Respiratory System worksheets.pdf - Free Printable

Let's solve this worksheet step by step using the words provided in the box:

Words in the box:
- air
- oxygen
- inhale
- exhale
- lungs
- trachea
- respiratory
- bronchi
- carbon dioxide
- diaphragm
- water vapor
- mucus
- nose
- yawn
- cough
- pharynx
- sneeze
- blood

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Passage with blanks and solutions:

> All animals need oxygen to make energy from food. We get this oxygen from the air that we breathe. In order to get this oxygen into the blood where it can be transported to the rest of the body, the air travels through a system of organs called the respiratory system.

✔ Explanation:
- Animals need oxygen for cellular respiration (energy production).
- Oxygen comes from the air we breathe.
- The system responsible is the respiratory system.

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> When you inhale or the yawn, air enters the body through the nose or the mouth. From there it passes through the pharynx, which forces air into the trachea and food into the esophagus. The air travels down the trachea into two branching tubes called bronchi and then on into the lungs.

✔ Explanation:
- Inhale means to breathe in; yawn is also a way air enters.
- Air enters via nose or mouth.
- Then goes through pharynx (throat), which directs air to trachea (windpipe) and food to esophagus.
- Trachea splits into bronchi (plural of bronchus), leading to lungs.

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> In the lungs oxygen from the air enters the blood. At the same time, the waste gas carbon dioxide leaves the blood and then leaves the body when you exhale. Some water vapor also leaves the body when you exhale, which is why mirrors get foggy when you breathe on them. The diaphragm is the muscle that controls the lungs.

✔ Explanation:
- Oxygen diffuses into blood in the alveoli of the lungs.
- Carbon dioxide (waste product) moves from blood into air sacs and is exhaled.
- Water vapor is released during exhalation — causes fogging on mirrors.
- The diaphragm contracts and relaxes to help inhalation and exhalation.

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> It is important to keep the respiratory system clear so oxygen can keep flowing into your body. If something gets in your nose and irritates it, you sneeze. If something gets in your trachea or bronchi and irritates it, you cough. If something irritates your diaphragm, you hiccups. Finally, if the brain thinks you are not getting enough oxygen, then it forces you to inhale.

Wait — “you hiccups” is grammatically incorrect. But the word hiccup is in the box. Let’s check the sentence:

> "If something irritates your diaphragm, you hiccup."

✔ Corrected: You hiccup (not hiccups).

And the last one:
> "...then it forces you to inhale." → Yes, correct.

But let’s recheck the original passage:

> "If something irritates your diaphragm, you ________."
→ The word hiccup fits here. Hiccups are caused by involuntary spasms of the diaphragm.

And:
> "if the brain thinks you are not getting enough oxygen, then it forces you to ________."
→ Inhale makes sense — the brain triggers breathing to increase oxygen intake.

So final answers:

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✔ Final Completed Passage:

All animals need oxygen to make energy from food. We get this oxygen from the air that we breathe. In order to get this oxygen into the blood where it can be transported to the rest of the body, the air travels through a system of organs called the respiratory system.

When you inhale or the yawn, air enters the body through the nose or the mouth. From there it passes through the pharynx, which forces air into the trachea and food into the esophagus. The air travels down the trachea into two branching tubes called bronchi and then on into the lungs.

In the lungs oxygen from the air enters the blood. At the same time, the waste gas carbon dioxide leaves the blood and then leaves the body when you exhale. Some water vapor also leaves the body when you exhale, which is why mirrors get foggy when you breathe on them. The diaphragm is the muscle that controls the lungs.

It is important to keep the respiratory system clear so oxygen can keep flowing into your body. If something gets in your nose and irritates it, you sneeze. If something gets in your trachea or bronchi and irritates it, you cough. If something irritates your diaphragm, you hiccup. Finally, if the brain thinks you are not getting enough oxygen, then it forces you to inhale.

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✔ Summary of Answers (in order):

1. oxygen
2. air
3. respiratory
4. inhale
5. yawn
6. nose
7. mouth
8. pharynx
9. trachea
10. bronchi
11. lungs
12. blood
13. carbon dioxide
14. exhale
15. water vapor
16. diaphragm
17. sneeze
18. cough
19. hiccup
20. inhale

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