Life Processes in Living Organisms — Science STD 9 — Question
Maharashtra BoardEnglish MediumSTD 9ScienceLife Processes in Living Organisms3 Marks
Question
How does excretion occur in human beings?
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Answer
Removal of wastes from the body is very important and it is the excretory system that carries out this function.
The human excretory system consists of a pair of kidneys, a pair of ureters, the urinary bladder and the urethra. Urine is formed by the kidneys by separating the waste and unwanted excess substances from the blood.
The functional unit of the kidney that performs the basic function of filtration is called a nephron. The urea produced in the liver comes into the blood.
When the urea-containing blood comes into the glomerulus, it is filtered through capillaries and urea and other similar substances are separated from it.
Water molecules and small molecules of some other substances can cross the semipermeable membrane of Bowman’s capsule.
The solution accumulated in the cavity of Bowman’s capsule passes into the tubular part of the nephron. Here, molecules of water and some other useful substances are reabsorbed into the blood.
Urine is formed from the remaining solution which is full of waste materials. The urine is carried by the ureters and stored in the urinary bladder. Afterwards, urine is given out through the urethra.
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