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
Brendan (given name) There is no etymological link between "Brendan" and "Brenda". This feminine given name, pronounced , is thought to be derived from the Old Norse element "brand", meaning "(flaming) sword". In most cases, the masculine given name "Brandon", pronounced , is considered to be derived from the surname "Brandon", which is in turn derived from two Old English elements. In some cases, the masculine given name "Brennan" may be used as a contracted form of "Brendan". Brennan is etymologically unrelated to "Brendan". It is derived from the surname "Brennan", which is an Anglicised form of the Irish "Ó Braonáin". The popularity