Chapter 5: Arterial Physiology Flashcards
The tendency of a body at rest to stay at rest or a body in a motion to stay in motion
inertia
The energy of work or motion; in the vascular system, it is, in part, represented by the velocity of blood flow
kinetic energy
Flow of a liquid in which it travels smoothly in parallel layers
laminar flow
The law that states the volume of a liquid flowing through a vessel is directly proportional to the pressure of the liquid and the fourth power of the radius and is inversely proportional to the viscosity of the liquid and the length of the vessel
Poiseuille’s Law
The stored or resting energy; in the vascular system, it is the intravascular pressure
potential energy
The property of a fluid that resists the force tending to cause fluid to flow
viscosity
Total energy of a system is made up of both _____ and _____ energy.
potential
kinetic
stored or resting energy; represented primarily by intravascular pressure which distends vessels; supplied by contraction of heart
potential energy
energy of work or motion
kinetic energy
highest pressure equal to 120 mm HG is found:
left ventricle of heart
Lowest pressure equal to 2-6 mm Hg
right atrium of heart
potential for doing work related to force of gravity
gravitational potential energy
pressure within vessels related to reference point of right atrium
hydrostatic pressure
The farther below the reference point, the _____ the hydrostatic pressure.
greater
Gravitational potential energy and hydrostatic pressure tend to:
cancel each other out
describes the relationship of energy, velocity, and pressure
Bernoulli Principle
when a fluid flows without a change in velocity from one point to another, the total energy content remains constant, providing no frictional losses
Bernoulli Principle
Energy is almost all dissipated in the form of heat because of ____.
friction
balance between potential energy (pressure) and kinetic energy (velocity)
total energy
If the velocity of blood goes up, there must be a pressure ____>
decrease
Energy “losses” are the result of ____ and ____.
viscosity
inertia
the property of a fluid that resists the force tending to cause fluid to flow; friction existing between bordering layers of fluid
viscosity
_____ increases with increases in hematocrit
viscosity
most important influence of blood viscosity
hematocrit
tendency of a body at rest to stay at rest or a body in motion to stay in motion unless acted upon by an outside forece
inertia
occur whenever blood is forced to change direction
inertial losses
Energy losses because of viscosity effects are ____ than those because of inertia
greater
rate of movement (displacement) with respect to time
velocity
units of velocity
distance per unit of time
cm/s; m/s
also referred to as volume flow
blood flow
represents the volume of something moved per unit of time
blood flow
units of blood flow
mL/s; L/s; mL/min; L/min
Velocity will vary inversely with _______
cross sectional area
velocity must ____ if area of a blood vessel decreases/
increase
The cross sectional area _____ moving from aorta, through arteries, then arterioles, into capillaries
increases
Blood velocity _____ as blood travels from aorta, through arteries, then arterioles, into capillaries
decreases
Why is the slowing down of blood flow important at the capillaries?
important in proper exchange of nutrients and waste
As blood is returned to the heart, velocity _____.
increases
describes the steady laminar flow of Newtonian fluids
Poiseuille’s Law
refers to a system where flow is nonpulsatile
steady flow
flow that moves in a series of layers
laminar flow
homogeneous fluid
Newtonian fluid
used to define pressure/flow relationships
Poiseuille’s Law
A greater change in pressure will produce a(n) _____ in flow.
increase
If viscosity of blood increases, flow will ____.
decrease
radius of a vessel is directly proportional to
flow
most important determinant of blood flow
radius of blood vessel
states that the current (flow) through two points is directly proportional to the potential difference or voltage across the two points and inversely proportional to the resistance between them
Ohm’s Law
What varies resistance by altering vessel radius?
smooth muscle cell layer within media of wall of vessel
For resistance in series, the total resistance equals to the sum of _______
individual resistances
For resistances in parallel, the _____ of the total resistance of the system equals the sum of the reciprocals of the individual resistances
reciprocal
The more parallel elements in a network, the _____ the overall resistance
lower
antegrade flow throughout cardiac cycle
low-resistance flow
low-resistance flow arteries
internal carotid
vertebral
celiac
splenic
hepatic
renal
displays both antegrade and retrograde flow
high-resistance flow
Radius of vessel decreases, _____ resistance to flow
increases
arteries with high-resistance flow
external carotid
subclavian
distal aorta
iliac
fasting superior mesentary
resting peripheral arteries
Low resistance pattern results in a(n) _____ in blood flow to meet the increased metabolic demands
increase
entrance to a vessel flow; all elements of blood flow stream will have the same velocities
plug flow
Velocity is equal to approximately _____ the mean velocity across the entire cross section.
