Science For Kids: A HEARTY Lesson

Science Talk! A Heart-y Lesson   Many opportunities arise to teach young children about their heart! A simple clenching of a little fist can serve as a first lesson. Tell your child that their heart is an upside-down pear about the size of that fist and that an adult's  bigger fist measures up to the size of a grown-up heart. If your child asks what exactly the heart is, start by letting them listen to your heartbeat. By holding an ear to the center of your chest - or, optimally, a little to the left-of-center - they will hear the 'boom, boom' sound that we are all so familiar with. That 'boom, boom' should be heard about 70-80 times per minute.   If you entertain your child by running on the spot for about 20 seconds, you can demonstrate to them that the rate increases with exercise. A functioning toy stethoscope, available in many toy stores, will refine the 'boom, boom' sound into a 'lub, dub, lub, dub'. Let's review how this sound is made. The heart is divided into four rooms, or chambers. The left and right atria are located on the top 'floor' and left and right ventricles are located on the bottom 'floor'. Doors, called valves, can be found between the atrium and the ventricle of each side of the heart - that is, going from the top floor to the bottom floor. Doors can also be found going from the ventricles to the major blood vessels - or, going out from the bottom floor.   The left side of the heart is used to pump oxygen-rich blood out to the body. The oxygen, which is taken from the lungs, comes from the air we breathe in. Oxygen-rich blood is brought to the left atrium. The valve between the left atrium and the left ventricle opens to let the blood flow down into the ventricle. When the left ventricle is filled, the valve between the two closes to prevent backwash of the blood. The left ventricle then produces a mighty contraction - the 'lub' sound - to push the blood out of the heart. Immediately, the valve from the left ventricle out to the aorta - the big blood vessel which carries blood to the tissues - opens and the blood actually begins its journey. This last valve from the heart then shuts again - the 'dub' sound - to prevent flow of blood back into the heart. When the blood comes back to the heart, it no longer has any oxygen in it. This oxygen-depleted blood enters the right ventricle, gets pushed through the valve leading to the right atrium and is, then, pumped into the lungs where it will be restocked with oxygen. This will start the whole process over again. A very efficient machine, the heart will pump from early in our development, in the womb, until the last moment of life. If you want to impress your kids with really high numbers - which they always love - let them know that their heart will beat about 30 million times in a year and that blood travels through about 60,000 miles of blood vessels in a grown-up's body! (Wow, cool!) So, the next time your child clenches a fist to lash out at an unsuspecting sibling, stop them cold with the story of how that fist is like the heart. Although it seems as though there is a lot of information and terminology, you'll be surprised at how heart-y your child's appetite will be for knowledge about that 'boom-boom' sound going on in their chest. You are free to use this article, in whole or in part, as long as you include the complete contribution, including a live web site link.  Also, please send and email notifying me (Elva O'Sullivan at elva@sciencewithme.com) where and when the material will appear. Thanks. Visit our website : www.sciencewithme.com © 2003 -2006 Science With Me® LLC. All rights reserved.