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Circulatory Fluid DynamicsThe Cardiovascular System |
The cardiovascular system consists of two pumps and two
vascular beds. [See Diagram] The two pumps are located side by
side in the heart and work in series.
Each pump
forces blood through a progression of branching tubes that carry
the blood through its designated path. The pulmonary vascular bed
goes through the lungs as oxygen is diffused into the
bloodstream. This oxygenated blood (seen in red) returns to the
heart and the second pump provides the blood with the gusto to
flow through the systemic vascular bed. It is in this process
that the body receives its nutrients, once again, via diffusion.
The blood is then returned to the fisrt pump (seen in blue) and
the process repeates. Besides the replacement of
"tired" blood, the cardiovascular system can be viewed
as a closed system-- which is to say that the fluid is of finite
and constant volume.
The vascular beds serve as the containers for the purpose of guided the flow of the blood. These containers are a progression of branching tubes get smaller (about 70%) at each branching, or bifurcation. These tubes are labeled according to size and function. They range is size from 15 mm to about 0.006 mm and carry blood both too, called veins, and from, arteries, the heart pumps.
The blood consists of "a suspension of particles in a complex aqueous continuous phase." (Fung 1970) Which is to say that it is a water based liquid, called plasma, that is continuous in nature and carries lots of platelets, red cells, white cells, and various organic and inorganic molecules.
Although life is sustained by the various chemicals proteins and cells dissolved or suspended in the blood we will only be concerned with the qualities that effect its flow.
Variable control of the cardiovascular system is achieved roughly by two inter-related factors.
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