Cardiovascular Hemodynamics 1C2 Flashcards
1
Q
what do arteries do
A
blood from heart to organs
2
Q
what are arterioles
A
smaller arteries of the organs receiving blood supply
3
Q
what are capillaries and what exchanges happen
A
smaller vessels where exchange between blood and organs occur
4
Q
where do venules carry blood from
A
carry blood from the organs
5
Q
what are veins
A
veins are convergence of venues to return blood to the heart
6
Q
what are big differences between artery and veins
A
veins and arteries have about the same amount of endothelium and fibrous tissues
arteries have a more elastic tissue and smooth muscle then veins
7
Q
arteries carry blood ____ from the heart
A
away
8
Q
pulmonary arteries carry what
A
carry deoxygenated blood from right ventricle to the pulmonary circulation
9
Q
what does the aorta do
A
pumps oxygenated blood from the left ventricle to the systemic circulation
10
Q
veins carry blood to the
A
heart
11
Q
what drains into the right atrium
A
SVC, IVC, coronary sinus drains deoxygenated blood from the systemic circulation
12
Q
what drains into the left atrium
A
right and left pulmonary veins drains oxygenated blood from pulmonary circulation
13
Q
blood flow of the heart is
A
unidirectional
14
Q
one way valves will not open in ______ direction
A
opposite direction
15
Q
greater pressure behind the valve causes the valve to
A
open
16
Q
greater pressure in from the valve causes the valve to
A
close
17
Q
what are the valves
A
mitral
tricuspid
aortic
pulmonary
18
Q
what is the windkessel effect
A
large arteries expand, absorb pressure wave then release it with elastic recoil
-helps push the blood down the legs/ to the rest of the body
19
Q
what help to push blood along during diastole
A
elastic arteries
20
Q
what can the aorta and elastic arteries change
A
can vasoconstrictor or vasodilator
21
Q
with aging, what do we have less of when it comes to elastic arteries
A
less expansion and recoil
22
Q
Elastic recoil of ____ propels blood along
A
artery
23
Q
what enables the arteries to expand
A
great amount of elastin
24
Q
in terms of elastic recoil, what happens when the heart relaxes
A
the recoil propels blood onward
25
what do the contraction of skeletal muscles in the leg assists with
assists with venous return from the legs
26
how does the blood vessels in the leg move blood forward (and against gravity) back toward the heart
- veins in the legs are guarded by valves to prevent back flow of the blood
- contraction provides an extravascular compression on these blood vessels which moves the blood forward
27
what aids in keeping the airways of the lungs open
the slight negative pressure that is in the thoracic cavity
28
what helps assists with venous return to the right side of the heart
the contraction of the diaphragm and intercostal muscles in the thoracic cavity
29
what causes the contraction in the thoracic cavity to help with the venous return to the heart
- each time a person inhales, there is a slight drop in internal thoracic pressure
- this creates a pressure gradient which assists in the flow of venous blood moving forward (against gravity) and back toward the heart
30
what are the principles of Boyle's law
pressure and volume have an inverse relationship
31
equation for Boyle's Law
P1 x V1 = P2 x V2
32
during quiet inspiration, the lung volume ____ and the pressure in the lungs ______
the lung volume increases and the pressure in the lungs decrease
33
Hemodynamics definition
physical factors that govern blood flow
34
Ohm's Law
current (I) equals the voltage difference (delta V) divided by resistance (r)
35
Ohm's Law to fluid flow
F = delta P / R
- the voltage difference is the pressure difference
- the resistance is the resistance to flow (R) offered by the blood vessel and its interactions with the flowing blood
- the current is the blood flow (F)
36
regarding Ohm's law to fluid flow and for the flow of blood in a blood vessel the delta P is what
the pressure difference between any two points along a given length of the vessel
37
what is the formula for the flow of blood in a blood vessel
F = delta P / R = (Pa - Pv) / R
- Pa is arterial pressure
- Pv is venous pressure
38
when talking about blood flow across a heart valve, what is the equation>
F = (Piv - Pao) / R
- Piv is the intraventricular pressure
- Pao is the aortic pressure
- R is resistance
39
what is the pressure that drives flow across the aortic valve during ventricular ejection
intraventricular pressure
40
what is the resistance to flow related to
related in large part to the size of the valve opening
41
what is blood flow
mass of substance that passes a certain point in one minute
42
in perfusion, what is blood flow measured in?
mL/min or L/min
43
blood flow is dependent on _____ and _____
pressure gradient and resistance
44
definition of pressure gradient
difference in pressure b/w the beginning and end of the vessel
45
Blood flow from and area of ___ to an area of ____
high pressure to an area of low pressure
46
when does the heart create high pressure
when it contracts
47
why does pressure drop along the length of a blood vessel
due to frictional losses between the fluid and blood vessel walls
48
where is the high pressure in the vessels of the cardiovascular system?
