Also see user session. In telecommunication, a session is a series of interactions between two communication end points that occur during the span of a single connection.
The path of blood through the heart begins with the right atrium receiving blood, which has circulated through most of the body. This blood is relatively low in oxygen because most of it has already been delivered to different organs and tissues.
Blood is circulated around the body through blood vessels by the pumping action of the heart. In animals with lungs, arterial blood carries oxygen from inhaled air to the tissues of the body, and venous blood carries carbon dioxide, a waste product of metabolism produced by cells, from the tissues to the lungs to be exhaled.