twice
irregular motions of fluid elements
turbulent flow
dimensionless quantity
Reynolds number
proportional to inertial forces and to viscous forces acting on a fluid
Reynolds number
directly proportional to velocity of blood, density of blood, and radius of vessels
Reynolds number
inversely proportional to viscosity of blood
Reynolds number
Re below 2000
flow will be laminar flow
Re above 2000
turbulence will develop
Principal function of the arterial system
distribute blood to the capillary beds throughout body
converts intermittent (pulsatile) output of heart to a steady flow through capillaries
hydraulic filtering
entire stroke volume discharged; part of energy of cardiac contraction dissipated as kinetic energy of the forward blood flow; remained stored as potential energy by distensible arteries
systole
elastic recoil of arterial wall converts potential energy into blood flow; produces antegrade flow late in cycle
diastole
change in volume divided by the change in pressure represents ______.
capicitance or compliance
the difference between systolic and diastolic pressures
pulse pressure
arterioles are known as _____ vessels
resistance
nerve fibers release norepinephrine because it causes:
an increase in tone of arterioles
resistance vessels _____ in response to high blood pressure and ____ in response to low blood pressure
dilate
constrict
2 lesions that are areas of concern for artherosclerosis
fibrous and complicated plaque
smooth surface, composed of smooth muscle and fibrous tissue, lacks calcification
fibrous plaque
irregular surface, loss of normal endothelium and calcification present
complicated plaque
Viscous energy losses within a stenosis are inversely proportional to _______ and directly proportional to its ____.
fourth power of radius
length
small change in radius = ____ change in flow
large
Doubling in length yields a _____ in associated energy losses
doubling
Decrease in radius by half will _____ energy losses by a factor of 16.
increase
degree of narrowing at which pressure and flow begin to be affected
critical stenosis
Changes in pressure and flow do not occur until cross-sectional area has been reduced by ___%>
75
preexisting pathways that enlarge with a stenosis or occlusion
collateral vessels
Collateral vessels are divided into:
stem arteries, midzone collaterals, reentry arteries
Blood flow increases with exercise to at least ____ times resting flow
3-5
Energy within the vascular system is made up of potential energy stored as _________ and kinetic energy represented by the _____.
intravascular pressure
velocity of moving blood
The hemodynamics of the arterial system includes unique relationships between ____, ______, and ____>
pressure
resistance
flow
Blood flow is determined by changes in ____ and _____.
pressure
resistance
The greatest impact to blood flow is the ______.
radius of a blood vessel
______ are the main source of resistance within the vascular system
arterioles
the energy of work or motion; in the vascular system, it is in part represented by the velocity of blood flow
kinetic energy
the stored or resting energy; in the vascular system, it is the intravascular pressure
potential energy
Flow of a liquid in which it travels smoothly in parallel layers
laminar flow
the law that states the volume flow of a liquid flowing through a vessel is directly proportional to the pressure of the liquid and the fourth power of the radius and is inversely proportional to the viscosity of the liquid and length of the vessel
Poiseuille’s Law
the tendency of a body at rest to stay at rest or a body in motion to stay in motion
inertia
The property of a fluid that resists the force tending to cause fluid to flow
viscosity
Where in the vascular system is the lowest energy represented by the lowest pressure located?
the right atrium
Which of the following statements regarding gravitational energy and hydrostatic pressure is FALSE?
a. they are components of the total energy in the vascular system
b. They tend to cancel each other out
c. They are components of the kinetic energy in the vascular system
d. They are expressed in relation to a reference point
c
What causes blood in the vascular system to move from point to the next?
pressure or energy gradient
In the entire vascular system, how does the cross-sectional area of vessels change?
increases from the aorta to the capillary level
Which of the following statements regarding the velocity of blood flow is FALSE?
a. velocity refers to the rate of displacement of blood in time
b. the velocity of blood increases from the capillaries to the venous system
c. the velocity of blood increases from the aorta to the capillaries
d. the velocity of blood changes with cross-sectional areas of the vessels
c
Which of the following could NOT be used as a unit to measure flow volume?
a. mL/s
b. m/s
c.cL/min
d. L/min
v
In the vascular system, what represents the potential difference or voltage in Ohm’s law?
