Top 25 Urinary System Fun Facts

Urinary System Fun Facts
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Urinary System Fun Facts: Another vital organ system of the human body that is involved in the conservation of water and excretion of waste products and by-products of metabolism is the Urinary system.

The Urinary system is responsible for cleaning or filtering the blood of toxic metabolites and waste products to produce Urine that Is finally excreted out of the human body.

Apart from this primary function, the urinary system also plays a role in other functions of the body, which is discussed further in this article.

Top 25 Urinary System Fun Facts


The Urinary system also is known as the renal system, is composed of different components.

  • The Urinary system consists of a pair of kidneys located in the upper abdomen.
  • It also comprises of a pair of ureters which carry filtered urine to the Urinary bladder for storage.
  • Once full, the urinary bladder empties urine containing waste products and toxic metabolites to the exterior via the Urethra, which is the opening of the urinary system.


The Kidneys, which are the principal organs of the urinary system resemble kidney beans.

  • The kidneys resemble the kidney beans in shape and color and are situated along the posterior wall of the abdomen.
  • The two kidneys are slightly different in terms of placement, with the right kidney being slightly lower than the left.
  • The adrenal glands that secrete hormones and perform endocrine functions are located on top of each kidney.


The Kidneys are involved in the removal of toxic and metabolic wastes, as well as regulation of fluid and electrolyte balance.

  • The kidneys are the main organs that filter the blood of metabolic waste products. The urine is formed within the kidneys and is then emptied into the ureters.
  • The amount of solutes present in the blood is regulated by the Kidneys.
  • Depending on the body’s needs the kidneys help conserve or eliminate water and electrolytes from the body.


The Kidneys are also involved in the regulation of pH or acid-base balance and blood pressure.

  • An increase in H+ ions leads to acidity, while an increase in HCO3- ions leads to the production of alkalinity.
  • The kidneys have the adrenal glands situated on their anterior ends. These glands secrete hormones as part of the endocrine system that controls blood volume.
  • The control of blood volume and peripheral resistance in turns controls blood pressure of the body.


The renal system also controls the formation of red blood cells and other metabolic functions.

  • The Kidneys also perform the endocrine function by releasing a hormone known as erythropoietin.
  • This hormone acts on the bone marrow to stimulate the production of red blood cells.
  • It is also involved in the process of gluconeogenesis, vitamin D production, and detoxification of the blood.


There are 3 layers of connective tissue supporting each kidney externally.

  • The renal fascia is the outermost layer of fibrous connective tissue that holds the adrenal gland and the kidney to the surrounding area.
  • The perirenal fat capsule surrounds the kidney and protects against injury.
  • The fibrous capsule is a transparent mass that protects the kidneys against infections in the surrounding regions.


The interior of the kidney is made up of 3 parts: the cortex, medulla and the pelvis.

  • A kidney section reveals 3 distinct layers. The outermost layer is the cortex, which is light in color and granular.
  • The middle layer is the medulla, which is darker and color and is divided into cone-shaped pyramids called the medullary or renal pyramids.
  • The renal pelvis is a funnel-shaped tube that connects the medulla to the hilum towards the ureters.


The kidneys are innervated with a rich supply of blood vessels.

  • The renal artery delivers blood to the kidney for filtration and detoxification. About 1200ml of blood is delivered to the kidneys each minute under normal resting conditions.
  • The renal artery further divides into five segmental arteries when it enters the kidney, and then further subdivides into interlobar arteries.
  • The arterioles then connect to the renal veins which further empties the filtered blood into the inferior vena cava.


The structural and functional unit of the kidney is the nephron.

  • Around a million nephrons are found in each kidney that forms the blood-processing unit of the renal system.
  • Collecting ducts collect urine formed in the nephrons and carry it to the renal pelvis.
  • It is the main structure in which urine is formed inside the kidney.


The Nephron is made up of two main parts.

  • Each nephron is made up of a bunch of capillaries known as the glomerulus.
  • The other part of the nephron is the renal tubule that has a cup-shaped or U-shaped region called the Bowman’s Capsule.
  • The Glomerulus and the renal tubule together are known as the renal corpuscle.


There are two main types of Nephrons present in the kidney.

  • Nephrons can be divided into two categories – cortical nephrons and juxtamedullary nephrons.
  • 85% of the Nephrons present in the kidney are the cortical nephrons and are located entirely in the cortex.
  • The juxtamedullary nephrons are located closer to the cortex-medulla junctional region and are involved in the production of concentrated urine.


Filtration of the blood takes place through the filtration membrane in the glomerular capsule.

  • The glomerular capsule contains a thin porous membrane known as the filtration membrane.
  • It allows the passage of water and solute molecules smaller than plasma proteins.
  • It plays a role in the filtration of blood and formation of urine in the capsule.


The process of filtration of blood and formation of urine in the nephron is known as glomerular filtration.

