy, the urinary bladder is a solid, muscle, and distensible organ that sits on the pelvic floor in mammals. It is the organ that collects urine excreted by the kidneys prior to disposal by urination....
.

Functionally the kidney performs a number of tasks
Renal physiology

Renal physiology is the study of the physiology of the kidney. This encompasses all functions of the kidney, including reabsorption of glucose, amino acids, and other small molecules; regulation of sodium, potassium, and other electrolytes; regulation of fluid balance and blood pressure; maintenance of acid-base balance; and the production...
. In its role in the urinary system it concentrates urine, plays a crucial role in regulating electrolyte
Electrolyte

An electrolyte is any substance containing free ions that behaves as an electrical conductor medium. Because they generally consist of ions in solution, electrolytes are also known as ionic solutions, but molten electrolytes and solid electrolytes are also possible....
s, and maintains acid-base homeostasis
Acid-base homeostasis

Acid-base homeostasis is the part of human homeostasis concerning the proper balance between acids and Chemical base, in other words the pH. The body is very sensitive to its pH level....
. The kidney excretes and re-absorbs electrolyte
Electrolyte

An electrolyte is any substance containing free ions that behaves as an electrical conductor medium. Because they generally consist of ions in solution, electrolytes are also known as ionic solutions, but molten electrolytes and solid electrolytes are also possible....
s (e.g. sodium
Sodium

Sodium is an element which has the symbol Na , atomic number 11, atomic mass 23 amu , and a common oxidation number +1. Sodium is a soft, silvery white, highly reactive element and is a member of the alkali metals within "group 1" ....
, potassium
Potassium

Potassium is a chemical element. It has the symbol K , atomic number 19, and atomic mass 39.0983. Potassium was first isolated from potash, hence the name....
 and calcium
Calcium

Calcium is the chemical element with the symbol Ca and atomic number 20. It has an atomic mass of 40.078 amu. Calcium is a soft grey alkaline earth metal, and is the fifth most abundant element by mass in the earth's Crust ....
) under the influence of local and systemic hormones. pH
PH

pH is a measure of the Acid or Base of a solution. It is defined as the cologarithm of the Activity of dissolved hydrogen ions . Hydrogen ion activity coefficients cannot be measured experimentally, so they are based on theoretical calculations....
 balance is regulated by the excretion of bound acids
Titratable acid

Titratable acid is a term to describe acids such as phosphoric acid, sulfuric acid which are involved in renal physiology.It is used to explicitly exclude ammonium as a source of acid, and is part of the calculation for net acid excretion....
 and ammonium
Ammonium

The ammonium cation is a positively electric charge polyatomic ion of the chemical formula NH4+. It has a formula weight of 18.05 and is formed by protonation of ammonia ....
 ions. In addition, they remove urea
Urea

Urea is an organic compound with the chemical formula 2carbonoxygen.Urea is also known by the International Nonproprietary Name carbamide, as established by the World Health Organization....
, a nitrogenous waste product from the metabolism
Metabolism

Metabolism is the set of chemical reactions that occur in living organisms in order to maintain life. These processes allow organisms to grow and reproduce, maintain their structures, and respond to their environments....
 of proteins from amino acid
Amino acid

In chemistry, an amino acid is a molecule containing both amine and carboxyl functional groups. These molecules are particularly important in biochemistry, where this term refers to alpha-amino acids with the general formula H2NCHRCOOH, where R is an organic substituent....
s. The end point is a hyperosmolar
Osmole (unit)

Osmolarity is a measure of solute concentration, defined as the number of osmole s of solute per liter of solution . The osmolarity of a solution is usually expressed as Osm , in the same way that the molarity of a solution is expressed as "M" ....
 solution carrying waste for storage in the bladder prior to urination
Urination

Urination, also known as micturition, voiding, and, more rarely, emiction, is the process of disposing urine from the urinary bladder through the urethra to the outside of the body....
.

