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Physiology > [2] Lecture 10- Overview Of Circulatory System > Flashcards

[2] Lecture 10- Overview Of Circulatory System Flashcards

1
Q

Systemic Arterial pressure, systolic and diastolic:

A

120 mmHg ; 80 mmHg

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2
Q

What is systemic pressure when it reaches the termination of the vena cava

A

0

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3
Q

Systemic capillary pressure:

A

35-10 mmHg

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4
Q

Pulmonary artery systolic pressure/ diastolic?

A

25 mmHg / 8 mm Hg

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5
Q

Blood pressure is:

A

Phasic

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6
Q

Why is Mean arterial pressure not an average?

A

More time is spent in diastole than systole…not an even average

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7
Q

Transport blood under high pressure

A

Arteries

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8
Q

Controls conduits of blood

A

Arterioles

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9
Q

Involved in exchange between blood and extracellular fluid

A

Capillaries

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10
Q

Blood pressure begins to drop @ what point?

A

As arteries branch into Arterioles and into capillaries-distribution of the forces

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11
Q

What percentage of blood is in the systemic circulation?

A

84%

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12
Q

What percentage of blood is in the heart and lungs?

A

16%

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13
Q

What percentage of blood is in the veins?

A

64%

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14
Q

What percentage of blood is in the arteries?

A

13%

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15
Q

What percentage of blood is in the systemic Arterioles and capillaries?

A

7%

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16
Q

What percentage of blood is in the heart?

A

7%

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17
Q

What percentage of blood is in the pulmonary circulation?

A

9%

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18
Q

Velocity of blood flow is inversely proportional to vascular cross-sectional area:

A

V= F/A

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19
Q

Norm aortic velocity:

A

33cm/s

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20
Q

Norm capillary velocity:

A

0.3 mm/s

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21
Q

Which vessel has the largest cross-sectional area?

A

CAPILLARY

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22
Q

What does it mean that capillaries have the largest cross-sectional area?

A

V =F/A

The blood flow velocity will be much slower for exchange to occur

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23
Q

3 principles that underlie all circulatory system functions:

A

1: rate of blood flow is precisely controlled r/t tissue need
2: CO is controlled by sum of all local tissue flows [w/ limits]
3: Arterial pressure regulation is generally independent of either blood flow control OR CO control

1-Flow control
2-CO control
3:Arterial pressure

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24
Q

What mainly controls Cardiac output?

A

The sum of all the local tissue flows-tissue demands

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25
Q

If the arterial pressure drops below 100 mm Hg:

A
  • Increase F of heart pumping
  • Constrict large venous reservoirs.
  • Generally constrict most of the Arterioles throughout the body
  • Kidneys may later play role
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26
Q

General underlying rule that guide 3 principles r/t circulatory system function?

A

It is Based on tissue needs/demands

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27
Q

2 main factors that control blood flow:

A

Pressure gradient: pressure difference btw 2 ends of vessel

Impediment to blood flow through the vessel [resistance]

*P gradient and resistance

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28
Q

Ohm’s law

A

Flow through a blood vessel

F= ∆P / R

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29
Q

Ohm’s law and relation to factors:

A

Directly proportional to pressure difference

Inversely proportional to resistance

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30
Q

Where can you apply poiseuille’s law? Vessel? Body?

A

You can apply to a single vessel, an organ, or an entire circuit

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31
Q

Blood flow of adult at rest:

A

5000ml/min

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32
Q

Laminar flow:

A

Streamline flow;
Flows at steady rate and in layers …vessel is long and smooth.

Not turbulent

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33
Q

Turbulent flow

A

Nonlayered flow,
Creates murmurs,
Produces more resistance than laminar flow

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34
Q

When does turbulent flow occur?

A

When flow is too great
When blood passes an obstruction or rough surface
When blood has to make sharp turn

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35
Q

When does blood flow with great resistance?

A

When eddy currents occur

36
Q

Tendency for turbulent flow increases:

A

Direct proportion to velocity of blood flow, diameter of vessel, and density of blood

Inversely proportional to viscosity of blood

37
Q

What can cause blood to be more dense?

