Physics Ch. 18 Flashcards
Study of blood moving through the circulatory system
hemodynamics
Flow (volume flow rate) indicates the _____ of blood moving _______
volume, during a particular time
Indicates speed of a fluid moving from one location to another
velocity
What are the 3 forms of blood flow
pulsatile, phasic, steady
Occurs when blood moves with variable velocity
Pulsatile
In pulsatile flow, blood accelerates and decelerates as a result of
cardiac contraction
Pulsatile flow commonly appears in
arterial circulation
Occurs when blood moves at a variable velocity
phasic
In phasic flow, blood accelerates and decelerates as a result of
respiration
Phasic flow commonly appears in
venous circulation
Occurs when a fluid moves at a constant speed or velocity
steady
Steady flow is present in venous circulation with
helps inspiration or held expiration
Occurs when the flow streamlines are aligned and parallel
laminar flow
Laminar flow is characterized by _____ of blood that travel at
layers, individual speeds
Laminar flow is
silent
All the layers and blood cells travel at the same velocity
plug flow
Bullet-shaped- velocity is highest in the center of the lumen and gradually decreases as it gets closer to the vessel wall
parabolic flow
Characterized by chaotic flow patterns in many different directions and at many velocities, streamlines are often obliterated
turbulent flow
Turbulent flow creates swirling pattern. These are called
eddy currents
Turbulent flow is associated with _____ pathology and elevated/increased blood velocities
cardiovascular
Sound associated with turbulence is called
murmur or bruit
Tissue vibration associated with turbulent flow is called a
thrill (palpable murmur)
Predicts whether flow is laminar or turbulent, unitless number
reynolds number
Reynolds number is less than 1500
laminar flow
Reynolds number is greater than 2000
turbulent flow
Blood moves from regions of _______ to _______. What is this called
higher energy to lower energy, energy gradient
What provides energy to blood
the contraction of the heart in systole
What are the 3 forms of energy
kinetic, pressure, gravitational
Total energy at a specific location within the circulation is the
sum of all 3 energy forms
Associated with a moving object
kinetic energy
What is kinetic energy determined by
objects mass, speed at which it moves
Stored or potential energy, major form of energy for circulating blood and creates flow by overcoming _____
pressure energy, resistance
Associated with any elevated object, also a form of stored or potential energy
gravitational energy
3 energy losses in circulation
viscous loss, frictional loss and inertial loss
Describes the thickness of a fluid
viscosity
More energy is lost with movement of ______ viscosity fluids
high
Viscosity is measured in units of
poise
Viscous energy loss in blood is determined by the
hematocrit
Losses that occur when flow energy is converted to heat as an object rubs against the other
frictional
Blood sliding across a vessel wall creates
heat
Relates to the tendency of a fluid to resist changes in its velocity
inertia
Inertial energy loss occurs during what 3 events
pulsatile, phasic, stenosis
Pulsatile flow happens during _____ circulation
arterial
Phasic flow happens during ______ circulation
venous
Velocity change at a narrowing in the lumen of a vessel
stenosis
Effects a stenosis has on blood flow
changes in direction, increase in velocity, post stenotic turbulence, pressure gradient
Pressure downstream from the stenosis (after) is _____ than the pressure upstream (before)
lower
Describes the relationship between velocity and pressure in a moving fluid
bernoulli’s principle
Bernoulli’s principle is derived from the principle of
conservation of energy
The principle states, with a STEADY flow, the _______ forms of energy is the same everywhere
the sum of all
States energy is neither created nor destroyed, but simply converted from one form to another
law of conservation of energy
Veins have ____ walls and are ______
thin, collapsible
During normal functions, veins have ____ pressure and only partially expand
low
During exercise, the pressure ____ in the veins and they appear more round
increases
Veins can accommodate large volume increases with
small pressure increases
Pressure related to the weight of blood pressing on a vessel measured at the height above or below heart level
hydrostatic pressure
If blood measurement is made at the level of the heart, the hydrostatic pressure is ____ and _____
0mmHg, no error in measurement
If the blood pressure measurement is made _____ the level of the heart, the measured blood pressure is erroneously high
below
If the blood pressure measurement is made ____ the level of the heart, the measured blood pressure is erroneously low
above
During inspiration, the diaphragm moves ______, the chest cavity _____ and there is a _____ in chest pressure, abdominal pressure _____, venous return to the heart ______, venous flow in the legs ______
downward, expands, decrease, increases, increases, decreases
During expiration, the diaphragm moves _____, chest pressure ______, abdominal cavity pressure _____, venous return to the heart _____ and venous flow in the legs ______
upward, increases, decreases, decreases, increases
Measured pressure is the sum of
hydrostatic pressure and circulatory pressure (bp)
Normally what happens to venous flow in the legs during inspiration
venous flow in legs decreases
What does not happen during expiration
abdominal pressure increase
