Systole facts for kids
Systole (say "SIS-toh-lee") is the part of your heartbeat when your heart muscle squeezes. It happens right after diastole, which is when your heart fills up with blood. During systole, the two main pumping parts of your heart, called the ventricles, contract or squeeze.
The ventricles are the biggest parts of your heart. They work to pump blood out to your whole body and to your lungs. When your heart muscle gets an automatic electrical signal, it tells the heart to squeeze. This squeeze pushes blood out of your heart and into your body.
How Your Heart Pumps Blood
Your heart has four main sections, like rooms in a house. Above the ventricles are two smaller rooms called atria. The atria squeeze first, during the last part of diastole. They send blood down into the bigger ventricles below them.
After the atria push blood into the ventricles, special doors called valves close. This stops blood from flowing backward into the atria. Once the ventricles are full and their valves are closed, they get their turn to squeeze. So, the atria and ventricles squeeze one after the other.
The right ventricle pumps blood to your lungs to pick up oxygen. The left ventricle pumps this oxygen-rich blood to the rest of your body. This amazing pumping action is why you can feel your pulse!
What is Systolic Pressure?
When your heart muscle squeezes during systole, it creates the highest pressure inside your arteries. This is called "systolic pressure." It's the strongest push of blood against the walls of your arteries.
The lowest pressure in your arteries happens when your heart muscle relaxes and fills with blood. This is called "diastolic pressure."
When doctors measure your blood pressure, they give you two numbers. The first number is always the systolic pressure. For example, if your blood pressure is 120/80, the 120 is your systolic pressure. The 80 is your diastolic pressure.
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