🔹 Control of Breathing – Who Tells Us When to Breathe?

Our breathing is not random. It is controlled automatically by a special part of our brain.

🧠 Medulla Oblongata – The Breathing Center

• It is a part of the brainstem.
• Contains the respiratory center, a group of nerve cells (neurons).

✅ What does it do?

1. Detects carbon dioxide level in the blood.
   • When CO₂ increases, it sends signals to the diaphragm and intercostal muscles to contract.
   • This causes inhalation.
2. Stops sending signals after a short time.
   • The muscles relax, and exhalation happens.
3. This cycle continues automatically.
   • You don’t have to think about breathing — your brain does it for you!

🧠 Example:
Like an automatic fan that turns on when the room is hot and turns off when it’s cool — your medulla does this with your breathing!

🧠 Recap: The Complete Breathing Mechanism

Phase	Muscles	Chest Volume	Lung Pressure	Air Movement
Inhalation	Contracts	Increases	Less than outside air	Air flows in
Exhalation	Relaxes	Decreases	More than outside air	Air flows out

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💡 Bonus: When Do You Use Forceful Breathing?

Sometimes, we need to forcefully exhale, like:

• Blowing up a balloon
• Sneezing
• Coughing
• Exercising hard

In such cases, internal intercostal muscles and abdominal muscles also help in forceful expiration.

✅ Summary in Simple Words

• Breathing is how air moves in and out of the lungs.
• Inhalation: Chest expands, air pressure drops, air enters.
• Exhalation: Chest contracts, pressure rises, air is pushed out.
• Controlled by the brain (medulla oblongata).
• Muscles involved: Diaphragm and intercostal muscles.