  • In this process, hydrostatic pressure causes fluids and solutes to pass through the filtration membrane passively. This process does not consume metabolic energy.
  • Any solutes or molecules smaller than 3nm in diameter for, eg. Water, glucose, nitrogenous compounds or wastes, and amino acids are easily able to pass through the filtration membrane during the process of glomerular filtration.
  • Molecules that are larger than 5nm in size are unable to pass through the filtration membrane. Therefore, any presence of proteins or blood cells in the urine usually indicates an issue with the process (or) with the filtration membrane.
Suggested Reading: Cell Wall Functions


The glomerular filtration rate indicates the functional capacity of the nephron.

  • The glomerular filtration rate, also known as GFR, is the sum of all individual filtration rates of all nephrons in the kidneys.
  • In a normal healthy human being, the GFR is estimated to be 100-125 ml per minute.
  • The GFR is calculated using radionuclide methods and is an indicator of proper kidney or nephron functioning.


The urinary bladder is located in the pelvis and is responsible for the storage of urine.

  • The bladder is situated between the pelvic bones and is a muscular hollow organ.
  • The bladder expands as urine is collected in it, until the point when it is full.
  • When the bladder is full, the contents are expelled out by the process of micturition or urination and is under the control of the nervous system.


There are 3 muscle groups that control the functioning of the urinary bladder.

  • The urethra is the opening of the urinary bladder to the exterior and also acts as a muscular structure that controls the bladder.
  • The bladder neck is the region where the urethra connects with the bladder and contains the second muscle group called the internal sphincter. It helps the urine to remain in the bladder.
  • The third muscle group, also known as the external sphincter or pelvic floor muscles surround the urethra, also plays a role in bladder control.


The process of micturition or urination by emptying the bladder is under the control of the brain and nervous system.

  • At the time of urination, signals from the brain via the nerves, initiate the muscles in the bladder to tighten.
  • These nerve signals cause micturition or urination to begin under the control of the nervous system.
  • Meanwhile, the brain also sends signals to the sphincters to relax, causing the urine to exit through the urethra.


The renal tubule in the nephron is made up of 3 parts.

  • The renal tubule is comprised of three regions: the Proximal tubule, Loop of Henle, and the distal tubule.
  • The Proximal tubule is the first part of the renal tubule and is also the longest part through which urine travels.
  • The loop of Henle is the only part of the renal tubule that enters into the medulla. It is made up of two limbs – the descending limb and the ascending limb.
  • The distal tubule is the final region through which the urine flows.


The amount of urine that a human being produces depends on several factors.

  • The factors that urine production depends on include how much the individual consumes food and water.
  • It also depends on how much fluid is lost through sweating and breathing from the body.
  • At times, particular medications and conditions can influence the amount of urine output produced.


Obstructive nephropathy or uropathy is a disorder that affects the urinary system.

  • It is one of the most common issues of the urinary system affecting the kidneys and the urinary tract.
  • It is caused by an obstruction in any part of the urinary tract or the kidney.
  • If detected early, it is easily reversible.


Anuria is a condition in which urine output declines significantly below the average level.

  • An abnormal level of urine output that is much below 50ml/day indicates an issue with the filtration membrane in the nephron or the glomerular filtration rate.
  • Other conditions that can cause anuria include acute nephritis and transfusion reactions.


The filtrate that forms the urine is rich primarily in Sodium ions.

  • The most abundant cation in the filtrate of the nephron is the Sodium ion.
  • 80% of energy reserves are used up in the process of sodium reabsorption.
  • It is an active process and occurs via the transcellular route.


The antidiuretic hormone controls the reabsorption of water from the filtrate.

  • The antidiuretic hormone or ADH controls the urine output and concentration by controlling the process of water reabsorption from the filtrate.
  • It inhibits diuresis, which means it aids in decreasing the urine output and conserving water by increasing water reabsorption from the filtrate.


Diuretics are chemicals or medical supplements that increase the urine output.

  • Diuretics are substances that can enhance or increase urine output by inhibiting the release of the antidiuretic hormone.
  • They can also work by decreasing sodium ion reabsorption, which eventually leads to a decrease in water reabsorption as well.
  • Some natural diuretics include caffeine found in coffee or tea and many drugs that are usually prescribed for conditions such as hypertension or cardiac disorders.


Urochrome is a pigment that gives urine its yellowish color.

  • Urochrome is produced after the destruction of the hemoglobin pigment found in the blood.
  • When the blood is filtered, the resultant urine has a yellowish color due to the presence of urochrome.
  • The color may be darker, depending on the concentration of urochrome in the urine.

The urinary system plays an essential role in the elimination of metabolic and toxic wastes from the human body and helps maintain the status of homeostasis. It works together with the other organ systems to ensure the proper functioning of the human body.

Cite this article as: "Top 25 Urinary System Fun Facts," in Bio Explorer, May 8, 2021,

Key References

  • “The Urinary System” – Accessed November 03, 2019. Link.
  • “Kidney Anatomy” – PH School. Accessed November 03, 2019. Link.
  • “KIDNEYS AND URINARY SYSTEM” – Gopinathan Nair. Accessed November 03, 2019. Link.
  • “The Urinary Tract and How It Works”. Accessed November 03, 2019. Link.

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