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Red Blood Cells, Oxygen, and Your Body

This month we're traveling all over your body! Because that's where your oxygen is needed.

Your red blood cells are filled with a protein called hemoglobin. The hemoglobin has iron in it, which is what lets it carry oxygen. Your blood travels all over your body to deliver that oxygen.


To see all lessons currently available, go to the Classroom (for current students) or the All Lessons page (future students).


See Where the Blood Goes

Your capillaries (tiny blood vessels) are everywhere. Just like you can't get a package delivered from a truck that's in the middle of a busy highway, your blood can't deliver oxygen until it gets off the "highway" (arteries) and travels through "quiet neighborhood streets" (capillaries). You can see this all over your body with capillary refill.

  • Press on your lip with your finger while watching in a mirror or watching each other. Watch how it turns pale when you press the blood out of the capillaries and then quickly turns red again when you let go and the blood comes back into the capillaries.

  • Gently pinch a fingertip between your thumb and forefinger, pressing down on the nail. Watch how it turns pale and then colors again.

  • Where else can you see this? Try toenails. Try your skin on other parts of your body. Does it work on the bottoms of your feet? On your arms? What about your ears?

Feel Where Your Blood Goes

  • You can feel a pulse in many parts of the body. Most kids can find their carotid pulse. Have them place their index and third fingers on their neck to the side of your windpipe just under the chin. Remind them that they are feeling their blood going up to their brain, eyes, etc.

  • Once they've found their carotid pulse, you can help them find their radial pulse. They will place two fingers between the bone and the tendon over their radial artery, which is located on the thumb side of your wrist. They are feeling the blood going out to their hands and fingers...it will go out to the capillaries under their fingernails.


Try Struggling to Breathe


No one should do this who has a lung or heart condition (including asthma).

  • Give each kid two drinking straws...a regular straw and a boba straw (also known as a milkshake straw). They can try breathing through each straw. Most kids will say it's easy/no big deal.

  • Now have them run in place or do jumping jacks to get them breathing more heavily. Then try breathing through the smaller diameter straw. Now they'll feel how hard it can be to breathe! Have them try the larger diameter straw. And then let them take big deep breaths like normal. When someone has pneumonia, COPD, uncontrolled asthma, or other lung conditions, it's common to be able to breathe reasonably well while sitting quietly but then struggle when walking up stairs or otherwise exerting themselves.

If you have any questions about this month's lessons, let us know! Maybe they'll become a Quick Question or a whole new lesson!