Figure 8.7: The internal structure of the mammalian heart.In the previous sections we have discussed pulmonary and systemic circulation, and we have
described the four chamber structure of the heart as well as some of the major arteries and
veins that transport blood towards and away from the heart. In order to summarise all this
information, study the flow diagram below which describes the passage of deoxygenated
blood through one full cycle.228 8.2. Circulatory systems in animals