Circulation, Hemodynamics Flashcards
(107 cards)
1
Q
Smaller vessels that go from arteries to organs
A
Arterioles
2
Q
Small vessels that go from arterioles and drain into venules
A
Capillaries
3
Q
Place where all exchange between blood and tissue occurs
A
Capillary beds
4
Q
Small vessels that drain from capillary beds into larger veins
A
Venules
5
Q
How is flow measured?
A
Liters/min
6
Q
Pressure gradient/resistance
A
= flow
7
Q
If pressure is high, flow is…
A
Faster
8
Q
If resistance is high, flow is
A
Slower
9
Q
2 things that influence vascular resistance
A
1) blood viscosity
2) radius of vessel
10
Q
What causes high viscosity in blood
A
High hematocrit (high level of RBCs)
11
Q
The smaller the radius of a vessel the __________ the resistance
A
Higher
12
Q
If radius of vessel 1 is X and vessel 2 is 2X, how much more is flow of vessel 2?
A
16 times
13
Q
What determines distribution of blood
A
Metabolic demand
14
Q
True/False: we have a finite volume of blood
A
True
15
Q
Vessels with large elaborate walls
A
Arteries
16
Q
2 functions of arteries
A
1) fast transportation of blood from heart to tissue
2) store pressure for flow when heart at rest
17
Q
5 parts of arterial wall
A
1) endothelial cells
2) connective tissue (collagen/elastin)
3) smooth muscle
4) sympathetic nerves
5) external connective tissue with tiny vessels
18
Q
What is force of blood against arterial wall?
A
Arterial BP
19
Q
What is systolic pressure
A
Ventricular contraction
20
Q
What is diastolic pressure
A
Resting pressure in arteries (ventricular diastole)
21
Q
2 purposes of reading arterial BP
A
1) health of vessel walls
2) blood volume
22
Q
What is Pulse Pressure
A
Systolic - Diastolic
23
Q
How do you calculate MAP
A
diastolic + 1/3 pulse pressure (sys - dias)
24
Q
What is the average BP at all times called?
A
Mean Arterial Pressure (MAP)
25
True/False: MAP is not a straightforward measure
True
26
What are taps heard during BP cuff reading called
Korotkoff sounds
27
If you drop BP cuff pressure too fast, what happens?
Underestimated Systolic
28
What is made of mostly endothelium wrapped in smooth muscle
Arterioles
29
Is the diameter of an arteriole changeable?
Yes
30
What vessel is the “Gatekeeper to organs”
Arterioles
31
2 main functions of Arterioles
1) distribute blood based on metabolic demands
2) regulate arterial BP
32
What is a change in arteriole diameter by constricting or dilating called
Arteriole tone
33
How is normal arteriole tone determined (4 factors)
1) elasticity
2) sympathetic input
3) hormones
4) blood volume
34
Vasoconstriction does what to flow?
Decreases
35
What does vasodilation do to flow?
Increases
36
2 general categories that cause vasoconstriction or vasodilation
1) intrinsic
2) extrinsic
37
What causes intrinsic changes in vasodilation or vasoconstriction
Local factors
38
What is meant by “local factors”
A change in the tissue
39
2 subcategories of local control
1) chemical
2) physical
40
What is the most important local chemical change that is based on organ workload
Local metabolic change
41
What causes another local chemical change in arterioles
Histamine release
42
2 causes of local physical control to arterioles
1) heat/cold (local application)
2) myogenic response to stretch
43
During local metabolic change in arterioles, what senses change in O2, CO2, acidity, Adenosine
Endothelial cells
44
What do endothelial cells release in response to a metabolic change in arterioles
1) Endothelin
2) nitric oxide
45
What does endothelin do in vessel?
Constricts (conserves blood)
46
What does nitric oxide do?
Dilated to increase blood flow
47
What is the most important extrinsic control of arterioles
Sympathetic effect
48
If sympathetic effect is increased, what happens to arterioles
General Vasoconstriction
49
If sympathetic is decreased, what happens
Vasodilation
50
Sympathetic nerve fibers supply areteriole smooth muscle everywhere except where?
The brain
51
What is TPR
Total peripheral (vascular) resistance
52
What influences TPR the most?