aorta
49
where is the lowest pressure in the vessels of the cardiovascular system?
right atrium
50
flow and resistance are _____ related
reciprocally
51
an increase in resistance _____ flow at any given ___
an increase in resistance decreases flow at any given delta P
52
at any given flow along a blood vessel or across a heart valve, an ___ in resistance ____ the delta P
an increase in resistance increases the delta P
53
During ____ flow conditions, there is a ___ and _____ relationship between flow and perfusion pressure
During laminar flow conditions, there is a linear and proportionate relationship between flow and perfusion pressure
54
what does turbulence cause
decrease the flow at any given perfusion pressure
55
what causes an increase in resistance to flow and thus a decrease flow
pulsatility in blood pressure
56
an increase in delta P does what to the flow
increase in flow
57
what does flow require
a pressure gradient
58
the higher the pressure gradient = ______ = _____
the higher the pressure gradient = the greater pressure gradient = the higher the flow
59
flow always follows the path of
least resistance
60
as blood vessels get small....
the flow is decreased
61
small amounts of ___ ____ can have dramatic effects
small amounts of arterial occlusion can have dramatic effects
62
small vessels are the dominant contributors to ___ _____
flow resistance
63
__ _____ is accomplished by vasodilation and vasconstriction in the arterioles
flow regulation is accomplished by vasodilation and vasoconstriction in the arterioles
64
what does Poiseuille's law describe
smooth flow conditions
| if you change one, it'll have an effect on the others
65
a 19% increase in radius will do what to the volume flow rate
will double the volume flow rate
66
In terms of Poiseuille's law, what will have the biggest effect on flow rate
increasing the radius
67
Suppose the original flow rate is 100 cm3/sec. the effect of doubling the length changes the flow rate to
50 cm3/sec
68
Suppose the original flow rate is 100 cm3/sec. the effect of doubling the viscosity changes the flow rate to
50 cm3/sec
69
Suppose the original flow rate is 100 cm3/sec. the effect of doubling the pressure changes the flow rate to
200 cm3/sec
70
Suppose the original flow rate is 100 cm3/sec. the effect of doubling the radius changes the flow rate to
1600 cm3/sec
71
Suppose you have an emergency requirement for a five-fold increase in blood volume rate (like being chased by a big dog), does your body supply it?
- arterioles in their position just prior to the capillaries provide major control on volume flow rate
- small vessels can constrict flow to one part of the body while enhancing flow to another to meet changing demands of oxygen and nutrients
72
How occluded does arteries have to be before bypass surgery can happen?
70%
73
definition of resistance
opposition to blood flow due to friction between the fluid and vessel walls
74
what are 4 factors that determine resistance
- vessel radius
- vessel length
- viscocity
- turbulent flow
75
increased radius =
decrease resistance
76
increased length =
increased resistance
77
increased viscocity (n) =
greater resistance
78
vasoconstriction causes ____ in radius and ____ in resistance
decrease in the radius and increases in resistance
79
vasodilation causes ____ in radius and ____ in resistance
increase in the radius and decreases in resistance
80
what is the most important factor of resistance
changes in vessel radius
-alters resistance to the fourth power of the change in radius
81
if the radius of a blood vessel doubles (by vasodilation) then the Flo will
increase 16 fold
82
if the radius of a vessel is reduced in half (by vasoconstriction) then the blood will
be reduced 16 fold
83
what does small diameter arterioles cause
major determinant of peripheral vascular resistance (PVR)
84
what does fatty plaques from atherosclerosis cause
cause turbulent flow and dramatically increase resistance due to turbulence
85
delta P = 100 mmHg
normal CO is 5 l/min
total PVR is 20 mmHg*min/L
assuming constant pressure differences, which resistance value will raise the blood flow to 25 L/min?
r = 4
86
high arteriolar resistance causes a mark drop in
MAP
87
what are considered major resistance vessels
arterioles
88
what makes the arterioles a major resistance vessels
the radius is small enough and can be adjust to variable distribute cardiac output among the tissue organs
89
resistance converts the pulsatile nature of systolic-diastolic pressure to
non-pulsatile pressure within the capillaries
90
smooth muscle of the small arterioles is contracted by
sympathetic nerves
91
the _______ respond to local factors
precapillary sphincters
92
does exchange happen in metarterioles?
no
93
what do metarterioles serve as
- serve as thoroughfare channels, which bypass the capillary bed
- or conduits to supply the capillary bed
94
what is the neurogenic stimulator for vasoconstrictor
enothelin-1
95
what is the neurogenic stimulus for vasodilater
nitric oxide
96
vascular tone is normally in a state of slight ____
constriction
97
what does vascular tone establish and enable?
