Hemodynamics Flashcards
What is required for blood to flow?
Pressure difference
When blood flows through the circulatory system, energy is lost due to ?
Textbook says friction between the layers of flowing blood
Dina’s notes say heat. Same thing I guess???
Stroke volume is the:
amount of blood that enters the arteries during a cardiac cycle
What influences blood flow? (9)
cardiac activity vessel compliance peripheral resistance branching vessels and collaterals vasoconstriction/dilation tone of vascular musculature blood viscosity exercise autoregulation
What is autoregulation?
constant blood flow - cerebral and renal vessels
vasodilation and vasoconstriction
What are the pumps in the circulatory system?
heart (primary pump) aortic pump muscles (venous system) gravity respiratory pump
The stretching of the aorta during peak systole allows the aorta to act as a “reservoir”. True or false.
True– this stores much of the blood expelled by the heart. During diastole the energy stored in the arterial walls dissipates the blood stored by forcing it into arteries
BP in venules? BP in great veins?
Venules- 16mmHg
GV- 4mmHg
Blood flow is determined by? (2)
blood pressure and peripheral vascular resistance
Arterial physiology depends on?
cardiac status
Increased heart rate yields an increased volume of blood flow to the tissues. True or false
True
Is the left or right side of the heart a higher pressure?
Left
Capillary bed consists of? (3)
arterioles, capillaries and venules
Each heart beat projects how much blood from the LV into the arterial tree?
70cc
Systemic vascular resistance (SVR) is what?
resistance offered by peripheral circulation
What is the main resistance vessel?
arterioles
What are the sources of peripheral resistance?
blood viscosity, vessel radius and total vessel length
Blood viscosity is affected by? (9)
smoking age diabetes obesity male gender anemia temperature cholesterol hypertension
Hematocrit:
percentage of red cells in the total blood volume
affects blood viscosity and resistance to flow
What are the relationships between vessel resistance and viscosity, radius and vessel length?
directly proportional to viscosity
inversely proportional to the radius to the fourth power
and
directly proportional to vessel length
Peripheral resistance is controlled by what 2 factors?
autoregulation (vasodilation and constriction)
sympathetic nervous system
Where does blood pressure take it’s biggest drop?
arterioles
Amount entering the arterial tree is determined by?
cardiac output
Amount exiting the arterial tree is determined by?
peripheral resistance and arterial pressure
According to ________ principle, there is a drop in blood pressure immediately after a stenosis.
Bernoulli’s
Within a stenosis, what happens to pressure and energy?
increase in velocity and energy, decrease in pressure
Venous compliance in approximately ___x more than arteries
30
Blood pressure is affected by?
vessel elasticity and peripheral resistance
Turbulent flow occurs at high velovcities. True or false
true–particular elements don’t travel along well-defined paths
Hemodynamically significant stenosis is a reduction in what 3 components?
volume, pressure and flow
Arterial pressure is ______ proximal to the site of narrowing and ____ distally
higher, lower
What is a tandem lesion?
two or more stenotic regions that have a more pronounced effect on distal pressure
Result is large losses of energy at the entrance and exit of the lesion
Blood flow proximal to a stenosis will appear to be what resistance pattern?
higher
The venous pressure of the lower limbs is comprised of what 3 main components?
hydrostatic pressure
muscular/residual pressure
and
residual pressure
What is residual pressure?
at the venous end of capillaries, the venous pressure supplied but arterial pressure
Are the changes in blood flow between upper and lower limbs during inspiration/expiration the same?
No, they’re opposite.
During inspiration, the blood flow increases for upper limbs and decreases for the lower limbs.
Vice versa for expiration
