Heart depending on what is counted as a chamber. The atrium and ventricle are sometimes considered "true chambers", while the others are considered "accessory chambers". Primitive fish have a four-chambered heart, but the chambers are arranged sequentially so that this primitive heart is quite unlike the four-chambered hearts of mammals and birds. The first chamber is the sinus venosus, which collects deoxygenated blood from the body through the hepatic and cardinal veins. From here, blood flows into the atrium and then to the powerful muscular ventricle where the main pumping action will take place. The fourth and final chamber is the
Arabella (given name) Arabella (given name) Arabella is a female given name of Scottish origin. The earliest known namesake: Arabella de Leuchars (c.1135-1203): was a granddaughter of the Scottish king William the Lion; the earliest English namesake was the granddaughter of Arabella de Leuchars: Arabella de Quincy (c.1186-1258), the daughter of Saer de Quincy, 1st Earl of Winchester. Typically of medieval bearers of the name both these Arabellas are also documented as Orabel[la] and Orabilia, and in documents which Latinize names as Orabilis. A Latin construction which suffixes "orare" with "ābilis" - thus interpretable as "given to prayer" or "entreatable" - Orabilis has