Animals need oxygen and nutrients to create energy, so they have to distribute them to all parts of their body.

Animals use the energy to carry out the 3 vital functions: nutrition, reproduction and interaction.

What systems do animals use to transport the oxygen and the nutrients to all parts of their body?

To transport the oxygen, we use the respiratory system and the circulatory system.

To transport the nutrients, we use the digestive system and the circulatory system.


But, after using the oxygen and the nutrients to obtain energy, our body produces harmful substances (substances bad for our body). Those harmful substances are carbon dioxide and waste and they must be eliminated.

What systems do animals use to eliminate the carbon dioxide and the waste out of their bodies?

To eliminate carbon dioxide, we use the respiratory system.

To eliminate waste, we use the excretory system (urine), the digestive system (poo) and our skin (sweat).


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