Voyage on the Red River

The year was 2140. Tryphonia was the youngest pilot ever chosen for the S.S. Corpuscle, a submarine shrunk (made tiny) smaller than a grain of salt. Her mission (special job): sail the secret Red River that flows inside every human body. Her teacher, Grace, spoke through the radio. “Remember, Tryphonia, you are travelling the circulatory system (the body’s blood-transport network). Report everything you see.”

The Corpuscle was injected (pushed in with a needle) into a patient’s arm. At once, Tryphonia was swept along a wide tunnel. “I’m in a blood vessel (a tube that carries blood),” she radioed. “The walls are alive! And the river is packed with red discs.”

“Those are red blood cells,” said Grace. “Their job is to carry oxygen (the gas we breathe in to stay alive). Follow them, they will lead you to the great pump.”

Tryphonia raced along, past soldier-like white blood cells that hunted germs (tiny things that cause illness), and past tiny platelets (cells that plug leaks). Then she heard it: a mighty (very powerful), steady sound. Lub-DUB… lub-DUB… lub-DUB.

Ahead loomed (appeared, large and close) a huge muscular (made of strong muscle) chamber, squeezing like a fist. “The heart!” Tryphonia gasped. “It’s the pump! Every squeeze pushes the blood on its journey.” The heart flung the Corpuscle out through a thick, strong tunnel. “The blood is bright red here.”

“You are in an artery,” Grace explained. “Arteries carry bright red, oxygen-rich (full of oxygen) blood AWAY from the heart.”

The river split into streams so thin the cells passed in single file (one behind another). “A capillary,” Tryphonia whispered. Here the red cells handed their oxygen to the body’s tissues (groups of body cells) and picked up waste gas, carbon dioxide (the gas we breathe out). The blood turned a dull, dark red.

The current (moving water) carried her back through wider tunnels called veins, returning the tired, dark blood to the heart. From there it was pumped to the lungs (the organs we breathe with), swapped its carbon dioxide for fresh oxygen, bright red once more, and began the whole loop again.

Tryphonia wrote in her log: The heart never rests. Arteries carry oxygen out, veins bring waste back, capillaries do the swap, and the lungs recharge the blood. One perfect loop, beating every second of our lives.