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38 Cards in this Set
- Front
- Back
- 3rd side (hint)
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Flow |
Indicates the volume of blood moving during a particular time. |
How much? |
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Velocity |
Indicates the speed of a fluid moving from one location to another. |
How fast? |
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3 basic forms of blood flow |
* pulsatile * phasic * steady |
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Pulsatile flow |
When blood moves with variable velocity as result of cardiac contraction. |
In arterial circulation |
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Phasic flow |
When blood moves with variable velocity with respiration. |
In venous circulation |
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Steady flow |
When a fluid moves at a constant speed or velocity. |
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Laminar flow |
When the flow streamlines are aligned and parallel. |
Normal flow |
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2 forms of laminar flow |
* plug * parabolic |
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Plug flow |
When all layers & blood cells travel at same velocity. |
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Parabolic |
Velocity highest in center of lumen, and gradually decreases to the vessel wall. |
Bullet-shaped profile |
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Turbulent flow |
Chaotic flow pattern in many directions & at many speeds. |
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Murmur / bruit |
Sound associated with turbulence. |
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Thrill |
Tissue vibration associated with turbulence. |
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Reynolds number |
Predicts whether flow is laminar or turbulent. Laminar < 1500 Turbulent > 2000 |
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Forms of energy |
* kinetic * pressure * gravitational |
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Kinetic energy |
Associated with a moving object, determined by mass & speed. |
Ping-pong vs golf ball |
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Pressure energy |
A form of stored or potential energy, has the ability to do work. |
Whipped cream can |
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Gravitational energy |
Also stored or potential energy associated with elevated object. |
Slide a hill vs flat surface |
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3 ways of energy loss |
* viscous * frictional * inertial |
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Viscosity |
Thickness of a fluid. More loss with high viscosity. |
Honey vs alcohol |
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Hematocrit |
The percentage of blood made of RBC. Normal is 45% |
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Frictional |
When flow energy converted to heat as objects rub. |
Blood sliding across vessel |
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Inertia |
Relates to tendency of fluid to resist changes in its velocity. |
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3 events of inertial loss |
* Pulsatile flow * phasic flow * stenosis |
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Stenosis |
Narrowing of the lumen of a vessel. |
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Effects of a stenosis |
* change in flow direction * increase velocity as narrows * turbulence distal to stenosis * Press.Grad.across the stenosis * loss of pulsatility |
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Bernoulli's principle |
Relationship between velocity & pressure in a moving fluid. Simply stated sum of kinetic & pressure remains constant. |
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KNOW !! |
Blood flows from high pressure to low pressure. |
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Pressure gradient increases when... |
* flow increases * resistance increases |
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Flow increases when ... |
* pressure gradient increases * resistance decreases |
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Hydrostatic pressure |
Related to weight of blood pressing on a vessel measured above or below heart level. |
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Hydrostatic pressure is zero everywhere when patient is ... |
Supine |
Laying flat on back |
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2 reasons respiration affects venous flow |
* venous is low pressure * muscles alter thorax & abdomen |
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2 venous flows affected by breathing |
* venous flow in legs * venous return to the heart |
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Inspiration |
* diaphragm down to abdomen * thoracic pressure decreases * abdominal pressure increases * venous return increases * venous flow in legs decrease |
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Expiration |
* diaphragm upward to thorax * thoracic pressure increases * abdominal pressure decrease * venous return decreases * venous flow in legs increase |
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When venous flow in legs decrease .. |
Venous return to heart increases |
Inversely related |
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When venous flow in legs increase ... |
Venous return to heart decreases |
Inversely related |
