Blood Pressure
Blood Pressure is the force your blood pushes against the walls of your blood vessels as your heart pumps.
A garden hose lies flat on the ground with no water in it. Turn the tap on and the hose walls bulge as water pushes on them. Turn the tap higher and the walls bulge even more. Blood pressure is the same: your heart pumps blood, and the push on vessel walls is the pressure.
Explaining blood pressure by grade level
Put two fingers on your wrist and feel the beating. That beat is your heart pushing blood through your body. When you run, your heart beats faster and pushes harder. When you sit still, it slows down and pushes less.
Projects that explore blood pressure
Each heartbeat sends the force of blood pushing through every artery as a pressure wave. You can feel this wave at the wrist (radial artery), the neck (carotid artery), and behind the knee. Each pulse point connects to a different artery carrying blood to a specific region of the body.
A blood pressure reading gives two numbers, and each one matches a different phase of the heart's pump cycle. You wrap a cuff around someone's upper arm, inflate it, and then slowly release the air while listening through a stethoscope. The first sound marks the systolic pressure — the force when the heart pumps. When the sounds stop, that reading is the diastolic pressure, the force when the heart rests between beats. What you are hearing are the brief moments when the brachial artery, squeezed shut by the cuff, opens and closes again with each heartbeat as the pressure drops.