pressure gradient
Changes in which of the following will most significantly affect resistance in the vascular system?
a. volume flow
b. velocity
c. viscosity of blood
d. radius of vessels
d
When vessels are arranged in parallel, how does this affect the entire system?
lower total resistance than when vessels are in series
Which of the following characterizes low-resistance flow?
a. retrograde flow
b. alternating antegrade/retrograde flow
c. antegrade flow
d. constriction of arteriolar bed
c
Which of the following characteristics regarding high-resistance flow is false?
a. the flow profile may be two to three phases
b. the flow displays alternating antegrade/retrograde flow
c. the flow profile is owing to vasoconstriction of arterioles
d. the flow profile is owing to vasodilation of arterioles
d
What flow profile is typically demonstrated at the entrance of a vessel?
plug flow
Which of the following statements regarding laminar flow is FALSE?
a. the layers of cells at the center of the vessels move the fastest
b. the layers of cells at the wall of the vessels do not move
c. The velocity at the center of the vessels is half the mean velocity
d. The difference in velocities between layers is owing to friction
c
What is required to move blood flow in a turbulent system?
greater pressure
What is the function of the hydraulic filter of the arterial system (composed of elastic arteries and high-resistance arterioles)?
distribute flow to the capillaries
In diastole, how is the conversion of potential energy into blood flow accomplished?
elastic recoil of the arteries
How is the resistance in the arterial system controlled/
by the contraction and relaxation of smooth muscle cells in the media of arterioles
Which of the following will result when norepinephrine is released by the sympathetic nervous system?
a. the relaxation of smooth muscle cells in arterioles is triggered
b. the contraction of smooth muscle cells is triggered
c. no effect on the smooth muscle cells in arterioles
d. no effect on the tone of the arteriole walls
b
Most prominently, abnormal energy losses in the arterial system would result from pathologies such as obstruction and/or stenoses because of which of the following?
a. the increased length of the stenosis
b. the friction from the atherosclerotic plawue
c. the decrease in the vessel’s radius
d. the increased viscosity
c
Which of the following statements about collateral vessels is FALSE?
a. collaterals are preexisting pathways
b. the resistance in collaterals is mostly fixed
c. vasodilator drugs have a large effect on collaterals
d. midzone collaterals are small intramuscular branches
c
In the human body, the major component of the blood influencing viscosity is ____.
hematocrit
The highest pressure in the vascular system is found in the _____.
left ventricle of the heart
When moving farther from the reference point of the right atrium, the hydrostatic pressure is _____.
reduced
The principle stating that the total energy remains constant from one point to another without changes in flow velocity is _____.
Bernoulli’s Principle
Inertia and viscosity are two components of the vascular system contributing to ____.
energy “losses”
In the vascular system, if the volume of blood or flow remains the same, a decrease in the area of a vessel should trigger a(n) ______ in the velocity of blood.
increase
The law defined by the statement that the current through two points is directly proportional to the potential difference across the two points and inversely proportional to the resistance between them is _____.
Ohm’s law
The total resistance in a system where the elements are arranged in a series is the ____ of the individual resistances/
sum
A low-resistance flow profile characteristically displays ______ flow throughout the cardiac cycle/
antegrade
The third antegrade phase seen in a high-resistance flow profile is related to _____ of the proximal vessels.
compliance
After exercise, under normal conditions, the resistance of the tissue bed in the lower extremities will change from _______.
high resistance to low resistance
In laminar flow, the “layers” of cells at the center of the vessel move _____ than the layers closest to the wall of the vessel.
faster
Turbulence in a blood vessel is mostly the result of change in the velocity of blood and the ____ of the vessel.
radius
The Reynolds number above which turbulence of flow starts to occur is _____.
2000
The arterial system can be compared to the ______ of the resistance-capicitance filters of an electrical circuit.
hydraulic filter
Pulse pressure in the arterial system is the difference between _____ and ______ pressure.
systolic
diastolic
An example of a local feedback mechanism that controls blood flow is that a drop in interstitial _____ will trigger the arterioles to dilate.
oxygen
In an area of atherosclerotic plaque, the exposure of the subendothelial collagen matrix is _______ and may cause platelet accumulation.
thrombogenic
Energy losses caused by stenosis will be more pronounced with less diameter reduction in a ____ resistance system.
low
Under normal conditions with exercise, blood flow _____ by at least three to five times the resting value.
increases
