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Blake_Physiology_Test 2 > Blake_Physio_09_overview of circulation > Flashcards

Blake_Physio_09_overview of circulation Flashcards

1
Q

systolic pressure

A

ventricular contraction ~120mmHg

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2
Q

diastolic pressure

A

ventricular filling ~80mmHg

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3
Q

What is the arterial pressure when it reaches the vena cava?

A

0mmHg

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4
Q

Systemic cappilary pressure varies from __ to__mmHg

A

35-10

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5
Q

Systolic pulmonary artery pressure = ___mmHg

A

25

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6
Q

diastolic pulmonary artery pressure = __mmHg

A

8

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7
Q

True or False: Blood pressure cuffs measure the true phasic pressure?

A

False, Phasic pressure occurs in the aorta

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8
Q

Mean arterial pressure must be time weighted because__________________

A

more time is spent in a diastole

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9
Q

What are the functional parts of circulation?

A

Arteries - transport under high pressure

Arterioles - control conduits

Capilaries - Exchange between blood and extracellular fluid

Venules- drain capilaries

Veins - return deoxy blood to heart

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10
Q

What percentage of blood is in systematic circulation? What is the distribution between: veins, arteries, systemic arterioles and capillaries, and heart and lungs

A

84%

64% veins, 13% arteries, 7% systemic arterioles and capillaries, 16% heart and lungs

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11
Q

Velocity of blood flow is measured by what formula? what are its antecedents?

A

V=F/A

V= Velocity, F= Volume, A=cross-sectional area

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12
Q

Rank the following in order from smallest to largest cross-sectional area:

Aorta, small arteries, arterioles, capilaries, venules, small veins, vena cavae

(Sum of body vessels)

A

(smallest) Aorta, Vena Cavae, Small Arteries, Arterioles, Small Veins, Venules, Capillaries (largest)

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13
Q

3 functional principles of the circulatory system

A
  1. rate of blood flow to each tissue of the body is almost always precisely controlled in relation to the tissue need.
  2. the cardiac output is controlled mainly by the sum of all the local tissue flows.
  3. Arterial pressure regulation is generally independent of either local blood flow control or cardiac output control.
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14
Q

In each tissue, _____________ monitor tissue needs. what parameters determine tissue needs?

A

microvessels

O2, nutrients, CO2 accumulation, tissue waste accumulation

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15
Q

How does the heart respond to the demands of tissues?

A

in addition to the decrease in pressure from expanding vessels, nerve signals may signal the heart to pump the required amount of blood.

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16
Q

If arterial pressure falls below 100mmHg, nervous reflexes do the following 4 things:

A
  • increase force of heart pumping
  • constrict large venous reservoirs
  • Generally constrict most of the arterioles
  • kidneys may later play an important role in pressure control.
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17
Q

Pressure gradient

A

pressure difference between two ends of a vessel

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18
Q

resistance

A

impediment of blood flow through vessel

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19
Q

Blood flow formula and antecedents:

A

F=deltaP/R

deltaP = P1-P2

F= flow in mL/min

P1 = upstream pressure

P2=pressure at end of segment

R=resistance between P1 and P2

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20
Q

Flow is ____ proportional to pressure difference, but _____ proportional to resistance

A

directly

inversely

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21
Q

Laminar blood flow (4)

A

streamline flow

steady rate

long and smooth vessel

streamlines (layers)

22
Q

Blood flows in streamlines (layers) (4)

A
  1. each layer maintains same distance from vessel wall
  2. central-most portion of teh blood stays in the center
  3. each layer slips easily past surrounding layers
  4. velocity of fluid flowing in center is greater than that of fluid flowing towards the outer edges.
23
Q

Tubulent Flow: (4 outcomes)

A
  1. Nonlayered
  2. creates murmurs
  3. more resistance than laminar
  4. eddy currents creat even more resistance
24
Q

Turbulent flow (4 causes)

A
  1. flow is too great
  2. obstruction w/in vessel
  3. sharp turns
  4. rough surfaces
25
Q

Tendency for turbulent flow changes with 4 variables

A
  1. directly to velocity
  2. directly to diameter of vessel
  3. directly to density of blood
  4. inversely to viscosity
26
Q

Laminar flow is determined by what formula? Give the formula and its antecedents.

