In order to summarize how blood flows in the body, let's take a trip through the
body's circulatory system (see figure 3-3). We will enter the system at the inferior vena
Direction of blood flow
Superior vena cava
Inferior vena cava
Figure 3-3. Blood flow to and from the heart. (Not drawn to scale; front view).
a. Vena Cava. There are two major blood veins that empty into the right atrium.
The inferior vena cava carries oxygen-poor blood from the lower trunk and legs. The
superior vena cava drains blood from the head and upper chest.