Page 103 - Ripples SCIENCE 7 - TEJPUR Edition 2024 Answer Key

11. Draw a labelled diagram of excretory system and state functions of its main parts.

Ans. Kidneys
The kidneys is a pair of purplish-brown organs

located below the ribs towards the middle of the
back. The kidneys remove urea from the blood

through tiny filtering units called nephrons.
When blood that contains waste is brought to the

kidneys, these nephrons remove urea, salt and
excess water from the blood. The filtered waste

forms a liquid called urine, which is transported
to the urinary bladder via ureters. The purified

blood returns to the circulatory system.
Ureters

The ureter is a thin muscular tube that carries urine from the kidney to the urinary
bladder. Muscles in the ureter walls keep tightening and relaxing. This forces urine

downwards and away from the kidneys.
Urinary Bladder

It is a sac-like structure and stores urine till it is expelled from the body by micturition.
Micturition is the act of expelling urine from the body. The bladder receives urine

from the kidneys through the urethra.
Urethra

This tube expels urine from the body. The urethra is shorter in females and longer
in males. In males, the urethra functions as a common path for semen that contains

sperms (reproductive cells) and urine. The opening of the urethra is guarded by
sphincter muscles that controls the opening and closing of urethra.

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