Hemodyamics group 2 chap 18 Flashcards
What is flow
the volume of blood moving during a particular time
what is velocity
speed of fluid moving from one location to another
what is velocity
speed of fluid moving from one location to another
what flow is associated cardiac contraction
pulsatile
what flow is associated with respiration
phasic flow
what is the reynolds number for laminar flow
less than 1,500
laminar flow is characterized by
layers of blood that travel at individual speeds
laminar flow patterns are commonly found in
normal physiologic states
plug flow occurs when
all of the layers and blood cells travel at the same velocity
parabolic flow has a what shape?
BULLET
• most common flow type
what flow is associated with pathology?
Turbulent flow
velocity is the highest in ___ of the lumen
center
in a vein that has a stenosis where is the pressure lowest
narrowest
and velocity is higher
Where is the greatest resistance in a vessel with stenosis?
in stenosis
Blood flow near the vessel wall has more or less resistance?
more
a longer vessel has _ resistance and a shorter vessel has a _ resistance
higher, lower
what is reynolds’s number for turbulent flow
greater than 2000
in stenosis pressure _ and velocity _
decreases, increases
what happens to the veins in the arms when you inhales vs. the veins in the legs?
In the arms, pressure increases
In the legs, pressure decreases
What two factors determine kinetic energy?
An object’s mass and the speed at which it moves
high blood pressure with no resistance has a high or low flow rate?
high
How does blood flow in an energy gradient?
from areas of high energy to low energy
normally what happens to venous flow in the legs during inspiration?
decreases
What is energy gradient?
when blood moves from regions of higher energy to lower energy
what will make resistance increase
vessel size, blood thickness and stenosis
electrical resistance is reported in?
ohms
What factor determines viscous energy blood loss?
Hematocrit
Blood pressure increases and has no change in resistance. How is the flow rate?
fast
Viscosity is measured in units of _.
Poise
what is the bernoullis principle?
describes the relationship between velocity and pressure in a moving fluid
in the circulatory system, the resistance vessels are called
arterioles
As blood flows through the circulatory system, energy is lost in three ways:
Viscous loss, frictional loss, and inertial loss
where does turbulence occur in a vessel with stenosis?
distol
Blood closest to the wall has more or less resistance compared to blood in the center?
More
How is flow volume increased?
An increase in pressure difference
Do longer vessels increase or decrease resistance?
Increase
What type of energy loss relates to the tendency of a fluid to resist changes in its velocity?
Inertia
When an object must change directions or velocities, it:
Loses energy
What are the three times that inertial energy loss occurs in the circulatory system?
Pulsatile flow, phasic flow, and velocity changes at a stenosis
