16
.
Dynamics
of
the
Vascular
System
There are four heart valves involved in the filling and pumping action
of
the heart. The mitral valve situates between the left atrium and the left
ventricle. It controls the flow between these
two
chambers, but is a one-
way valve. The tricuspid valve as the name implies has three cusps.
These are the posterior, the septal, and the anterior. The cusps have
similar geometric shapes. The right ventricle and the low-pressure
pulmonary arterial system
on
the other hand,
is separated by the
pulmonary valve. The aortic valve separates the left ventricle from the
ascending aorta leading to the high pressure systemic arterial system.
These valves are tricuspid valves whose leaflets are
of
similar shape.
PRESSURE
Mean
pressure-
20%
5%
75%
BLOOD
VOLUME
8
Fig.
2.1.2:
Blood pressure and blood volume distribution
of
the systemic circulation.
Notice the largest pressure
drop
occurs in the arterioles and the largest amount
of
blood
volume reside in the veins which serve as reservoirs. From Rushmer
(1972).
