# KINESIOL 1YY3 Lecture Notes - Lecture 9: Mean Arterial Pressure, Brachial Artery, Blood Vessel

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2 Feb 2016
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Pressure throughout the whole system is called the driving pressure or the mean arterial
pressure - NOT THE AVERAGE! - closer to the diastolic pressure
Flow AKA Cardiac Output - L/min of blood out of the heart
Resistance - anything that can slow down the flow of the blood
Increase resistance = increase pressure
Resistance is proportional to …
If we increase viscosity (thickness) = increase in resistance
This only happens if we're growing in size
We can slightly alter the length by opening and closing capillary beds
Vasculature doesn't really change the length of the tube
Any small changes of the size of the lumen (hole where the blood flows) will have a dramatic
change because it's to the power of 4
Diameter / radius of the vessel
Main way of changing the resistance is due to changing the diameter/radius of the vessel
As you move towards the walls of the vessels the cells will move slower and slower
You can't hear it outside of the body because it's so smooth
Laminar flow - straight blood vessel and the blood moves very easily through the vessel
When your blood vessels branch you have a little bit of turbulent flow but not a lot
Overtime can cause more damage to the area
Turbulent flow
Blood pressure cuff - attached to a dial that gives reading in pressure in mm/Hg
(millimeters/mercury)
Brachial artery - tends to be the one that goes through the bend in our elbow - this is
where you would put your stethoscope
Pump up the pressure of the cuff that it blocks the vessel
Blood only squeezes through in the systolic phase - pressure is a bit higher than the
outside
Pressure goes through in a turbulent flow manner therefore you can hear it
Cuff = pressure inside of the vessel - first sound - Korotkuff sound
When sounds disappears - during diastolic phase - no squishing of blood vessel - now it is
laminar flow - smooth flow - no sound
Increase diastolic pressure - higher pressure when it is relaxed - maybe at increased risk
for a cardiac event (stroke, attack etc.)
Typically very high in pressure
First artery leading the heart we have a small cross-sectional area
Increase cross-sectional area
Slows the blood
As we move through we get more and more branches
Lecture 9 Blood Vessels and Circulation
January 25, 2016
1:30 PM
Kinesiology 2YY3 Page 1
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