Ch.16 Flashcards
Characteristics of blood flow and a vessel’s ability to perfuse a downstream organ is assessed using
color and spectral doppler.
Color doppler
allows for rapid identification of vessels, flow direction and high velocity jets that signify disturbance to flow
Duplex doppler
supplies both structural and functional information of a vessel.
Abdominal arterial system consists of
the segment of the aorta from the level of the diaphragm to the aorta bifurcation
Celia artery located
1-3cm below diaphragm,12th thoracic and 1st lumbar vertebrae.
Which renal artery is longer?
Right renal artery because it must pass posterior to IVC and right renal vein to enter the hilum of right kidney.
right renal artery is___than right renal artery
higher
Percentage of population who have anatomic variants to the mesenteric vessels, with most common an anomalous origin of right hepatic artery
20%
majority of identified replaced right hepatic artery anomalies originate as
a branch of the SMA
% of population with duplicated/accesory renal arteries
20%
Accessory renal arteries usually enter
upper or lower poles of kidney rather than entering the organ at the hilum.
-Are found more often on left side than right
Collagen fibers that make abdominal artery walls look bright are found in the
Tunica intima and Tunica media
hemodynamics
-defines physical factors that control blood flow within the human body
-is depending on potential,kinetic and gravitational energy as well as size, elasticity and geometry of blood vessel.
Theories related to fluid dynamics that have been used to gain understanding of blood flow within body
Poiseuille’s law,bernoulli’s law, ohm’s law and law of conversation of energy
Poiseulle’s law
predicts volume of flow in moving fluids.
-parameters used to determine impact flow include : pressure gradient, radius,length of a tube and viscosity of the fluid.
greater the pressure gradient ,greater the flow
Poiseuille’s law
what has greatest impact on flow?
the inverse relationship of the tubes radius ,because it is to the 4th power
Ohm’s law
Electrical current is directly proportional to the voltage and inversely related to resistance
Bernoulli’s principle
Conservation of energy.Energy cannot be destroyed but it can altered from 1 form to another.
-In a closed system,all energy at 1 location must equal all energy in another location
What impacts the way blood flows within a vessel?
blood viscosity ,size and configuration of the vessel and smoothness of the lumen.
Blood flow in a normal vessel is described as
Laminar
2 types of blood laminar
parabolic and plug flow
Laminar flow is
described as concentric layers of blood that move parallel to each other in an orderly and predictable manner
-faster velocity in the center of vessel and slowest along vessel walls,creating bullet shaped flow profile called parabolic flow
Bullet shaped flow profile
parabolic flow
Plug flow is found at
the entrance or origin of a vessel.
Distributing vessels have
a thicker tunica media due to an increase in smooth muscles
Conducting vessels like aorta have
large amount of elastic fibers that allow it to expand to propel blood forward during systole
Have greatest amount of smooth muscle and dilate and constrict selectively to meet the metabolic needs of an organ or tissue
Arterioles
capillaries are composed of
a single endothelial layer
smallest most numerous vessels in the body
-responsble f
Stroke volume and cardiac output
impact the volume and velocity of blood flow through the body
systole
forces blood out of the heart and into the conducting vessels of the circulatory system
pressure that is stored in the artery walls propels the blood forward in
Diastole
Peripheral resistance
controls the volume and velocity of blood flow into specific regions of the body
primary role of arterioles
altering resistance
Named the resistive component of the circulatory system
Arterioles
Through ______ and_____ the arterioles alter the flow from pulsatile within larger vessels to a constant steady flow within the capillaries.
Through vasoconstriction and vasodilation
Velocity of flow must____ to allow transfer of oxygen and nutrients to tissues and transport waste products into the venous system, to be returned to the heart and restart the cycle
Decrease
Required to maintain the velocity of flow
a vast capillary network
Pulsed doppler utilizes____to visualize the doppler signal and display physiologic date of blood flow
spectral analysis
To accurately evaluate hemodynamic functions and obtain velocity information
an angle of intonation of 60 degrees or less with respect to the blood flow vectors and the vessel walls should be used.
Sample volume
gate along with an angle correction
Obtains blood velocity, direction of flow and downstream resistance from a specific region within a specific blood vessel.
Spectral doppler (pulsed wave)
has both a systolic and diastole component in its waveform
Laminar flow is characterized by
an uniform systolic velocity ,a “window”,an area absent of doppler shifts under the systolic component.
Spectral broadening
thickening of the velocity spectral envelope
What can affect the peak systolic velocity of a normal aorta?
age, gender,body habits and cardiac output
-normal peak systolic velocity ranges from 40 to 100 cm/s
minimal or reverse diastolic flow
below the baseline flow
Celiac artery supplies
low resistance end organs–the liver and spleen…through the hepatic, left gastric and splenic arteries
Hepatic artery responsible for ___ of the oxygenated blood supply to liver.
30%
Low resistance organs
brain, eyes,liver and spleen
-demand constant blood flow to moderate their metabolic activity.
hemodynamic flow patterns in normal renal arteries that supply healthy kidneys demonstrate
high diastolic flow
vessels consistently visualized entering IVC are
common iliac veins, renal veins and hepatic veins
Dilatation can also occur in the presence of
congestive heart failure, tricuspid regurgitation or any other condition that results in increased right atrial pressure.
Are boundary formers within the liver, coursing horizontally toward ICV
Hepatic veins
Considered the capacitive side
The venous side of the circulatory system.
-approximately two thirds of total blood volume is stored within veins
the _____ in the vein has less smooth muscle than an artery
tunica media
extremity veins have___
bicuspid valves ,which have a direct extension of the intima layer
transmural pressure
determines the cross sectional shape of the veins
high transmural pressure
in a fully distended state, the vein will be circular in shape and offer almost no resistance flow
Low transmural pressure
vein has a partially collapsed lumen that creates a high resistance to flow.
During inspiration,diapraghm ___
During expiration,diapraghm ____
descends (goes down)
Ascends
hepatofugal
away from liver
normal venous doppler signals should exhibit
Spontaneity,phasicity,augmentation,compency and non pulsability.
responsible for approximately 70& of oxygenated blood supple to liver
portal vein and its branches
hepatopedal
towards the liver.
Portal venous flow accelerates during expiration and decelerates during inspiration
