It's safe to say we're witnessing life and death on screen. Professor Grodzieński dissects a heart from a trout embryo. Microscopic images reveal the formation of the heart and its contractions. By eliminating individual heart components, we arrive at the contractile center. The effect of temperature on heart rate is profound. An increase in temperature is accompanied by increasingly rapid heart contractions. The heart pumps blood into blood vessels, their smallest branches reaching every corner of the body. We trace the movement of blood cells within the vessels. When the temperature exceeds 25°C, the heart stops.