- establishes baseline arteriolar resistance
| - enables vasoconstriction and dilation
98
what is myogenic activity of smooth muscle and what is it responsive to
- self induced contractile activity
| - responsive to neural and hormonal mediators
99
___ is released continuously by sympathetic fibers of ANS
NE
100
what reduces blood flow through an arteriole and redirects the flow through all arterioles with a lower resistance?
arteriolar constriction
101
total blood flow through all the arterioles of the body always equals what.?
cardiac output
102
local control of arteriolar diameter is by _____, secreted by the _____ or by _____ which the arterioles are supply blood
diameter is by paracrines, secreted by the vascular endothelium or by tissues to which the arterioles are supplying blood
103
in terms of local control, low O2 and high CO2 ____ arterioles which ____ blood flow into the tissues
dilate arterioles which increase
104
systemic control of arteriolar diameter is by
sympathetic innervation
-release of NE, which then binds on vascular smooth muscle
105
if sympathetic release of NE decreases, what happens to the arterioles
they dilate
106
if the release of norepinephrine increases, what happens to arterioles
constrict
107
what is the major role of arterioles
to constrict or dilate to control the resistance of blood flow in the body as a whole
108
what is the center in the brainstem that regulates SVR or total peripheral resistance?
vasomotor center
109
what are the neuroreceptors that cause constriction or dilation in the arterioles
constriction = a1
dilation = b2
110
laminar flow is what kind of direction
uniform direction
| blood moving in a parallel downtown he length of blood vessel
111
turbulent flow iswwhat kind of direction
chaotic flow
112
where does turbulent flow usually happen
usually occur across a valve
113
what two things does turbulent flow increase?
- increases energy required to drive blood flow b/c increases friction
- increases perfusion pressure required to drive a given flow
114
what kind of flow is in capillaries and why?
always laminar flow
| b/c of smaller radius and lowest velocity
115
what does Reynolds number predict
when turbulence will occur, under ideal conditions
116
Reynolds number equation
Re = (v * D * p) / n
```
v = mean velocity
D = vessel diameter
p = blood density
n = blood viscosity
```
117
Laminar flow = numbers up to _____
2000
118
turbulent flow = numbers greater than ____
4000
119
what are the numbers for transition b/w laminar and turbulent flow
b/w 2000-4000
120
flow equation
flow = pressure / resistance
121
CO =
| when applied to circulatory system
CO = (MAP - RAP) / TPR
122
what is CO measured in
L/min
123
what is MAP and what does it measure
mean arterial pressure (mmHg)
| the average pressure of blood as it leaves the heart
124
what is RAP and what does it measure
right atrial pressure (mmHg)
| average pressure of blood as it returns to the heart
125
what is total TPR
total peripheral resistance (in mmHg*min/L)
126
capacitance of blood vessels means what
the ability of a vessel to distend and increase volume with increasing transmural pressure
127
equation for capacitance
C = delta V / delta P
change in volume divided by change in pressure
128
compliance _____ at higher pressure and volumes
decreases at high pressures and volumes
129
at lower pressure, the compliance of a vein is about ___ to ___ times greater than an artery
10 to 20
130
____ can accommodate a LARGE change in blood volume with only a small change in pressure
veins
131
which has high compliance, veins or arteries
veins
132
equation for MAP
diastolic pressure + (1/3) x pulse pressure
133
when do pulse pressure and MAP decline
increasing distance from the heart
134
what kind of relationship do velocity of blood flow and total cross-sectional are of blood vessels have?
