Chapter 18 Flashcards
Hemodynamics
____ is the study of blood moving through the circulatory system.
Hemodynamics
____ indicates the volume of blood moving during a particular time.
Flow
The units for flow are:
liters/min, ml/sec
____ indicates the speed of a fluid moving from one location to another.
Velocity
The units for velocity are:
cm/sec, m/min
The three forms of flow are:
- Pulsatile
- Phasic
- Steady
____ flow occurs when blood moves with a variable velocity. Blood accelerates and decelerates from cardiac contraction. Common in arterial circulation.
Pulsatile
____ flow occurs when blood moves with a variable velocity. Blood accelerates and decelerates from respiration. Common in venous circulation.
Phasic
____ flow occurs when a fluid moves at a constant speed or velocity. Common in venous circulation when individuals stop breathing for a moment.
Steady
____ flow is characterized by layers of blood moving parallel to each other. Commonly found in normal physiologic states.
Laminar
Two forms of laminar flow are____ flow and ____ flow.
Plug and parabolic
In ____ flow, all the layers of blood travel at the same velocity.
Plug
In ____ flow, velocity of blood is highest in the center and decreases to the walls. Bullet shaped profile.
Parabolic
Reynolds number predicts whether flow is ____ or ____.
Laminar or turbulent
The Reynold’s number for laminar flow is < ____.
< 1500
The Reynold’s number for turbulent flow is > ____.
> 2000
____ flow is chaotic flow patterns moving at different speeds in many directions. Eddy currents or a vortex. Often found beyond a significant stenosis in a vessel.
Turbulent
Murmur or bruit are sounds associated with ____.
Turbulence
A ____ is a tissue vibration associated with turbulence.
Thrill
____ ____ is the total fluid energy at one location differs from the total fluid energy at a different location.
Energy gradient
Blood flows because of an ____ gradient.
Energy
____ energy is movement.
Kinetic
____ energy is a form of stored or potential energy. It has the ability to perform work.
Pressure
____ energy is a form of stored or potential energy. It has the ability to perform work
Gravitational
Kinetic energy is determined by what two factors?
- An object’s mass
- The speed at which it moves
____ is a major form of energy for circulating blood.
Pressure
As blood flow through the circulation, energy is lost in three ways:
- Viscous loss
- Frictional loss
- Inertial loss
____ describes the thickness of a fluid.
Viscosity
What is the unit for viscosity?
Units: Poise
____ the percentage of red blood cells in blood.
Hematocrit
The normal hematocrit value is about ____%.
45%
____ energy loss occurs when flow energy is converted to heat as one object rubs against another.
Frictional
____ energy loss occurs when the speed of a fluid changes (either faster or slower).
Inertial
A ____ is a narrowing in the lumen of a vessel.
Stenosis
____ ____ describes the relationship between velocity and pressure in a moving fluid.
Bournoulli’s principle
What is the equation for pressure gradient?
Pressure gradient = flow x resistance
____ ____ states that the movement of fluid through a tube and the movement of electricity through a wire are similar.
Ohm’s law
Resistance is determined by:
- Diameter – vasoconstriction/vasodilation
- Distance – length of vessel
- Viscosity – thickness of blood
- Friction – loss of energy as blood moves
- Inertia – push from heart/muscle
- Elasticity – expansion of vessel wall
____ are thin walled and collapsible.
Veins
During normal function, veins have ____ pressure and are only partially filled with blood.
Low
____ pressure is the pressure that determines the shape and volume of veins.
Transmural
____ pressure is related to the weight of blood pressing on a vessel, measured at a height above or below heart level.
Hydrostatic
What is the hydrostatic pressure at the top of the head?
-30 mmHg
What is the hydrostatic pressure at mid chest?
0 mmHg
What is the hydrostatic pressure at the the waist?
50 mmHg
What is the hydrostatic pressure at the knee?
75 mmHg
What is the hydrostatic pressure at the ankle?
100 mmHg
Blood pressure is determined by the ____ and the ____.
Volume of flow and the resistance to flow
During ____, the diaphragm moves down and creates a negative pressure in the chest.
Inspiration
During ____ the diaphragm moves up and increases pressure in the chest.
Expiration
What shape is a vein during normal function?
Hourglass
