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Chapter
Four

FOR ONLINE READING ONLY
Excretion in animals

Introduction
There are different biochemical reactions which enable an organism to
carry out the life processes. Such reactions sometimes results into toxic
by-products. The toxic substances also called metabolic waste products
have to be removed from the body because they are harmful if allowed to
accumulate. The removal of metabolic waste products from the body of
an organism is known as excretion. In this chapter, you will learn about
the mechanism of excretion in the human body including excretory system,
organs and products. The competencies developed will enable you to properly
manage disorders of the excretory system and maintain health lifestyle by
avoiding the risk behaviours that can impair your excretory system.

Think which should be removed through excretion
because if they accumulate in the body
they become toxic. Excretion is the process
of removing metabolic or cellular waste
Concept of excretion products from the body of an organism.
Such waste products are called excretory
Task 4.1 products. The major excretory products
Search for information from library are carbon dioxide, excess water, salts,
and internet sources about the concept and nitrogenous compounds like ammonia,
of excretion in human. Summarize urea and uric acid. Carbon dioxide and
important points of what you have water are produced in the process of cellular
searched. respiration. Nitrogenous compounds
are formed from the breaking down of
All living organisms require nutrients to proteins. Dietary intake of salt rich foods,
obtain energy for various physiological salt absorption from the environment for
processes such as growth and movement. marine organisms like fish, cellular damage
These processes produce waste products and metabolic processes such as protein

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