Simon Pegg is a producer and an actor.
The atrium -LRB- plural  : atria -RRB- is a blood collection chamber of the heart .. blood. blood. heart. heart. It was previously called the auricle , and that term is still used to describe this chamber in , for example , the Mollusca , but in humans that name is now used for an appendage of the atrium .. Mollusca. Mollusca. The atrium is an upper chamber in which blood enters the heart , as opposed to the lower ventricle , where it is pushed out of the organ .. blood. blood. heart. heart. ventricle. Ventricle ( heart ). It has a thin-walled structure that allows blood to return to the heart .. blood. blood. heart. heart. All animals with a closed circulatory system include at least one atrium  /  auricle -LRB- humans have two atria -RRB- .. closed circulatory system. closed circulatory system. The atrium receives blood as it returns to the heart to complete a circulating cycle , whereas the ventricle pumps blood out of the heart to start a new cycle .. blood. blood. heart. heart. ventricle. Ventricle ( heart )