Skip to main content
Mon Prof Augmenté
Download
Download

Language

Running Heart and Lungs

Age 15 · Biology

The picture opens with a subscription

When you run, your leg muscles burn through oxygen and fuel much faster than when you sit still. Your heart beats faster and your breaths get deeper so blood can carry the extra oxygen to those muscles.

This picture is part of the full library

Every lesson is open to everyone for 7 days after it is published. This one came out on September 9, 2026: its text stays readable here, and its picture opens with a subscription.

See the plans

The app is free. A subscription opens every lesson, in every school year.

Age 15: open this week

Browse Age 15

In the picture

  1. The heart inside the chest cutaway
  2. The lung behind and above the heart in the same cutaway
  3. The bundle of thigh muscle fibres inside the leg cutaway
  4. The thick blood vessel arcing across the hip from chest to thigh

Examples

  • Climbing four flights of stairs leaves you panting and able to feel your pulse in your neck.
  • A footballer’s chest heaves after a sprint, then slowly settles during a break in play.

Key takeaways

  • Working muscles need more oxygen, so heart rate and breathing rate both rise.
  • Deeper breaths load more oxygen into the blood, and a faster heart delivers it sooner.

Quiz: Running Heart and Lungs (Age 15)

  1. During a hard run, why does your heart beat faster?

    • Working muscles need oxygen delivered more quickly, and blood is what carries it
    • The moving muscles push extra blood back into the heart, forcing it to beat faster
    • Running heats the body, and hot blood has to be pumped to the skin to cool down

  2. What does breathing more deeply during exercise mainly achieve?

    • It stretches the lungs so they can store oxygen for later use
    • It loads more oxygen into the blood with every breath
    • It slows the heart so blood spends longer inside the lungs

  3. Why are the leg muscles the main reason your heart and breathing change while you run?

    • They are the biggest muscles, so they hold the most blood while you rest
    • They are the furthest from the heart, so blood reaches them slowly
    • They are contracting over and over, burning fuel and oxygen far faster than at rest

The answers, each with its explanation, are in the app. This lesson has left the free week, so its quiz is part of the subscription.

Get the app

Free app, optional subscription
App Store Google Play

Carry on in the app

At least one new illustrated lesson every weekday for your child’s year, with its quiz and a reminder at 6:15 pm.

Your child’s teacher does not use My Enhanced Teacher yet?

Tell them about it

More lessons, Age 15

Share this lesson

Biology, Age 15