Circulation Flashcards
(118 cards)
1
Q
what is normal arterial blood pressure
A
120mmHg (systolic)/ 80mm Hg (diastolic)
2
Q
What is the BP by the time it reaches the termination of the vena cava
A
0
3
Q
What is systemic capillary pressure
A
From 35mmHg to 10 mmHg
4
Q
What is systolic pulmonary artery pressure
A
25mm Hg
5
Q
What is diastolic pulmonary artery pressure
A
8mm Hg
6
Q
What is the function of arterioles
A
control conduits
7
Q
What is the function of capillaries
A
exchange between blood and extracellular fluid
8
Q
What percentage blood is in the systemic circulation
A
84 %
9
Q
what percent of blood is in the veins
A
64%
10
Q
What percent of blood is in the arteries
A
13%
11
Q
What percent of blood is in the systemic arterioles and capillaries
A
7%
12
Q
What percentage of blood volume is in the heart and lungs
A
16%
13
Q
What percentage of blood is in the pulmonary circulation
A
9%
14
Q
What percentage of blood is in the heart
A
7%
15
Q
The velocity of blood flow (v) is inversely proportional to what
A
vascular cross-sectional area (A)
16
Q
What is the equation for velocity of blood flow
A
V=F/A (F= volume of blood flow)
17
Q
what is the velocity of blood in the aorta when at rest
A
33cm/sec
18
Q
What is the velocity of blood at the capillaries when at rest
A
0.3mm/sec
19
Q
What is the cross-sectional area of the aorta
A
2.5cm squared
20
Q
What is the cross-sectional area of small arteries
A
20 cm squared
21
Q
What is the cross-sectional area of Arterioles
A
40 cm squared
22
Q
What is the cross-sectional area of Capillaries
A
2500cm squared
23
Q
What is the cross-sectional area of Venules
A
250 cm squared
24
Q
What is the cross-sectional area of small veins
A
80 cm squared
25
What is the cross-sectional area of Vena Cavae
9 cm squared
26
What are the three functional principles of the Circulatory system
- Rate of blood flow to each tissue of the body is almost always precisely controlled in relation to the tissue need.
- The cardiac output is controlled mainly by the sum of all local tissue flows
- Arterial pressure regulation is generally independent of either local blood flow control or cardiac output control
27
In each tissue what monitors tissue needs
Microvessels
28
O2, other nutrients, CO2 accumulation, tissue waste product accumulation at directly on what
local blood vessels and dilate or constrict accordingly
29
The heart responds to demand of _____
Tissues
30
____ may be needed to help the heart pump required amount of blood
nerve signals
31
Explain the nervous reflex if the arterial pressure falls below 100mm Hg
increase force of heart pumping
constrict large venous reservoirs
Generally constrict most of the arterioles throughout the body (increases arterial pressure)
Kidneys may later play important role in pressure control
32
What are two factors determining blood flow
Pressure gradient- pressure difference between the two ends of a vessel
Impediment to blood flow though the vessel (resistance)
33
Flow is directly proportional to _______ but inversely proportional to ______
Pressure difference, resistance
34
The flow through a vessel can be calculated by ____ (_____)
ohm's law (poiseuille equation)
35
Flow is directly proportional to what
pressure difference
36
Flow is indirectly proportional to what
Resistance
37
What is poiseuille's equation
Force= change in pressure/Resistance
38
Poiseuille's equation can be applied to.....
a single vessel, an organ, or an entire circuit
39
Blood flow is usually expressed as
ml/min or liters/min
40
The overall blood flow of an adult at rest is on average
5000 ml/min or 5 liters/min this equals the cardiac output
41
Is the cardiac output equal to the average overall blood flow of an adult at rest
Yes
42
Laminar blood flow is equal to what
streamline flow
43
laminar blood flow means that blood flows at a steady _____ and in
Rate, in layers
44
Laminar blood flow means the vessel is ___ and ___
long and smooth
45
In laminar blood flow does each layer maintain the same distance from the vessel wall
yes
46
in laminar blood flow the velocity of fluid flowing in ______ is greater than that of the fluid flowing toward _______
Center, outer edges
47
Turbulent flow creates what
Murmurs
48
Does turbulent flow form layers
No
49
Which is more resistant turbulent flow or laminar flow
Turbulent
50
When does Turbulent flow occur
when flow is too great
when blood passes an obstruction within the vessel
When blood has to make a sharp turn
When blood passes over a rough surface
51
What is Turbulent flow
When blood flows in all directions in the vessel and continually mixes within the vessel.
52
What are eddy currents
similar to the whirlpools that one frequently sees in a rapidly flowing river at a point of obstruction
When present the blood flows with much greater resistance than when the flow is streamlined, eddies add tremendously to the overall friction of flow in the vessel
53
Tendency for turbulent flow increases in direct proportion to?