A

Reynolds formula for Laminar Flow

Re=(v*d*rho)/eta

Re= Reynolds number=measure of teh tendency for turbulence to occur

v=mean velocity(cm/sec); d= diameter (cm); rho= density; eta=viscocity (poise) (normal~1/30poise)

27
Q

When Re rises above _____, turbulent flow will occur in some reagions of a vessel.

A

200-400

28
Q

When Re rises above ____, turbulence will occur even in a straight vessel

A

2000

29
Q

Blood pressure means_____________

Presure can be measured with _________

A

force exerted by blood against any unit area of the vessel wall

a mercurey manometer or with electronic transducers

30
Q

Resistance is__________

How is resistance measured?

A

the impediment to blood flow in a vessel

It must be indirectly calculated from blood flow and pressure (pressure/volume/time)

31
Q

3 Major variables that determine resistance:

A

vessel radius

blood viscosity

vessel length

32
Q

What is the formula for resistance? what are the antecedants?

A

R=(8*eta*l)/πr4)

R=resistance

eta = viscosity

l = lenght of vessel

r = radius of blood vessel

33
Q

cardiac output

A

the rate of blood flow through the entire circulatory system

34
Q

What is the unit of resistance for entire systemic circulation

A

PRU = peripheral resistance unit

35
Q

In conditions where vessels are strongly constricted, total peripheral resistance may rise to ____ PRU

A

4

36
Q

When vessels are greatly dilated, the resistance can fall to as little as ___ PRU

A

0.2

37
Q

Mean pulmonary arterial pressure averages ___ mmHg

Mean left atrial pressure averages _____ mmHg

=> cardiac output is normal (100mL/sec), the total pulmonary vascular resistance is _________PRU

A

16

2

= (16-2)/100 = 0.14 PRU

38
Q

Conductance

A

The measure of blood flow through a vessel for a given pressure difference.

39
Q

Conductance is usually expressed in ______

Conductance is:

A

ml/sec per mmHg

the exact reciprocal of resistance (1/R)

=> directly proportional to diameter

40
Q

a 4x increase in vessel diameter can increase the flow by as much as _______. Therefore________

A

256x

minor changes in diameter can cause a vast increase in flow.

41
Q

Poiseuille’s Law

A

A determinant of conductance which is the reciprocal of resistance.

F=(π*DeltaP*r4)/(8*eta*l)

42
Q

for blood vessels arranged in paralel, the total resistance to blood flow is expressed as________

THerefore, total resistance _________________

A

1/Rtot

Is far less than the resistance of any single blood vessel

43
Q

Total conductance for vessels arranged in parallel is ___________________________

A

the sum of the conductance of each parallel pathway

44
Q

Circulations arranged in parallel: (6)

A

brain

kidney

muscle

gastrointestinal

skin

coronary circulation

45
Q

Amputation of a limb or removal of a kidney removes a parallel circuit: therefore: (3)

A

reduces total vascular conductance

reduces total blood flow

increases total peripheral vascular resistance

46
Q

Viscosity

A

a measure of internal resistance

the greater the viscosity, the greater the resistance

47
Q

the prime determnant of blood viscosity is the _____

A

hematocrit

48
Q

The viscosity of normal blood is about ____ times as great as the viscosity of water because____

A

3x

the large numbers of suspended red cells

49
Q

Hematocrit of men and women

A

men~42

women~38

50
Q

Viscosity of whole blood at normal hematocrit

A

~3

51
Q

When hematocrit rises to 60-70

A

polycythemia

viscosity~10

52
Q

The viscosity of blood plasma alone

A

~1.5

Blake_Physiology_Test 2 (6 decks)

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