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Human Excretory System

This concept explains the human excretory system and the functions of the excretory system organs.

After reading the concept, students will be able to:

  • Identify different excretory organs from the human excretory system diagram.
  • Explain the Structure of kidney in brief.
  • Answer what is ureter?
  • Mention What is utrethra?


Each concept is explained to class 4 students using descriptions, illustrations, and concept maps. After you go through a concept, assess your learning by solving the two printable worksheets given at the end of the page.

Download the worksheets and check your answers with the worksheet solutions for the concept of the Human Excretory System and its functions provided in PDF format.

The organs that are involved in the process of disposing of waste from the body constitute the excretory system. It is a vital organ system of our body as it helps keep the body healthy by eliminating waste products in the form of urine.


Excretory System Organs and Their Functions:

1. Kidneys:

  • There are two kidneys inside our bodies, and these are the most important organ of the excretory system.
  • Kidneys are present at either side of our backbone below the chest and are reddish bean-shaped organs.
  • They have numerous renal pyramids (or kidney tissues), and those have nephrons.
  • Nephrons are the structural and functional units of the kidney.



  • The kidneys help filtrate the blood, and that is how they collect all unwanted toxic substances from the blood and form urine.
  • In this way, the blood gets purified.
  • Apart from filtrating toxic substances, the kidneys also help in the reabsorption of water from the urine and send it back to the blood.


2. Ureters:

  • Ureters are narrow tube-like structures that emerge from both the kidneys.
  • The ureters join the urinary bladder.


  •  When kidneys form sufficient urine, the urine moves to the urinary bladder via the ureter.

3. Urinary Bladder:

  • It is a pouch or balloon-like organ present in the lower abdomen.
  • The wall of the urinary bladder is made up of muscles.


  •  The urine is stored here temporarily.
  •  When the urinary bladder is filled up, we feel the urge to go to the bathroom.
  •  When we pass urine, the pouch-shaped bladder deflates to expel urine.

4. Urethra:

  • It is a small tube through which urine is excreted from the body.
  • It is the last part of the excretory system.


  •  The urine is excreted from the body through the urethra from the urinary bladder.


New Words:

Toxic: Something which is poisonous or harmful to us.

Expel: To discharge something outside.


Did You Know?

  • The liver is also an excretory organ because it helps to eliminate toxic substances from the blood.
  • The skin is also an excretory organ because it secrets sweat. Our body eliminates excess water, salts, and other toxic elements through sweat.
  • Lungs help in excretion by releasing carbon-di-oxide gas.
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