A

higher # RBC’s

Higher density is directly proportional to increases in turbulent flow

38
Q

Which aspect of blood flow ensures laminar flow:

A

Viscosity! Allows blood to be layered

39
Q

Measure of the tendency for turbulence to occur

A

Reynolds number;

Re= (vdp) / viscosity

40
Q

Turbulent flow will occur in SOME regions of a vessel

A

200-400

41
Q

Turbulent flow will occur even in a straight vessel

A

> 2000

42
Q

_____ is The force exerted by the blood against any unit area of the vessel wall.

A

Blood pressure

43
Q

How can pressure be measured?

A

Manometers or electric transducers

44
Q

Impediment to blood flow in a vessel

Must be indirectly calculated from measurements of blood flow and pressure

A

Resistance

45
Q

Formula for resistance

A

R = (8viscosityL / πradius^4)

46
Q

Three major variables that determine resistance:

A

Vessel radius

Blood viscosity

Vessel length

47
Q

Arteries have low or high pressure drop d/t low or high resistance

A

Low pressure drop

Low resistance

48
Q

Arterioles have low or high pressure drop d/t low or high resistance

A

High pressure drop

D/t highest resistance

49
Q

The difference between systolic and diastolic pressure

A

Pulse pressure

50
Q

This is highest arterial pressure during a cardiac cycle

A

Systolic pressure

51
Q

When is systolic pressure measured? Diastolic pressure?

A

Systolic: after systole
Diastolic: during relaxation [diastole]

52
Q

The lowest arterial pressure

A

Diastolic pressure

53
Q

Range of systemic resistance:

A

0.2-4 PRU

54
Q

How to calculate Resistance:

A

Pressure difference/ CO = R

55
Q

Resistance of systemic circulation:

A

1 PRU

56
Q

Normal CO

A

100 ml/s

57
Q

Pulmonary vascular resistance:

A

0.14 PRU

58
Q

In conditions where vessels are strongly constricted, Total peripheral resistance may rise to:

A

4 PRU

59
Q

What conditions may cause the total peripheral resistance to drop significantly?

A

Vessel dilation

60
Q

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

A

Conductance

61
Q

Conductance units:

A

Ml/sec per ml Hg

62
Q

Conductance is the exact reciprocal of:

A

Resistance

63
Q

Conductance is directly proportional to:

A

Diameter

64
Q

A minor change in what causes a vast increase in blood flow?

A

Diameter

65
Q

Poiseuille’s law:

A

F = π∆Pr^4 / 8 viscosityL

66
Q

IS resistance less in series or parallel?

A

Parallel

67
Q

Why would blood vessels branch to form parallel circuits supplying blood to the many organs/tissues of the body?

A

Total resistance is far less than the resistance of any single blood vessel.

68
Q

Total conductance for vessels =

A

The sum of the conductance of each parallel pathway

69
Q

Ex of circulations in parallel:

A 
Brain
Kidney
Muscle
GI
Skin
Coronary circulation
70
Q

When you decrease Resistance:

A

You increase conductance or flow

71
Q

What effects are there to the body when limb is amputated or kidney removed?

A

This removes a parallel circuit.

  • reduces total conductance
  • reduces total blood flow
  • increases total vascular resistance
72
Q

A measure of the fluids internal resistance

A

Viscosity

73
Q

Relate viscosity and resistance

A

Greater viscosity =greater resistance

74
Q

What is the prime determinant of blood viscosity?

A

Hematocrit

75
Q

Viscosity of water is one what is norm blood?

A

3

76
Q

Average male Hct:

A

42

77
Q

Average female hct:

A

38

78
Q

Viscosity of blood at polycythemia:

A

10

79
Q

Hct rises to 60-70:

A

Polycythemia

80
Q

Viscosity of water is one. What is blood plasma?

A

1.5

81
Q

F= π∆Pr^4 / 8nl

What are directly related and what is inversely related?

A

Viscosity and l inverse

P and radius directly related

82
Q

Viscosity and anemia

A

Decreases viscosity

83
Q

Polycythemia and viscosity

A

Increases

84
Q

The ability of each tissue to adjust its vascular resistance and to maintain normal blood flow through changes in arterial pressure btw approx. 70 and 175 mm Hg

A

Blood flow autoregulation

85
Q

Not enough pressure to maintain vessel

A

Critical closing pressure

86
Q

Autoregulation occurs btw pressures of:

A

75 and 175 mm Hg

Physiology (10 decks)

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