BLOOD PRESSURE
What is blood pressure?
• Blood Pressure is the
force per unit area on the
wall of a blood vessel
• Measured in terms of
mmHg
• Measured in largest
arteries near the heart
What all plays
a role in
blood
pressure?
Resistance
• Exactly what it sounds
like, the resistance of
blood flow
• Makes blood flow difficult
• Seen well away from the
heart
Viscosity
• Thickness of the blood
• Greater viscosity, harder
to move
• Lower viscosity, the
easier the flow
Total Vessel Length
• The longer the blood
vessel, the more
resistance
• The more resistance, the
higher the blood pressure
• Adding weight adds miles
to your total blood vessel
length
Blood Vessel Diameter
• This is what changes most
often…the other three stay
relatively constant
• Friction – the outside wall
causes friction on blood
passing close to the outside,
slowing it down
• Laminar flow versus turbulent
flow
Hopefully this works
• http://www.voobys.com/video/search_vide
o.php?q=laminar+turbulent+flow
Systemic Blood Pressure
• Systemic blood flow just means that
blood flows through a patter like a
circuit
• It is a circular pattern
• Think back to our picture of the heart.
Where would pressure in the blood flow
pattern be highest? Lowest?
Systolic vs. Diastolic Pressure
• Systolic pressure is the pressure
when the heart is pumping
• Diastolic pressure is the pressure
in the vessels when the heart is
relaxed
• The difference between the two is
called pulse pressure
• Numbers at a Dr.’s office is
systolic over diastolic pressures
Normal Blood Pressure
• A normal blood pressure is 120/80
mmHg
• During the lab tomorrow, we will
be measuring blood pressures of
specific ages of people. We will
label them normal or as having
hypertension
• Hypertension is too much
pressure within your blood
vessels
Return to Sender
• How the blood gets back to the heart
• These structures return blood to the
heart, and are located within the
venous system
• Respiratory Pump – Abdominal
pressure from breathing in squeezes
veins causing a return to the heart
• Muscular Pump – Most important
pump in return of blood. Muscles
surrounding veins contract and relax
“milking” blood back to the heart.