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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
If the arterial pressure drops below 100 mm Hg:
- Increase F of heart pumping - Constrict large venous reservoirs. - Generally constrict most of the Arterioles throughout the body - Kidneys may later play role
26
General underlying rule that guide 3 principles r/t circulatory system function?
It is Based on tissue needs/demands
27
2 main factors that control blood flow:
Pressure gradient: pressure difference btw 2 ends of vessel Impediment to blood flow through the vessel [resistance] *P gradient and resistance
28
Ohm's law
Flow through a blood vessel F= ∆P / R
29
Ohm's law and relation to factors:
Directly proportional to pressure difference Inversely proportional to resistance
30
Where can you apply poiseuille's law? Vessel? Body?
You can apply to a single vessel, an organ, or an entire circuit
31
Blood flow of adult at rest:
5000ml/min
32
Laminar flow:
Streamline flow; Flows at steady rate and in layers ...vessel is long and smooth. Not turbulent
33
Turbulent flow
Nonlayered flow, Creates murmurs, Produces more resistance than laminar flow
34
When does turbulent flow occur?
When flow is too great When blood passes an obstruction or rough surface When blood has to make sharp turn
35
When does blood flow with great resistance?
When eddy currents occur
36
Tendency for turbulent flow increases:
Direct proportion to velocity of blood flow, diameter of vessel, and density of blood Inversely proportional to viscosity of blood
37
What can cause blood to be more dense?
higher # RBC's Higher density is directly proportional to increases in turbulent flow
38
Which aspect of blood flow ensures laminar flow:
Viscosity! Allows blood to be layered
39
Measure of the tendency for turbulence to occur
Reynolds number; | Re= (vdp) / viscosity
40
Turbulent flow will occur in SOME regions of a vessel
200-400
41
Turbulent flow will occur even in a straight vessel
>2000
42
_____ is The force exerted by the blood against any unit area of the vessel wall.
Blood pressure
43
How can pressure be measured?
Manometers or electric transducers
44
Impediment to blood flow in a vessel Must be indirectly calculated from measurements of blood flow and pressure
Resistance
45
Formula for resistance
R = (8viscosityL / πradius^4)
46
Three major variables that determine resistance:
Vessel radius Blood viscosity Vessel length
47
Arteries have low or high pressure drop d/t low or high resistance
Low pressure drop Low resistance
48
Arterioles have low or high pressure drop d/t low or high resistance
High pressure drop D/t highest resistance
49
The difference between systolic and diastolic pressure
Pulse pressure
50
This is highest arterial pressure during a cardiac cycle
Systolic pressure
51
When is systolic pressure measured? Diastolic pressure?
Systolic: after systole Diastolic: during relaxation [diastole]
52
The lowest arterial pressure
Diastolic pressure
53
Range of systemic resistance:
0.2-4 PRU
54
How to calculate Resistance:
Pressure difference/ CO = R
55
Resistance of systemic circulation:
1 PRU
56
Normal CO
100 ml/s
57
Pulmonary vascular resistance:
0.14 PRU
58
In conditions where vessels are strongly constricted, Total peripheral resistance may rise to:
4 PRU
59
What conditions may cause the total peripheral resistance to drop significantly?
Vessel dilation
60
The measure of blood flow through a vessel for a given pressure difference
Conductance
61
Conductance units:
Ml/sec per ml Hg
62
Conductance is the exact reciprocal of:
Resistance
63
Conductance is directly proportional to:
Diameter
64
A minor change in what causes a vast increase in blood flow?
Diameter
65
Poiseuille's law:
F = π∆Pr^4 / 8 viscosityL
66
IS resistance less in series or parallel?
Parallel
67
Why would blood vessels branch to form parallel circuits supplying blood to the many organs/tissues of the body?
Total resistance is far less than the resistance of any single blood vessel.
68
Total conductance for vessels =
The sum of the conductance of each parallel pathway
69
Ex of circulations in parallel:
``` Brain Kidney Muscle GI Skin Coronary circulation ```
70
When you decrease Resistance:
You increase conductance or flow
71
What effects are there to the body when limb is amputated or kidney removed?
This removes a parallel circuit. - reduces total conductance - reduces total blood flow - increases total vascular resistance
72
A measure of the fluids internal resistance
Viscosity
73
Relate viscosity and resistance
Greater viscosity =greater resistance
74
What is the prime determinant of blood viscosity?
Hematocrit
75
Viscosity of water is one what is norm blood?
3
76
Average male Hct:
42
77
Average female hct:
38
78
Viscosity of blood at polycythemia:
10
79
Hct rises to 60-70:
Polycythemia
80
Viscosity of water is one. What is blood plasma?
1.5
81
F= π∆Pr^4 / 8nl | What are directly related and what is inversely related?
Viscosity and l inverse P and radius directly related
82
Viscosity and anemia
Decreases viscosity
83
Polycythemia and viscosity
Increases
84
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
Blood flow autoregulation
85
Not enough pressure to maintain vessel
Critical closing pressure
86
Autoregulation occurs btw pressures of:
75 and 175 mm Hg

Physiology (10 decks)

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