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The Human Body - Introduction to Digestive and Respiratory systems

Grade 3ICSE

Review the key concepts, formulae, and examples before starting your quiz.

🔑Concepts

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The Digestive System is a group of organs that work together to break down food into simpler substances so that the body can use it for energy and growth.

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Digestion starts in the mouth where teeth chew food and mix it with saliva. The food then travels down the food pipe (esophagus) to the stomach.

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In the stomach, food is mixed with digestive juices to form a thick soup-like paste, which then moves into the small intestine where nutrients are absorbed.

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The Respiratory System helps us breathe. It consists of the nose, windpipe (trachea), and the lungs.

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We breathe in Oxygen (O2O_2) from the air, which is needed by our body to produce energy from the food we eat.

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We breathe out Carbon Dioxide (CO2CO_2), which is a waste product formed in our body.

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The diaphragm is a large, dome-shaped muscle below the lungs that helps in the process of breathing.

📐Formulae

Food+Oxygen(O2)→Energy+CarbonDioxide(CO2)+WaterFood + Oxygen (O_2) \rightarrow Energy + Carbon Dioxide (CO_2) + Water

Inhalation=Taking in O2Inhalation = Taking \ in \ O_2

Exhalation=Giving out CO2Exhalation = Giving \ out \ CO_2

💡Examples

Problem 1:

Which gas do we inhale to help our body produce energy?

Solution:

Oxygen (O2O_2)

Explanation:

During the process of respiration, our lungs take in Oxygen (O2O_2) from the air. This oxygen is then used to break down digested food to release energy.

Problem 2:

Name the organ that connects the mouth to the stomach.

Solution:

The Food Pipe (Esophagus)

Explanation:

The food pipe or esophagus is a tube-like structure that carries the chewed food from the mouth down into the stomach for further digestion.

Problem 3:

What is the waste gas that we breathe out?

Solution:

Carbon Dioxide (CO2CO_2)

Explanation:

When our body produces energy, Carbon Dioxide (CO2CO_2) is created as a waste product. We remove this from our body by exhaling through our nose or mouth.