Biology · Class 8–10

The Excretory System

See how your kidneys filter the blood and remove waste as urine.

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🧠 Remember it

The Excretory System

Kidneys filter blood → make urine → ureter → bladder → urethra. The filtering unit is the nephron. "Kidneys clean, bladder stores, urethra pours."

🌏 In real life

Doctors tell you to drink plenty of water in summer so your kidneys can flush out waste easily — dark yellow urine is a sign the kidneys are conserving water.

📝 Quick notes

  • Excretion removes toxic wastes (mainly urea) and balances water and salts.
  • Two kidneys filter the blood; each contains about a million tiny filters called nephrons.
  • Nephrons filter waste and reabsorb useful substances (glucose, most water) back into the blood.
  • Urine (water + urea + salts) flows from each kidney down a ureter to the urinary bladder.

🎯 Test yourself

What is the functional (filtering) unit of the kidney?

The nephron.

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See the animated, step-by-step The Excretory System lesson on Syllab

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