Vascular Anatomy and Upper Extremities Flashcards
Do upper or lower extremity veins have thicker walls?
Lower
What is the vaso vasorum?
Small blood vessels within the walls of larger arteries and veins
What structure is the principle point of resistance to blood flow within the vascular system?
Arterioles
Name the largest arteries in the body
- Aorta
- Brachiocephalic Trunk
- L CCA
- L subclavian
- Internal iliacs
What is the thickest layer of a vein?
Tunica adventitia
What are the major veins in the body?
- SVC
- IVC
- Portal vein
What are the walls of capillaries known as?
Lined with endothelial cells known as ‘intima’
Where do the vertebral arteries arise from?
Subclavian artery
The subclavian artery gives rise to which two vessels?
- Vertebral arteries
- Internal mammary arteries
What does the brachial artery branch into?
Ulnar and radial arteries
The superficial palmer arch is completed by a branch of what?
The radial artery
The deep palmer arch is completed by a branch of what?
The ulnar artery
Is the radial or ulnar artery larger?
Ulnar
What will show in the vertebral artery with subclavian steal?
Retrograde flow due to blood flowing from vertebral artery into subclavian
In what vessels may demonstrate subclavian steal?
- L subclavian
- R brachiocephalic
What are the three most superficial veins in the upper extremity?
- Cephalic
- Basilic
- Medial antebrachial veins
What helps to form the medial antebrachial veins?
Palmer digital veins
What does the medial antebrachial vein drain into?
Basilic vein
What are the deep veins?
- Subclavian
- Axillary
- Brachial veins
What is the lowest pressure chamber and was it the pressure range?
Right atria: 2-6 mmHg
Where is hydrostatic pressure the greatest in the body?
Lower portions due to the weight of the column of blood in the vessels
What is hydrostatic pressure?
Pressure within the vessels related to the reference point of the R atrium
Total energies in the vascular system is a combination of what types of energy?
Potential and kinetic
Potential energy denotes what whereas kinetic energy denotes what?
Potential energy = pressure
Kinetic energy = velocity
What is the most important influencer of the viscosity of blood?
Amount of hematocrit
What do inertial losses of energy depend on?
Density and velocity of blood flow
What is the velocity equation in terms of blood flow?
V = Q/A
Q = blood flow
A= cross sectional area of a vessel
Where is the cross-sectional area the LARGEST in the arterial system of the body?
The capillaries because there are so many more capillaries in the body than any other artery and combined make up the largest area.
How many times greater is the cross-sectional area of the capillaries in relation to Ao?
600x greater
What law describes steady laminar flow?
Poiseuille Law
What component has the greatest impact on flow and why? (hint: think poiseuille law)
radius because it is raised to the 4th power in the equation
A decrease in radius of a vessel by half will increase the energy loss by how much?
A factor of 16 (hint: look at the formula)
Hemodynamic resistance is described by what law?
Ohm’s Law
R = change in pressure/Q (flow)
What is the equation of Ohm’s law?
R = change in pressure/blood flow
Changes in resistance are virtually all because of variations in what?
Radius
When there is an increase in number of vessels running parallel to one another, what happens to the resistance?
It decreases in resistance
How to calculate total resistance in an entire system?
The sum of each individual resistance:
R (total) = R1 + R2 + R3 etc.
How to calculate resistance of vessels running in PARALLEL?
1/R(total) = 1/R1 + 1/R2 + 1/R3 etc.
Will low resistance flow profiles have retrograde or antegrade flow throughout the cardiac cycle?
ANTEGRADE
Will high resistance flow profile usually have retrograde or antegrade flow throughout the cardiac cycle?
Both.
Antegrade during systole
Retrograde during early diastole. Flow reversal occurs in early diastole due to vasoconstriction of distal arterioles and therefore, decreasing the radius will increase resistance.
What arteries display high resistance?
- External carotid
- Subclavian
- Distal Ao
- Iliac
- If fasting = SMA
- If resting = peripheral arteries
Describe 2 ways to turn high resistance into low resistance?
After exercise when extremity arteries dilate due to increased demand of oxygen and nutrients, it becomes less resistant.
After eating when SMA dilates to meet increased metabolic demand
What type of flow does Reynolds number describe?
Turbulent
What is Reynolds number equation?
Re = (density x velocity x radius) / viscosity
Turbulence usually occurs due to changes in what factors?
Velocity and radius
What Re is considered laminar and turbulent?
<2000 = laminar
> 2000 = Turbulent
What converts pulsatile output of the heart to a steady flow through capillaries?
Hydraulic filtering
What characteristic of the arterial walls converts potential energy into blood flow during diastole?
Elastic recoil of arterial walls which causes antegrade flow in late diastole
What is known as the “ability of a vessel to store energy” without a large change in pressure?
Capacitance (change in volume/change in pressure)
What is the formula for capacitance?
Change in volume / change in pressure
Why does capacitance decrease with age?
Because walls become more stiff and rigid
When arterial walls are more stiff, what does this do to pressure during systole and diastole?
Systole = increased pressure
Diastole = decreased pressure
What are the “resistance vessels” in the body?
Arterioles due to contraction and relaxation of their smooth muscle walls
What will happen to arteriole walls when there is a decrease in oxygen?
Vasodilate to bring in more blood flow
Where does atherosclerosis usually occur?
- Bifurcations
- Branch points
What denotes a critical stenosis?
When the vessel wall is occluded by 75% or greater
