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25 Cards in this Set

  • Front
  • Back
What is the most important pressure in the pressure gradient (usually has amean of 70 to 100 mmHg)?
Arterial pressure
What is an apprxoimate range of mean arterial pressures?
70-100 mmHg
What is an approximate range of mean venous pressures?
0-10 mmHg
What determines blood flow?
Pressure difference
Give an equation for pressure different.
Change in pressure = Blood flow x resistance (or Ohm's version V = IR)
Describe the relationship between vessel radius and flow rate.
It increases by the fourth power
Describe the relationship between vessel length and flow rate.
Flow rate is inversely related to vessel length
List the four assumptions of the Poiseuille's equation.
1. laminar flow 2. flow is through a smooth, cylindrical, rigid tube 3. steady, constant flow 4. Constant viscosity (or blood is a newtonian fuid)
Which is more important in determing flow rate, pressure difference or absolute pressure?
Pressure difference
What is the effect on turbulence on efficiency and cardiac work?
Turbulence is inefficient and makes the heart work harder
What physical property of blood affects viscosity (hint: you can measure this)?
When resistances are arranged in series total resistance is the ______ of individual resistances.
What are the two components of blood which contribute to its overall viscosity?
plasma viscosity and cell viscosity.
What is the approximate value of blood viscosity when compared with water's arbitrary value of 1?
Define: velocity profile is smooth and parabolic, and flow velocities are in the direction of net flow.
Laminar flow
Define: flow in which fluid components do not all move along the net axis of flow.
Where does laminar flow occur in the cardiovascular system?
It occurs in most of the cardiovascular system of healthy individuals
Where does turbulence occur in a normal healthy individual?
Around the aortic valve; this is primarily due to the velocity of the flow around the aorta being high.
What are the three major components of vascular resistance?
Viscosity, radius (to the fourth power), and vessel length
Where are vascular circuits arranged in series found (2)?
GI and kidney
True/False: most of the cardiovascular system is a parallel arrangement of resistances.
How are parallel resistance elements summed?
The reciprocal of each resistance is added and then this sum = 1/total resistance
Define: systolic pressure - diastolic pressure
Pulse pressure
How do changes in vascular resistance affect pulse pressure?
Increases in vascular pressure will decrease pulse pressure assuming all others variables stay the same (this is due to a rise in diastolic pressure)
How do changes in heart rate affect pulse pressure?
With an increase in heart rate, more blood per time will be ejected (assuming adequate filling) resulting in an increase in pulse pressure.