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30 Cards in this Set
- Front
- Back
Normally, what happens to venous flow in the legs during inspiration?
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Venous flow in the legs decreases during inspiration
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_______ indicates the volume of blood moving during a particular time
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Flow
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the speed or swiftness of a fluid moving from one location to another
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Velocity
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3 basic forms of blood flow
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Pulsatile, Phasic, and Steady
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Pulsatile
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when blood moves with a variable velocity. appears with arterial circulation
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Phasic Flow
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blood moves with variable velocity. accelerates and decelerates with respiration. Appears with venous circulation
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Laminar Flow
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means layer. Commonly found in normal physiology.
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Plug flow
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type of laminar flow. When all layers of blood flow at same velocity
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Parabolic
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type of laminar flow. bullet shaped. Velocity is highest in the center of the vessel
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Reynolds Number
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predicts whether blood flow is laminar or turbulent. 1,500-2,000
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Turbulent Flow
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chaotic flow patterns in many different directions and speeds. Often associated with pathology.
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Sound associated with turbulent flow
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murmur (heart), & bruit (vessel)
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Thrill
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VIBRATION associated with turbulence
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Energy Gradient
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when blood moves from regions of HIGHER energy to LOWER energy
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What provides energy to the circulating blood?
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the contraction of the heart during systole
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Kinetic Energy
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associated with a moving object. determined by object's MASS and SPEED. Heavy, swiftly moving objects have lots of kinetic energy
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Pressure Energy
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stored or potential energy. Creates flow by overcoming resistance
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Energy losses in Circulation
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1. Viscous loss
2. Frictional loss 3. Inertial loss |
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Viscous Energy Loss
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Describes thickness of blood. More energy lost with high viscosity fluids. Units-Poise. determined by Hematocrit
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Frictional Energy Loss
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when flow energy is converted to heat as one object rubs against another.
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Inertial Energy Loss
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Energy lost when speed of fluid changes.Tendency of a fluid to resist changes in velocity
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Stenosis
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narrowing of the lumen in a vessel.
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Where is the highest velocity in a stenotic vessel?
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where the vessel is most narrow
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Pressure Gradient across stenosis
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Post-stenotic pressure is lower than the pressure before the stenosis
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Effects of Stenosis
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-loss of pulsatility
-change in flow direction -post-stenotic turblence -increased velocity where vessel narrows |
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Bernoulli's Principle
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describes relationship between VELOCITY and PRESSURE. the sum of kinetic energy and pressure energy remains constant
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Venous Hemodynamics
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have low pressure normally. As venous pressure increases the vessel becomes more round
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Hydrostatic Pressure
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the weight of blood pressing on a vessel when measured above or below heart level. mmHg.
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When a person is supine, what is the hydrostatic pressure?
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the Hydrostatic pressure is 0, everywhere
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circulatory pressure + hyrdrostatic pressure=
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measured pressure.
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