Download Blood Pressure

Blood Pressure
blood pressure is the pressure blood on the walls of the
circulatory system.
Blood pressure depends on two factors…
1. cardiac output - any increase in the amount of blood pumped from the
heart each minute will increase blood pressure
- loss of blood decreases blood pressure.
2. arteriolar resistance –
- if the diameter of the artery or arteriole is reduced, less
blood can flow through – therefore blood pressure
increases.
- arteriolar dilation increases blood flow from the arterioles
reducing blood pressure.
Other Factors Affecting Blood Pressure
Heart Rate:
* faster heart rate, results in greater pressure on the blood
vessels
Cholesterol and Fat Deposits:
* decreases the inside diameter of the vessels, more
resistance occurs, resulting in increased pressure. This is
referred to as atherosclerosis
Viscosity of the Blood:
* thick blood flows less readily
* viscosity depends on the number of RBCs compared to
the plasma
Hypertension
Blood pressures consistently above the normal levels result in
a condition called hypertension, commonly known as high
blood pressure.
Hypertension is dangerous because it forces the heart to work
harder to pump blood around the body.
Often there are no symptoms until a serious event, such as a
heart attack or stroke occurs.
Blood pressure is measured with an instrument called a
sphygmomanometer.
Blood pressure is measured as systolic pressure over
diastolic pressure.
Normal blood pressure for teenagers is approximately
120/80.
The units for blood pressure are mm Hg (millimetres of
mercury)