heartbeat, n.All

With every heartbeat, a man's testicles produce about 1,500 sperm.

Women's hearts typically beat faster than men's hearts.

Couples in love can synchronize their heartbeats by simply gazing into each others eyes.

A blue whale's heart only beats about twice per minute

Leonardo studied the flow of blood through the valves of the heart, by creating a mold of a real heart with wax and then pumping water mixed with seeds through a glass caste of it.