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MIDS 237 > Ch 9 Arterial Physiology > Flashcards

Ch 9 Arterial Physiology Flashcards

1
Q

What is inertia?

A

Tendency of body at rest to stay at rest
or
Tendency of body in motion to stay in motion

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2
Q

What is kinetic energy?

A

-Aka energy of work or motion
-Represented by velocity of blood flow

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3
Q

What is potential energy?

A

-Aka stored/resting energy
-It is the intravascular pressure, which distends vessels
-Pressure is supplied by the contraction of the heart

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4
Q

What is the bernoulli principle?

A

When fluid flows w/o change in velocity from 1 point to another, there is no frictional losses

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5
Q

What is ohm law?

A

Flow through 2 points is directly proportional to the potential difference across the 2 points, and inversely proportional to the resistance b/w them

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6
Q

What does capacitance mean?

A

-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

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7
Q

The total energy of a system is made up of ___ + ___ energy?

A

Potential + kinetic

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8
Q

Blood will move from an area of ___ energy/pressure to an area of ___ energy/pressure?

A

High, lower

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9
Q

The highest pressure in the vascular system occurs where?

A

LV of heart, approx 120 mm Hg

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10
Q

The lowest pressure in the vascular system occurs where?

A

RA of heart, approx 2-6 mm Hg

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11
Q

What is gravitational potential energy?

A

-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

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12
Q

When would gravitational potential energy be reduced?

A

In dependent parts of the body (below RA)

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13
Q

What is hydrostatic pressure?

A

Pressure within vessels related to the reference point of the RA

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14
Q

When would hydrostatic pressure increase?

A

Increases in the lower portions of the body, the farther below the RA = the greater it is

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15
Q

Does gravitational potential energy + hydrostatic pressure cancel each other out?

A

Yes - b/c both formulas are the same but with an opposite sign

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16
Q

In the vascular system, energy is almost all dissipated in the form of ___ b/c of friction?

A

Heat

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17
Q

How does the bernoulli principle relate to pressure?

A

High pressure = low velocity
Low pressure = high velocity

(inverse of each other)

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18
Q

What is the most important influence on blood viscosity?

A

Hematocrit (concentration of RBCs)

19
Q

Blood viscosity increases with an increase in ___?

A

Hematocrit

20
Q

When would inertial loss occur?

A

Whenever blood is forced to change direction or velocity

(depends on the density + velocity of blood flow)

21
Q

Velocity + flow are related by the following equation:

A

V = Q/A

(V = velocity, Q = blood flow, A = area)

22
Q

Does velocity go faster or slower in a more narrow orifice?

A

Faster

(velocity + area are inversely related)

23
Q

Which vessel has the largest cross-sectional area?

A

Capillaries (600x greater than the Ao, due to their large number)

(increases from Ao, arteries, arterioles, capillaries)

24
Q

Which law describes flow as “steady laminar flow”?

A

Poiseuille’s law (although flow is actually pulsatile + does not tend to move in a laminar fashion)

25
Q

What causes an increase + decrease in flow according to poiseuille’s law?

A

Increase:
-increase in pressure difference
-increase in radius

Decrease:
-increase in viscosity
-increase in vessel length

26
Q

What factor has the greatest impact on flow?

A

The radius

27
Q

Hemodynamic resistance is described by which law?

A

Ohm’s law: R = P/Q

(R = resistance, P = pressure difference, Q = flow)

28
Q

The combination of poiseuille’s law + ohm’s law creates what equation?

A

R = 8nl/3.14r^4

(n = viscosity, l = length, r = radius)

29
Q

Changes in resistance is virtually all because of variations in ___?

A

Radius

30
Q

List the formula for resistance in series?

A

Rt = R1 + R2 + R3

31
Q

List the formula for resistance in parallel?

A

1/Rt = 1/R1 + 1/R2 + 1/R3

(the more parallel = the lower the overall resistance)

32
Q

Low resistance flow profiles have what type of flow?

A

Antegrade - feeds regions with constant high demand (ex. the brain)

(ICA, vertebral, celiac, splenic, hepatic + renal arteries)

33
Q

High resistance flow profiles have what type of flow?

A

Antegrade + retrograde - does not feed regions with constant high demand (ex. face)

(ECA, subclavian, distal Ao, iliac, fasting superior mesenteric + resting peripheral arteries)

34
Q

When would high resistance tissue beds change into low resistance beds?

A

-With extremity arteries after exercise
-With the SMA after eating

35
Q

Turbulent flow is defined by ___ number?

A

Reynolds number

Re < 2000 = laminar
Re > 2000 = turbulent

36
Q

What is hydraulic filtering?

A

It converts pulsatile output of the heart to a steady flow through the capillaries via elastic conduits + high resistance terminals

37
Q

Capacitance increases or decreases with age?

A

Decreases b/c walls get rigid

(greater pressure during systole, reduced pressure during diastole)

38
Q

Atherosclerotic changes begin with what?

A

A lipid streak that consists of subintimal deposits of fat

39
Q

SF of fibrous + complicated plaque?

A

Fibrous:
-smooth surface
-composed of smooth muscle + fibrous tissue
-no calcification

Complicated:
-irregular surface
-loss of normal endothelium
-calcifications

40
Q

What 2 spots does atherosclerosis typically develop in?

A

Branch points + bifurcations

41
Q

Define what a critical hemodynamically significant stenosis is?

A

-A degree of narrowing at which pressure + flow are affected
-When cross sectional area is reduced by 75%

42
Q

Is stenosis in a low or high resistance system more critical?

A

Low resistance systems (ex. carotid arteries) can become more critical with a less severe degree of narrowing compared to low flow/high resistance systems (ex. leg arteries)

43
Q

What are collateral vessels?

A

-Pre-existing pathways that enlarge with a stenosis or occlusion
-A main mechanism to compensate for stenosis

44
Q

Collateral arteries can be divided into what 3 categories?

A

-Stem arteries (large branches)

-Midzone collaterals (small intramuscular branches)

-Reentry arteries (vessels that rejoin a major artery, distal to the area of stenosis/occlusion)

MIDS 237 (23 decks)

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