Breathing in the Body

Contributor: Hannah Brooks. Lesson ID: 12710

Did you ever stop and take a deep breath, or pant after exercising? Why does that happen? And, what comes out of your nose when you exhale? Learn how this breathing process works, without your input!


Life Science

learning style
Kinesthetic, Visual
personality style
Grade Level
Middle School (6-8), High School (9-12)
Lesson Type
Dig Deeper

Lesson Plan - Get It!

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You don't pay much attention to your breathing (except in smog or when it stops!), but there is a lot going on behind the scenes. Actually, behind your ribs!

In the previous Related Lesson in this Respiratory System series, found in the right-hand sidebar, you learned about the basic structure of the respiratory system.

This organ system operates to ensure that you are breathing and distributing oxygen to all the parts of your body. The process of breathing starts when you inhale air through your nose or mouth.


The moisture in your nose and mouth adds water vapor to the air, making it easier to move through the respiratory system. Water vapor adds moisture that allows the air to flow over tissues easily. Think about how lubricants help your bicycle chain move easier — it is the same with moisture in air! Air travels down through the trachea to the lungs.


At the entrance of the lungs, air moves through two large bronchial tubes that branch to the left and the right lung. These two large bronchi branch into many smaller tubes and networks called "bronchioles." Bronchioles end with tiny air sacs called "alveoli," wrapped in small capillary networks responsible for providing the blood supply.


The alveoli play a very important part in the respiratory system because this is where gas exchange occurs. Oxygen is removed from the air taken in by the nose or mouth and dissolved into the blood, and carbon dioxide is transported from blood to the air that will be released on exhale.

The oxygenated blood is then sent to the heart, where it will be pumped throughout the body!

gas exchange process

The breathing process involves inhaling and exhaling air. While the respiratory system is responsible for pulling oxygen out of the air, it relies on other body systems to aid in the actual process of breathing. The muscular system assists the respiratory system by contracting muscles during inhale and exhale.

Take a deep breath.

  • Where did you feel muscle movement?
  • Maybe right above your abdomen?

When you inhale a volume of air, muscles in your chest contract and expand the ribcage. This movement allows for the addition of air! Your diaphragm, a muscle located directly below your lungs, contracts, which increases the space in the ribcage. You may be able to feel your diaphragm contract on really deep breaths!

diaphragm diagram

When you exhale, the opposite muscle movements occur. The diaphragm and chest muscles relax, decreasing the space in the chest and forcing air out.

The act of exhaling removes carbon dioxide waste from the body, aiding the excretion of waste!

You breath around 16 times each minute! That is a lot of muscle contraction and relaxation. The respiratory system is constantly converting air into usable oxygen gas while excreting carbon dioxide. This process allows you to grow and function. It provides your muscles and tissues with blood so they can help you walk, run, and play. The respiratory system ensures that oxygen is passed into your blood so it can pass through vessels throughout your body.

  • How might the respiratory system aid your muscles during exercise?

Discuss this question with a parent or teacher.

In the Got It? section, you will track breath as it moves through the entire respiratory system.

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