Q: "Why does my heart beat?" ~ Alex, 5, Sherman Oaks, CA.

Here is the answer from Dr. Joel Kirsh, Staff Cardiologist and Project Investigator in Cardiology at The Hospital for Sick Children.

A: "The heart, like other organs in your body, is made up of millions of cells, tiny individual machines that are too small to see without a microscope. Cells have unique jobs depending on where in your body they are working. Most of the heart's cells have two jobs – job one is as a pump, squeezing during your heartbeat so that blood is pumped from your heart out to your lungs and body and job two is like a telephone, sending an electrical signal to the next cell down the line so that heart cells all squeeze at about the same time. In a few areas of the heart, special cells known as "pacemaker cells" don't wait for a telephone call from their neighbour, they start the electrical signal off on their own, at a speed that depends on whether you are sleeping, sitting, walking or running. Your heart beats almost a million times a week"

The scientists at SickKids are experts in most areas of health and life science. They spend their days asking tough questions and searching out the answers. Now it is your turn to ask them the tough questions.

Have you ever had a burning question about your body or about your health and didn’t know how to find the answer? This might just be the opportunity to get to the bottom of it!

You have the chance to submit your question and it will be answered by a scientist who specializes in that area. The best questions and answers will be featured on the Research Institute website: http://www.sickkids.ca/research.

Check the website often to see if your question gets posted. You can learn about what others want to know and if you read enough answers, you may even become a health expert yourself!