🌬️ HUMAN RESPIRATORY SYSTEM

🔹 Introduction

In your previous classes, you learned how food gives us energy. But how does this energy come out of food?

Imagine you eat a banana. The body breaks it down into smaller parts like glucose. Now, just having glucose is not enough — we need to “burn” it inside our cells to get energy. But this burning is not like fire — it’s a slow and controlled process called cellular respiration.

This process needs oxygen and gives out carbon dioxide. Oxygen is taken in from the air, and carbon dioxide — a waste gas — is sent out of the body.

🔹 What is External Respiration?

External respiration means the movement of gases in and out of the body.

Definition:

“External respiration is the process by which oxygen is taken from the environment into the body, and carbon dioxide is removed from the body into the environment.”

🔄 It includes:

• Breathing in (Inhalation) – taking oxygen
• Breathing out (Exhalation) – releasing carbon dioxide

🧠 Think of this like opening a window in a room:

• Fresh air (oxygen) comes in.
• Stale air (carbon dioxide) goes out.

🔹 Organs Involved in Respiration

All the organs that help in breathing and exchanging gases make up the Respiratory System.