Ch 9 Arterial Physiology Flashcards
What is inertia?
Tendency of body at rest to stay at rest
or
Tendency of body in motion to stay in motion
What is kinetic energy?
-Aka energy of work or motion
-Represented by velocity of blood flow
What is potential energy?
-Aka stored/resting energy
-It is the intravascular pressure, which distends vessels
-Pressure is supplied by the contraction of the heart
What is the bernoulli principle?
When fluid flows w/o change in velocity from 1 point to another, there is no frictional losses
What is ohm law?
Flow through 2 points is directly proportional to the potential difference across the 2 points, and inversely proportional to the resistance b/w them
What does capacitance mean?
-Measure of a blood vessels ability to increase the volume of blood it holds w/o a large increase in BP
-Ability of a vessel to store energy
The total energy of a system is made up of ___ + ___ energy?
Potential + kinetic
Blood will move from an area of ___ energy/pressure to an area of ___ energy/pressure?
High, lower
The highest pressure in the vascular system occurs where?
LV of heart, approx 120 mm Hg
The lowest pressure in the vascular system occurs where?
RA of heart, approx 2-6 mm Hg
What is gravitational potential energy?
-Potential for doing work, related to the force of gravity
-Ex. if blood is positioned above the RA, it has the ability to do work b/c gravity will act on the blood to move it downward
When would gravitational potential energy be reduced?
In dependent parts of the body (below RA)
What is hydrostatic pressure?
Pressure within vessels related to the reference point of the RA
When would hydrostatic pressure increase?
Increases in the lower portions of the body, the farther below the RA = the greater it is
Does gravitational potential energy + hydrostatic pressure cancel each other out?
Yes - b/c both formulas are the same but with an opposite sign
In the vascular system, energy is almost all dissipated in the form of ___ b/c of friction?
Heat
How does the bernoulli principle relate to pressure?
High pressure = low velocity
Low pressure = high velocity
(inverse of each other)
What is the most important influence on blood viscosity?
Hematocrit (concentration of RBCs)
Blood viscosity increases with an increase in ___?
Hematocrit
When would inertial loss occur?
Whenever blood is forced to change direction or velocity
(depends on the density + velocity of blood flow)
Velocity + flow are related by the following equation:
V = Q/A
(V = velocity, Q = blood flow, A = area)
Does velocity go faster or slower in a more narrow orifice?
Faster
(velocity + area are inversely related)
Which vessel has the largest cross-sectional area?
Capillaries (600x greater than the Ao, due to their large number)
(increases from Ao, arteries, arterioles, capillaries)
Which law describes flow as “steady laminar flow”?
Poiseuille’s law (although flow is actually pulsatile + does not tend to move in a laminar fashion)
