Blood Pressure: Effects of Posture on Arterial Blood Pressure

Blood Pressure
First name, Last name
Institution

Introduction
Hydrostatic pressure of blood (fluid) helps in producing the blood flow pressure against the
blood vessels walls (Funamoto, Nam, Kimura et al, 2010). In general for a flow of fluid to be
initiated then it must move from the area where the hydrostatic pressure will be higher to area
where there is a low hydrostatic pressure. In arteries, the area where we expect to have a higher
hydrostatic pressure is the area near the heart, therefore blood will be pumped by the heart and
will flow through the arteries but this will slowed by narrow arterioles openings. During systole,
the walls of the arteries stretch when new blood is allowed to enter the arteries (Levy, Ehret et al,
2009); therefore the stretch helps in accommodating the pressure that is increased by extra blood.
During diastole (Conen, Tedrow et al, 2009, the walls of the arteries return back normal positions
this is due to elastic properties they hold. The blood pressure reading for both systole phase and
diastole phase is shown in figure 1 below. For example if a blood pressure reading is recorded as
130/50 will indicate that during systole the reading will be 130 mm Hg, while during diastole the
reading will be 50 mm Hg. In process of cardiac cycle the arterioles blood is emptied at a
constant flow rate. The blood flow resistance experienced during the cardiac cycle is called
peripheral resistance.

Figure 1: The relationship between blood pressure to blood velocity through the arterioles and
arteries (Brothers, Bhella et al, 2009.
The volume of blood that is pumped at one minute by the heart is called cardiac output (Mayer
and Suttner, 2009). Its calculation entails a multiplication of the number of contraction of heart
which occurs per minute by the stroke volume, which is the pumped blood volume per left
ventricle contraction into the aorta. Therefore an increase in heart rate will increase the cardiac
output; this can be experienced majorly during exercise activities. Furthermore an increase in
stroke volume will similarly increase the cardiac output, this will be experienced when their will
be a greater contraction of the heart with a higher strength. In order to increase the stroke volume
then the speed of the blood circulation must also be increased throughout the body as more blood
will be allowed to enter the heart as it contracts and expands. The blood vessels will relax during
high exertion and in the process it will increase its diameter, moderating the heart rate and
ensures that the muscles are supplied with adequate oxygenated blood. The blood vessels
diameter can be decreased by stress and in the process increasing the blood pressure. The high
blood pressure can also be resulted from signals of nerves, hormones, lying down and also
standing.
Objectives
To determine the posture effect on arterial blood pressure