Chapter 18 Flashcards
(56 cards)
What is hemodynamics
the study of blood flowing through the circulatory system
what is flow?
volume of blood at a particular time
What is pulsatile flow? Is it venous or arterial?
when the blood flow varies with cardiac contraction. Because of this, it is arterial flow.
What is phasic flow? Is it venous or arterial?
The blood flow varies with respiration and therefore appears with venous flow.
What is steady flow? Is it venous or arterial?
Fluid moves at a consistant velocity. This is possible with venous flow when a patient temporarily stops breathing.
What is laminar flow
Laminar flow is found when different layers of fluid travel at individual speeds.
Describe the two forms of laminar flow?
Plug: when all the layers travel at the same velocity
Parabolic: when the velocity is greatest in the middle layer and decreases as it goes to the edge.
What does the Reynold’s number predict?
whether the flow is laminar or turbulent.
What is the Reynold’s number for laminar flow?
less than 1,500
What is the Reynold’s number for turbulent flow?
Greater than 2,000
What is the sound assciated with turbulence?
murmur or bruit
What is the tissue vibration or palpable murmur associated with turbulence?
a thrill
What is an eddy current?
another term for turbulence or vortex
What is an energy gradient?
When the blood moves from regions of high to lower energy
What provides energy to circulate blood?
Contraction of the heart
What forms of energy are associated with blood?
kinetic, pressure, and gravitational
What determines kinetic energy? What kinds of objects have more kinetic energy?
an object’s mass and speed. Heavy and quickly moving objects have the most energy.
What is pressure energy?
A form of stored (potential) energy that has the ability to perform work.
How does pressure create flow?
it overcomes resistance
What is gravitational energy? When might two objects have the same amount?
A form of potential energy associated with elevated objects that can perform work. Two objects at the same height have the same gravitational energy.
In what ways is energy lost in the circulatory system?
Viscous, frictional, and inertial loss
What is viscous energy loss? How does it relate to hematocrit?
A thicker or more viscous fluid has more friction so it loses more energy than a thinner fluid. In blood, a lower amount of hematocrit would make blood less viscous which would reduce the energy loss.
What is frictional loss?
Frictional loss occurs when energy is transferred to heat. When the blood slides acrss the vessel walls and other layers, it creates heat but loses flow energy.
What is inertial energy loss?
Energy is lost when the speed changes, regardless of how it changes.