Velocity of blood flow
diameter of the vessel
Density of the blood
54
Tendency for turbulent flow is inversely proportional to
Viscosity of blood
55
Is blood heavier than water
yes
56
Specific gravity of blood is
1.055
57
Blood density depends on the proportion of
its components and in particular of red blood cells and proteins
58
Is blood more viscous than water
Yes
59
The relative value of blood viscosity is what, when compared t the viscosity of water
4.5
60
Blood _______ is the property of blood to adhere to vessel walls and to each other and is based on the number, shape, and size of red cells
Viscosity
61
Viscosity ensure ______ of blood through the vessels
Laminar flow
62
What is Reynolds number
it is a measure of the tendency for turbulence to occur
63
What is the equation for Reynold's number
Re= (VxDxP)/n
| n=viscosity (in poise)
64
What is the normal blood viscosity in poise
1/30 poise
65
The density of blood is normally
only slightly greater than 1
66
When Re rises above ______, turbulent flow will occur in some regions of a vessel
200-400
67
When Re rises above _____, turbulence will occur even in a straight vessel
2000
68
Blood pressure measures
The force exerted by the blood against any unit area of the vessel wall
69
Blood pressure can be measured with
mercury manometer or with electronic transducers
70
___________ is the impediment to blood flow in a vessel
Resistance
71
Resistance must be indirectly calculated from measurements of _____ and _____
blood flow and pressure
72
Resistance equation in terms of blood
R=Pressure/volume/time
73
What is a PRU
Peripheral resistance unit
74
What are the three major variables that determine resistance
Vessel radius, Blood viscosity, Vessel Length
75
What is the most important of the 3 major variables determining resistance
vessel radius
76
R=?
R=8nl/3.14(r^4)
n= visocosity of blood
l= length of vessel
77
What vessels have the largest pressure drop
Arterioles
78
Why do arterioles have the largest pressure drop
they have the highest resistance
79
There is a low pressure drop across the major arteries due to what
they have low resistance
80
pulse pressure is the difference between ___ and ___
Systolic and diastolic pressure
81
Systolic pressure is the _____ arterial pressure duing a cardiac cycle
Highest
82
Diastolic pressure is the _____ arterial pressure
Lowest
83
Systolic pressure is measured after _____
Systole
84
Diastolic pressure is measured when
the hear is relaxed (diastole)
85
What is the Rate of blood flow though the entire circulatory system
100ml/sec
86
What is the pressure difference from systemic arteries to systemic veins
100 mm Hg
87
What is the resistance of the entire systemic circulation
Rate of blood flow/pressure difference= 100/100=
| 1 PRU
88
In conditions when the vessels are strongly constricted, total peripheral resistance may rise to ___ PRU
4
89
When vessels are greatly dilated, the resistance can fall to as little as ___ PRU
0.2
90
What is the average mean pulmonary arterial pressure
16 mm Hg
91
What is the mean left atrial pressure
Averages 2 mm Hg
92
What is the average resistance of the pulmonary system when cardiac output is the normal 100ml/sec
0.14 PRU
93
_______ is the measure of blood flow through a vessel for a given pressure difference
Conductance
94
Conductance is the exact reciprocal of what
Resistance
95
Conductance is directly proportional to what
Diameter^4
96
A fourfold increase in vessel diameter can increase the flow by as much as what
256x
97
Arterioles, with only a minor change in diameter, can cause a vast _______ in blood flow
Increase
98
Conductance is usually expressed in what
ml/sec per ml Hg
99
Blood vessels branch extensively to form ____ circuits that supply blood to the many organs and tissues of the body
Parallel
100
The total resistance of blood vessel branches is far ____ than the resistance of any single blood vessel
less
101
The total conductance of vessels arranged in parallel is the ____ of the conductance of each parallel pathway
sum
102
Name the 6 circulations arranged in parallel
```
Brain
Kidney
Muscle
Gastrointestinal
Skin
Coronary Circulation
```
103
Removal of a limb or removal of a kidney removes a parallel circuit and results in
Reduces total vascular conductance
Reduces total blood flow
Increases total peripheral vascular resistance
104
_____ is a measure of the fluid's internal resistance
Viscosity
105
The greater the viscosity, the great the
Resistance
106
What is the prime determinant of blood viscosity
Hematocrit
107
The viscosity of normal blood is about ____ times as great as the viscosity of water, mostly because of the large numbers of
3, suspended red blood cells
108
What is the normal hematocrit of adult men
42
109
What is the normal hematocrit of adult female
38
110
When the hematocrit rises to 60-70 what is this called
polycythemia
111
when the hematocrit rises to 60-70 what is the viscosity
about 10
112
What is the viscosity of blood plasma w/o RBCs
1.5 that of water
113
What effect does anemia have on viscosity
it decreases it
114
What effect does polycythemia have on viscosity
it increases it
115
Autoregulation of blood flow occurs between
changes in arterial pressure between 70 ad 175 mm Hg
116
Explain tissue blood flow autoregulation
The ability of each tissue to adjust its vascular resistance and to maintain normal blood flow through changes in arterial pressure between approximately 70 an 175 mm Hg
117
Sympathetic innnervation effects ______ and effects arterial pressure
vascular tone
118
as sympathetic stimulation increases so does
arterial pressure
