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25 Cards in this Set
- Front
- Back
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What is hemodynamics?
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The study of physical principles of blood circulation.
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What is blood?
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A vicous fluid made of cells and plasma
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What are RBC's?
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The major component of blood
Biconcave disks 7um in diameter Give signal to doppler |
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What is viscosity?
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The thickness of blood.
The thicker the blood (more RBC's) the more viscous it is. Anemia=low RBC=low viscosity |
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How blood moves through the vessels:
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Blood flows to path of least resistance
Pressure is applied to a vessel Blood is propelled through the vessel by a pressure drop |
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What does resistance determine and what changes it?
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How and where blood flows
Changed by viscosity, vessel lumen radius, frictional effects |
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What is laminar flow?
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When blood flows in layers
The center stream is always the highest velocity in this flow. |
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What is volume flow rate?
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The amount of blood flowing through a vessel per unit of time
Too fast=stenosis Too slow=blockage |
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Two biggest components to Poiseulle's equation:
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*Small radius changes make a difference (x4) in volume flow
*Volume flow is altered by pressure differences along the length of a vessel |
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Poiseulle's concepts
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Inverse relationship (change increases, flow rate increases, radius doesn't)
Vessel length I, volume flow rate D Viscosity I, volume flow rate D |
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Static filling pressure
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When vessels fill, the walls expand. When the vessel returns to its orginal shape, this pressure is called _________.
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What is hydrostatic pressure?
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The weight of fluid in a column/the weight of blood when standing due to gravity.
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In general circulation, what is considered the reference point, or 0 hydrostatic pressure?
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The atrium
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Anything above the reference point is _________
Anything below is a _________ pressure shift |
Negative
Positive |
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What is ABI?
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Ankle-Brachial-Index
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Bernoulli's principle states that total fluid energy consists of:
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Kinetic energy, potential energy, and work done when pressure is applied.
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What does Bernoulli's predict?
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Pressure drops greatly across a stenosis as a reults of energy loss on the post stenotic region.
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What is pulsatile flow?
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Blood flow that reflects the phases of the heartbeat
Used in arterial flow only |
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What is systole?
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Forward flow sent through the peripheral system
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What is early diastole?
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Area of tempory flow reversal
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What is late diastole?
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The forward flow reflective wave hits the proximal resistance to the next oncoming wave and then reverses.
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What is intraluminal pressure?
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Pressure exterted on the walls from the fluid within blood
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What is tissue pressure?
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Pressure exterted on the vessel from outside structures
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What is transluminal pressure?
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The difference between the intraluminal and tissue pressure, or the pressure on the wall itself
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When does turbulence occur?
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After Revnolds number
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