Human Excretory System

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Even the skin is an excretory organ in the human body! Sweat is considered a waste of our body. In this blog article, let us study the human excretory system in detail.


Living organisms generate waste in their bodies which has to be expelled. Basically, the human excretory system  is responsible for waste generation and elimination. It comprises a couple of kidneys, ureters, and a single urinary bladder and urethra.

human excretory system


Kidneys are the primary organs of the human excretory system. Every human being has a pair of kidneys. They are placed on each side of the spine, equivalent to the level of the liver. Kidneys are basically divided into three regions. The outer layer is called the renal cortex. The renal medulla is the inner layer. And finally, the renal pelvis which moves the urine from the kidney to the ureter. 

Structure of Nephron

The functional unit of a kidney is called the nephron. There are millions of nephrons in each kidney. They all function together for filtering blood and expelling waste products.

Bowman’s Capsule: It is the 1st part of nephron. The cup-shaped structure receives the blood vessels. Glomerular filtration happens here. Blood cells and proteins continue to remain in the blood. 

Proximal Convoluted Tubule: Bowman’s capsule stretches downwards to form the proximal tubule. Water and reusable materials from the blood gets reabsorbed back into it. 

Loop of Henle: The proximal tubule extends to form a u-shaped loop called Loop of Henle. Three of its major parts include the descending limb, the u-shaped bend and the ascending limb. Urine which becomes concentrated as water is absorbed in the area. While the descending limb is permeable to water, the ascending limb is impermeable to it.

Distal Convoluted Tubule: The Loop of Henle extends into the distal convoluted tubule. Kidney hormones are effective here.

Collecting Duct: The Distal Convoluted Tubule of every nephron leads to the collecting ducts. Together, they form the renal pelvis. The urine moves into the ureter and then into the bladder through the renal pelvis.


Acting as an extension of the renal pelvis, one ureter comes out of each kidney. It is basically a thin muscular tube which carries urine from the kidney to the bladder.

Urinary Bladder

The bladder is primarily a sac-like structure. It has the lining of a smooth muscle layer. The urine gets stored until micturition. The act of expelling urine from the body is called micturition. The urine is received by the bladder from the ureters, one from each kidney. It should be noted that the level of placement of the bladder differs in men and women. 


The tube which arises from the urinary bladder is called the urethra. Its primary function is to expel urine outside via micturition. The urethra is shorter in females and longer in males. To add on to it, in males, it acts as a common path for sperms and urine. The opening of the urethra is guarded by the sphincter.

Other Excretory Organs

The organs which perform excretion are: 

human excretory system 2


It is the largest organ in the body. The major function of the skin is to protect various organs of the body. In addition to this, skin excretes sweat as well. Compounds like Nacl and urea are eliminated by the skin. 


They are the primary respiratory organs. They assist in taking in oxygen and expelling carbon dioxide. A small amount of water is also eliminated in the form of vapor. 


Liver plays an important role in excreting waste from the body. For fats, alcohol, and drugs, it is the first line of defense in the human body. Even the kidney eliminates a few drugs. The liver helps in eliminating excess fats and cholesterol. Hence, it is vital for maintaining the health of our body.


The excretory system has several functions including:

  • It helps in eliminating waste products including urea, uric acid ammonia, and other chemical products through urine.
  • It helps in maintaining the osmotic level of blood and plasma.
  • It assists in maintaining the electrolyte balance in the body.
  • It helps in metabolism of the drugs which do not get metabolized in the river.

Check your knowledge

 Answer) It comprises a couple of kidneys, ureters, and a single urinary bladder and urethra.

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