Arteriole diameter
53
MAP is like __________ pressure in a pipe
Constant
54
If MAP is constant pressure in a pipe, what act as spigots to change resistance?
Arterioles
55
What does epinephrine do to arteriole?
Dilates
56
What does norepinephrine do to arterioles?
Constricts
57
What do vasopressin and angiotensin 2 do?
Constrict
58
What gets majority of blood distribution when at rest?
Digestive and liver (27%)
59
What gets majority of blood distribution with moderate exercise
Skeletal muscle and heart
60
During exercise, sympathetic vasoconstricts everywhere except where?
Skeletal muscle and heart
61
If tissue mass increases, what happens to capillary density
It will increase too
62
What is velocity of blood in capillaries
Slow
63
True/false: decrease in velocity of capillary does not change flow rate
True
64
What is capillary made of
Endothelial cells
65
Is a capillary diameter slightly less or more than the diameter of a RBC?
Less
66
What moves freely through capillary pores?
1) fluid and small h2o soluble substances
2) polar substances (electrolytes)
3) lipid soluble proteins
67
What can’t get through capillary pores?
Plasma protein (albumen) and rbc/wbc
68
What do large water soluble substances need to pass thru capillary pores?
Active transport via vesicles
69
What flows to low concentration gradients in capillaries
O2 in tissue
CO2 out of tissue
NA, K, glucose
70
What sit between arterioles and venules
Capillary beds
71
What are slightly larger than capillaries
Metarterioles
72
What acts as a freeway between arterioles to venules
Metarterioles
73
What controls blood flow through capillary beds
Pre capillary sphincters
74
If pre capillary sphincters are contracted, where does blood flow
Metarterioles
75
If pre capillary sphincters are relaxed, where does blood flow
Capillaries
76
What controls the contraction or relaxation of the precapillary sphincters?
Metabolic needs
77
If there’s a high metabolic need, what does the precapillary sphincter do?
Relaxes and delivers O2, etc to tissue
78
What kind of process is distribution of fluid across capillaries
Passive
79
What distributes ECF between vascular compartment and interstitial compartment
Capillary bulk flow
80
What can capillary bulk flow buffer in a small way
Blood pressure
81
Hydrostatic
Pushes
82
Oncotic
Pulls
83
What does capillary hydrostatic BP favor?
Filtration
84
If blood volume is low and BP is low, what will capillary BP do?
Reabsorb
85
What are 2 constant passive pressures that reabsorb?
Capillary Oncotic
Interstitial hydrostatic
86
Pulls fluid into capillary
Capillary Oncotic
87
Pushes against capillary wall from outside
Interstitial hydrostatic
88
What would only happen if albumen leaked outside of capillary wall and pull fluid to interstitial space?
Interstitial Oncotic
89
If BP and blood volume is high, what would capillary BP do
Ultrafiltration
90
Large vessels with endothelial lining and very little smooth muscle
Veins
91
What are also called Blood Reservoirs or Capacitance Vessels?
Veins
92
At rest, what % of systemic blood volume is in systemic veins?
64%
93
During time of stress (exercise) what do veins do to send systemic blood volume to heart
Constrict
94
Venous return from vasoconstriction pushes blood to the heart which does what to End Diastolic Volume and Stroke Volume?
Increases
95
What is the volume of blood the veins can accommodate?
Venous capacity
96
What is the volume of blood entering each atrium from venous vessels
Venous return
97
What in veins prevents backflow
Valves
98
What are 3 “push” factors that influence venous blood return?
1) sympathetic vasoconstriction
2) muscles
3) valves
99
What are 2 “pull” factors that influence venous return to heart?
1) less thoracic pressure
2) cardiac suction
100
Measurement that tells amount of resistance in arteries
TPR
101
what affects TPR
1) blood viscosity
2) arterial radius
102
Short term control of MAP
1) Baroreceptor reflex (HR)
2) sympathetic/parasympathetic (TPR)
103
Where are baroreceptors found
Aortic arch
Carotid sinus
104
What do baroreceptors do
Measure stretch on artery wall
105
T/F: Baroreceptors are only good for a few minutes
True
106
What extrinsic influences arterial radius
Epi and vasopressin
107
What is long term control of MAP
Kidneys. Regulates fluid/plasma
