Bill Nye The Science Guy 4 16 -1 -1 251071 0.0 0.0 0 Your heart pumps your blood around your body, all hours, every day of the week, to keep you alive. Your heart is about the size of your fist, and it’s made of special muscle called “cardiac” (KAR-dee-ak) muscle. Cardiac muscle lets your heart keep the beat, it can also speed up or slow down, depending on what your body needs. Your heart works like an automatic pump – it squeezes, or contracts, and un-squeezes, or relaxes, to push blood through the four different sections of your heart. Valves, special one-way openings, are like little doors between the sections – making sure your blood moves in only one direction through your heart, to your lungs, back to your heart, and then around your body again. 26 http://image.tmdb.org/t/p/original/d5vCggoMSmWGd7bLUTgeSoBvXdJ.jpg 1996-02-14 1996-02-14 false Rabbit Ears Productions Public Broadcasting Service KCTS Television James McKenna Bill Nye Michael Gross Kit Boss Erren Gottlieb Ian G. Saunders Adam Gross Seth Gross Simon Griffith Scott Schaefer Darrel Suto Michael Palleschi Lynn Brunelle Toby Lawless Family Magician https://www.themoviedb.org/person/1234124 2020-08-23 13:00:58 UNKNOWN BNTSG S04E16 Heart.avi