Atrium (heart) similar function. Some animals (amphibians and reptiles) have a three-chambered heart, in which the blood from each atrium is mixed in the single ventricle before being pumped to the aorta. In these animals, the left atrium still serves the purpose of collecting blood from the pulmonary veins. In some fish, the circulatory system is very simple: a two-chambered heart including one atrium and one ventricle. Among sharks, the heart consists of four chambers arranged serially (and therefore called a serial heart): blood flows into the most posterior chamber, the sinus venosus, and then to the atrium which moves it to
Hayden (given name) but down from No. 52 in 2012 and No. 43 in 2011. Hayden (given name) Hayden is a given name in the English language. The name is variant of the given name "Haydn", which is derived from the surname "Haydn" in honour of composer Joseph Haydn (1732–1809). The surname "Haydn" originated as a respelling of the nickname "Heiden", meaning "". The name is derived from the Middle High German "heiden", and from the Old High German "heidano". The form "Haydn" was generally considered a masculine given name up until the mid 20th century. The popularity of "Hayden" has been influenced