Human
Human

A human being, also human or man, is a member of a species of bipedalism primates in the family Hominidae . Mitochondrial DNA evidence indicates that modern humans originated in east Africa about 200,000 years ago....
s produce about 2.9 liter
Litér

Lit?r is a village in Veszpr?m , Hungary.External links ...
s of urine over 24 hours, although this amount may vary according to circumstances. Because the rate of filtration at the kidney is proportional
Proportionality (mathematics)

In mathematics, two quantity are called proportional if they vary in such a way that one of the quantities is a constant multiple of the other, or equivalently if they have a constant ratio....
 to the glomerular filtration rate, which is in turn related to the blood flow through the kidney, changes in body fluid status can affect kidney function. Hormones exogenous and endogenous to the kidney alter the amount of blood flowing through the glomerulus
Glomerulus

A glomerulus is a capillary tuft surrounded by Bowman's capsule in nephrons of the vertebrate kidney. It receives its blood supply from an afferent arteriole of the renal circulation....
. Some medication
Medication

A pharmaceutical drug, also referred to as medicine or medicament, can be loosely defined as any substance intended for use in the diagnosis, cure, mitigation, treatment, or prevention of disease....
s interfere directly or indirectly with urine production. Diuretic
Diuretic

A diuretic is any drug that elevates the rate of urination and thus provides a means of forced diuresis. There are several categories of diuretics....
s achieve this by altering the amount of absorbed or excreted electrolytes or osmalites
Osmole (unit)

Osmolarity is a measure of solute concentration, defined as the number of osmole s of solute per liter of solution . The osmolarity of a solution is usually expressed as Osm , in the same way that the molarity of a solution is expressed as "M" ....
, which causes a diuresis
Diuresis

Diuresis is the increased production of urine by the kidney....
.

Bladder

In human
Human

A human being, also human or man, is a member of a species of bipedalism primates in the family Hominidae . Mitochondrial DNA evidence indicates that modern humans originated in east Africa about 200,000 years ago....
s and other related organisms, the urinary bladder
Urinary bladder

In anatomy, the urinary bladder is a solid, muscle, and distensible organ that sits on the pelvic floor in mammals. It is the organ that collects urine excreted by the kidneys prior to disposal by urination....
 is a hollow muscular organ shaped like a balloon, located in the retroperitoneally pelvis. The bladder stores urine. The maximum that it can hold is one liter. It swells into a round shape when it is full and gets smaller when empty. In the absence of bladder disease, it can hold up to 300 ml of urine comfortably for two to five hours. The epithelial tissue associated with the bladder is called transitional epithelium. Normally the bladder is sterile.

Sphincter
Sphincter

A sphincter is a structure, usually a circular muscle, that normally maintains constriction of a natural body passage or orifice and which relaxes as required by normal physiological functioning....
s (circular muscles) regulate the flow of urine from the bladder. The bladder itself has a muscular layer (detrusor muscle) that, when contracted, increases pressure on the bladder and creates urinary flow.

Urination
Urination

Urination, also known as micturition, voiding, and, more rarely, emiction, is the process of disposing urine from the urinary bladder through the urethra to the outside of the body....
 is a conscious process, generally initiated by stretch receptors in the bladder wall which signal to the brain that the bladder is full. This is felt as an urge to urinate. When urination is initiated, the sphincter relaxes and the detrusor muscle contracts, producing urinary flow.

Urethra

The endpoint of the urinary system is the urethra. Typically the urethra in humans is colonised by commensal bacteria below the external urethral sphincter. The urethra emerges from the end of the penis
Penis

The penis is an external sex organ of certain biologically male organisms, in both vertebrates and invertebrates.The penis is a reproductive organ, technically an intromittent organ, and for Eutheria, additionally serves as the external organ of urination....
 in males and between the clitoris
Clitoris

The clitoris is a sex organ that is present only in female mammals. In humans, the visible button-like portion is located near the anterior junction of the labia minora, above the opening of the urethra and vagina....
 and the vagina
Vagina

The vagina is a fibromuscular cylinder tract leading from the uterus to the exterior of the body in female placental mammals and marsupials, or to the cloaca in female birds, monotremes, and some reptiles....
 in females.

See also

  • Urothelium
    Urothelium

    The urothelium is the Biological tissue layer that lines much of the urinary tract, including the renal pelvis, the ureters, the Urinary bladder, and parts of the urethra....
  • Major systems of the human body
  • Urologic disease
    Urologic disease

    Urologic disease can involve congenital or acquired dysfunction of the urinary system.Kidney diseases are normally investigated and treated by nephrologists, while the specialty of urology deals with problems in the other organs....