incerse
135
the greater the cross sectional area, the ____ the blood flow
slower
136
blood flow velocity is _____ in the middle of the vessel and _____ at the vessel wall
is fastest in the middle of the vessel and slowest at the vessel wall
137
equation for CI
Sv/BSA x HR
138
how many modulators are involved in maintaining adequate supply of oxygen to all tissues under all metabolic conditions
4
139
what are the four hemodynamic modulators
1. intravascular volume
2. inotropy
3. vasoactivity
4. chronotropy
140
what are some volume reducing drugs (diuretics)
volume expanders
blood plasma
albumin
141
vasodilators
hydralazine
nitric oxide
sodium nitroprusside
142
vasoconstrictors
phenylephrine
methoxamine
vasopressin
ADH
143
what do baroreceptor reflexes change
peripheral resistance, heart rate, and stroke volume in response to changes in bp
144
what are chemoreceptor reflexes sensitive to
lack of oxygen, CO2 excess, low pH levels of blood
145
central nervous system ischemic response is a result from
severe decrease blood flow to the brain
146
where are baroreceptors found
- carotid sinuses by glossopharyngeal nerve
| - aortic arch by vagus nerve
147
the heart is controlled by what cardiac centers
medulla oblongata and innervated by the autonomic nervous system
148
where does the parasympathetic neuron come from and where does it synapse
from cardioinhibitory center and synapses in the dorsal Motor nucleus of the medulla
149
what sends parasympathetic impulse to theSA and AV node
vagus
150
when the CIC activity increases by stimulating the vagus nerve, this causes
decrease HR
| decrease SV
151
where does the sympathetic neuron come from and where does it synapse
from cardioacceletory center and synapses at thoracic spinal cord
152
what sends sympathetic impulse to theSA and AV node
postgangloionic fibers
153
when the CAC activity decreases and inhibits sympathetic nerves, this causes
decreases in CO
154
short term regulation of falling blood pressure
- baroreceptors inhibited
- decreased impulse to the brain
- decreased parasympathetic activity and increased sym activity
- cause an increase in HR, contractility, and vasoconstriction
- then cause an increase in bp
155
short term regulation of rising bp
- rising blood pressure
- stretching of arterial walls
- stimulation of baroreceptors in carotid sinus, aortic arch, and other large arteries of neck and thorax
- increased impulses to the brain
156
where are the peripheral chemoreceptors and what do they detect
- located in the carotid body and aortic body
| - detect large changes in pO2
157
if an abnormal low pO2 is detected, what happens to increase it again?
- impulse travel to respiratory centers
- increasing respiratory rate
- direct blood flow towards kidneys and brain
- increase CO in order to maintain blood flow
158
where are the central chemoreceptors and what are they sensitive to
- located in the medulla oblongata of the brainstem
| - more sensitive and detect smaller changes in arterial pCO2 and changes in pH of CSF
159
the pH of the CSF is approx ____ proportional to the arterial pCO2
inversely proportional
160
a small drop in pCO2 leads to what
an increase in pH of CSF
- stilmulates decrease in ventilation
- this results in more CO2 being retained in lungs
161
if pCO2 levels stay abnormal for 3 or more days, what happens
- choroid plexus cells allow HCO2 ions to enter the CSF
| - this can reset to a different pCO2 by manipulating the pH
162
when there's a loss of blood
BP and blood volume decrease
163
long term regulation of BP is done by
the kidneys
164
principle hormone involved in long term regulation of BP by kidneys
ADH
aldosterone
renin-angiotensin system
ANP
165
what are the capillary types
continuous
fenestrated
sinusoidal
166
continuous capillary type
most common
| endothelial cels are joined by leaky junctions
167
where are continuous capillary found
skeletal muscle
blood brain barrier
skin
168
sinusoidal capillary type
open pore capillary
| aka discontinuous capillary
169
where is sinusoidal capillaries found
spleen and liver
170
fenestrated capillary type
endothelial cells have large pores that allow high volume to pass quickly b/w the plasma and interstitial fluid
171
where are fenestrated capillaries found
endocrine glands, intestines, pancreas, and the kidney
172
what is bulk flow
solutes can move by diffusion as a result of hydrostatic and/or osmotic pressure gradients across capillary wall
173
filtration
bulk of flow is out of the capillary
174
reabsorption
bulk flow is into the capillary
175
transcellular exchange
non polar gasses and solutes can move by diffusion through the cell membrane of endothelial cells
-large polar solutes can move by vesicular transport
176
pinocytosis
method by which a cell absorbs small particles outside the cell and brings them inside
177
when and where does pinocytosis
- usually used for taking in extracellular fluid (ECF)
| - happens in the tissues
178
what side of the capillary has a high capillary hydrostatic pressure and lower capillary osmotic pressure?
arterial side
179
what is the pressure like in the venous side of the capillary?
lower hydrostatic pressure
| higher capillary osmotic pressure
180
filtration happens at the ____ end and absorption happens at the _____ end
filtration happens at the arterial end and absorption happens at the venous end
181
diffusion depends on ____ and bulk flow depends on ______
diffusion depends on concentration gradient and bulk flow depends on pressure
182
is it true that nearly as much fluid is reabsorbed as was filtered
yes
183
___ of the fluid that was filtered id then reabsorbed
85%
184
why does not 100% fluid return
bc a few plasma proteins leave vessels into interstitial space
185
remainder of fluid and proteins enter ___ ____ and is eventually returned to blood
enter lymphatic capillaries and is eventually returned to blood
186
the change in set driving pressure is caused by
a decrease in the capillary hydrostatic pressure along the length of the capillary
187
what two things cause swelling
1. excess filtration out of capillaries
| 2. decreased reabsorption of fluid and solutes from extracellular fluid
188
what 4 things cause edema
1. increase filtration out of vessel
2. decreased absorption back into vessel;s
3. increased membrane permeability: leaky
4. increased interstitial colloid pressure pulls fluid out of vessels
