Circulatory System
Circulatory System is your body's network of heart, blood, and blood vessels that moves food and air to every cell.
A kitchen has a pump that pushes water through pipes to every sink. The main pipe splits into smaller ones that reach each tap. Used water drains back through a return line to the pump. Your heart works the same way: it pumps blood out through arteries and pulls it back through veins.
Explaining circulatory system by grade level
Your heart beats all day and all night. Each beat pushes blood through tubes in your body. The blood brings food and air to every part of you. You can hear your own heart with a paper tube held to your chest.
Projects that explore circulatory system
Your heart pumps blood all day long. You can hear it beat through a tube. It beats faster after you run.
The circulatory system moves blood to every part of your body through arteries. You can feel this blood flow as a pulse at the wrist (radial artery), neck (carotid artery), and inner thigh (femoral artery). A stethoscope helps you match the pulse to the heart sounds.
Resting heart rate differs from person to person, and gender may be one reason why. To find out, you take the brachial pulse — the pulse at the inner arm — of 25 males and 25 females. Each person sits quietly for three minutes, then you count their pulse three times at one-minute intervals and average the results. The females in one study averaged 85 beats per minute; the males averaged 79. That six-beat gap suggests gender affects how fast the heart moves blood at rest.
With each heartbeat, the circulatory system pushes blood through the vessels with measurable force. A sphygmomanometer — the cuff wrapped around your upper arm — captures that force in two readings. As you slowly release the cuff's pressure, the first sound through the stethoscope marks the systolic pressure, when the heart pumps. When the sounds stop, that quieter number is the diastolic pressure, when the heart rests. Measuring different groups of people reveals how much those two readings vary from one person to the next.
Your heart speeds up during exercise to move blood faster. Outside sounds can change this rate even more. Music raised the heart rate above what stair climbing alone did.