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.
Arteries (along with smaller arterioles and microscopic capillaries) convey oxygen- and nutrient-rich blood to the body's tissues. In turn, veins bring nutrient-depleted blood back to the heart. Along the way, blood is routed through the kidneys and liver, as well, filtering waste products from the blood.