Page 100 - Biology_Form_3

Excretion

Functions of the liver as an on the skin’s surface, aiding in maintaining
excretory organ the body’s internal balance.
(a) The liver breaks down excess amino
acids in a process called deamination. Apart from excretion, the skin also regulates
This process involves changing amino body temperature through sweating and
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group to poisonous ammonia. provides a barrier against pathogens,
dehydration, and physical injuries.
(b) The liver also performs detoxification
in which ammonia and other harmful Roles of the Skin in Excretion
compounds are converted to less toxic (a) Sweat production - the sweat glands
compounds. These compounds are excrete sweat, which contains water,
then excreted through urine. sodium chloride (salt), and small

(c) The liver is also involved in the amounts of urea and ammonia. This
formation of bile. When red blood helps in the removal of metabolic
cells break down green and yellow waste.
pigments are formed. These pigments (b) Regulation of body temperature-
are removed from the blood by the through the evaporation of sweat, the
liver and excreted in the bile. Bile is skin helps cool the body, preventing
stored in the gall bladder and used for overheating.
emulsifying fats. (c) Excretion of salt and water - excess

(d) The liver also breaks down hormones. salts and water are removed from the
The liver destroys almost all types of body through sweat helps the body to
hormones for the purpose of balancing maintain homeostasis.
them to the required level. Testosterone (d) Detoxification - Some toxins and heavy
and aldosterone are rapidly destroyed metals can be excreted through sweat,
whereas female sex hormones are thus reducing their concentration in
destroyed slowly. In this way the liver the body.
balances the levels of these hormones
in the body. (e) Maintenance of Electrolyte Balance
- By excreting excess salts, the skin
The Skin helps maintain the proper balance
The skin is one of the major excretory organs of electrolytes in the body which
in the human body, playing a crucial role in is essential for nerve and muscle
the removal of waste products. It contains function.
sweat glands that help in excretion through Generally, the skin plays a vital role in
the production of sweat. Sweat is composed excretion by removing waste through
of water, salts, and small amounts of urea, sweat, regulating body temperature, and
which are waste products of metabolism. maintaining homeostasis.
The excretion process occurs through pores

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BIOLOGY FORM 3 FINAL EDITED 16.09.2025.indd 93
BIOLOGY FORM 3 FINAL EDITED 16.09.2025.indd 93 KAMISHNA 23/10/2025 11:52:45

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