Interpretation
The upper, or 
systolic, pressure sound is produced at the
point when blood under pressure in the aorta first passes the
brachial artery obstruction produced by the bladder of the cuff.
The diastolic pressure is the pressure remaining in the vessel
when the heart is at rest between beats and the pressure on the
vessel has been relieved. The 
diastolic pressure is more stable
since it usually reflects vessel wall tension and health, while
the systolic pressure fluctuates more due to changes in cardiac
output. The ideal blood pressure is generally considered to be
120/80. Over age 35, the systolic pressure may be as high as
140-160 A slight rise in the diastolic pressure is common.
The 
pulse
pressure is the difference between the systolic
and diastolic pressures. Thus, at a pressure of 120/80 the pulse
pressure would be 40 mm of mercury. As blood pressure increases,
the systolic pressure elevates faster than diastolic, causing an
increase in the pulse pressure.
Systolic, diastolic and pulse pressures are produced by the
action of blood as it leaves the aorta at a given pressure
following systole. This 
pressure wave distends the muscular
arterial walls which in turn help sustain the pressure to move
blood through the arterioles and capillaries. The pressure in the
vessels dissipates with the widespread branching from the aorta
to the arteries, arterioles and capillaries. However, a pulse may
be detected in major arteries distant from the heart. When a
sphygmomanometer is applied and the brachial artery is completely
occluded, the first sound heard upon deflation is the result of
the left ventricular force (pressure) sending blood 
past the
partial occlusion, hence the loud sound. During diastole no
blood
leaves the heart and pressure is maintained in the arterial
system by the elasticity, width and resistance of the arterial
tree and the organs it serves. Thus, the point at which the
deflating blood pressure cuff no longer even partially occludes
the vessel (the point at which the sounds disappear) represents
the resting or diastolic pressure of the circulatory system.
systolic, pressure sound is produced at the
point when blood under pressure in the aorta first passes the
brachial artery obstruction produced by the bladder of the cuff.
The diastolic pressure is the pressure remaining in the vessel
when the heart is at rest between beats and the pressure on the
vessel has been relieved. The 
diastolic pressure is more stable
since it usually reflects vessel wall tension and health, while
the systolic pressure fluctuates more due to changes in cardiac
output. The ideal blood pressure is generally considered to be
120/80. Over age 35, the systolic pressure may be as high as
140-160 A slight rise in the diastolic pressure is common.
pulse
pressure
pressure wave
past the
partial occlusion