Final Exam Review Flashcards
(427 cards)
1
Q
What are the 2 pumps of the heart?
A
RV & LV
2
Q
Right ventricle = ___ circulation
A
Pulmonary circulation
3
Q
Left ventricle = ___ circulation
A
Systemic circulation
4
Q
___ causes unidirectional flow in the heart
A
Valves
5
Q
What part of the systemic circulation has the greatest resistance to blood flow?
A
Arterioles
6
Q
What is the primary function of the veins?
A
Capacitance function (has the greatest percentage of blood volume)
7
Q
___ of the aorta and its branches during systole
A
Distention
8
Q
___ of the large arteries with ___ of blood during ventricular relaxation during diastole
A
Elastic recoil of the large arteries; forward propulsion of blood
9
Q
Blood flow is essentially ___ at the capillary level
A
Non-pulsatile
10
Q
Velocity of blood flow is ___ related to the cross-sectional area of the vascular system
A
Inversely
I.e.: blood flow velocity is very slow in the capillaries (large cross-sectional area), which makes conditions ideal for exchange of diffusible substances
11
Q
The blood flow to each tissue of the body is almost always precisely controlled in relation to ___
A
Tissue needs
12
Q
Cardiac output is controlled mainly by the sum of ___
A
All the local tissue flows
13
Q
Sympathetic innervation of the heart
A
T1-T4 “cardiac accelerators”
Distributed throughout the heart
14
Q
Parasympathetic innervation of the heart originates in the ___
A
Medulla oblongata, vagus nerves
15
Q
Parasympathetic provides much innervation to ___ and little innervation to ___
A
Much innervation to SA/AV nodes; little innervation to ventricles
16
Q
What is the conduction system of the heart?
A
SA node —> AV node —> Bundle of His —> Bundle Branches (right and left)
17
Q
Interatrial conduction pathways
A
SA to LA
18
Q
Internodal conduction pathways
A
SA to AV
19
Q
Where is the AV node located?
A
On the RIGHT side of the interatrial septum, near the ostium of the coronary sinus
20
Q
Where does venous drainage of the heart occur?
A
Coronary sinus
21
Q
What are the coronary arteries (identify 2 main ones and their branches)?
A
- Right coronary
- Left coronary—branches = left anterior descending (LAD); left circumflex; Ramos intermedius
22
Q
What is right coronary dominance?
A
In 85% of individuals, the RCA supplies the posterior descending artery
23
Q
Branch of LAD
A
Diagonal
24
Q
Branch of left circumflex
A
Obtuse marginal
25
What is Ramus intermedius?
A tri-furcation of the left coronary artery; found in 37% of people
26
What is the normal resting membrane potential?
-90 mV
27
Which electrolyte is high INSIDE a cardiac cell?
K+
28
Which electrolyte is high OUTSIDE a cardiac cell?
Na+
29
What is the chemical driving force?
K+ moving down it’s concentration gradient (from inside of the cell to outside of the cell)
30
What is the electrical driving force?
As K+ leaves the cell, negativity increases on the inside of the cell membrane and electrostatically attracts K+; this electrostatic force prevents K+ from leaving cell
31
What is the major determinant of the resting membrane potential?
Potassium
32
What is the Nernst equation? Balance of ___ + ___ = ___
Balance of chemical driving force + electrical driving force = no further net movement of K+
33
Na+, K+ - ATPase pump pumps Na+/K+ in what ratio?
3 Na+ out : 2 K+ in
34
The Na+, K+ - ATPase pump is partially inhibited by ___
Digitalis (digoxin)
35
What 3 things result in the resting membrane potential?
- Potassium diffusion
- Sodium diffusion
- Na+, K+ - ATPase
36
What type of cells (3) have the FAST RESPONSE action potential?
Myocardial muscle cells—atrial, ventricular, and purkinje myocardial fibers
37
What are the (5) phases of the fast response action potential?
- Phase 0
- Phase 1
- Phase 2
- Phase 3
- Phase 4
38
Phase 0 fast response action potential
Depolarization—Na+ into cell
39
Phase 1 fast response action potential
Partial repolarization—small amount of K+ out
40
Phase 2 fast response action potential
Plateau—slow influx of Ca+ through L-type calcium channels; stimulates the C-ICR (explained on separate flash card); some K+ moves out of the cell to counterbalance the large influx of calcium into the cell
41
Phase 3 fast response action potential
Repolarization—K+ moves out of the cell
42
Phase 4 fast response action potential
Resting membrane potential—ionic concentrations restored
43
What does C-ICR stand for/what does it involve/what phase does it occur during?
Calcium-induced calcium release
The slow influx of Ca++ into the cell (during phase 2 of the fast response action potential) stimulates a large amount of calcium to be released from the sarcoplasmic reticulum
44
ERP =
Effective refractory period—cannot regenerate another action potential
45
RRP =
Relative refractory period—can begin to generate another action potential
46
During what phases does ERP occur in the fast response action potential?
Between phases 1-2
47
During what phase(s) does RRP occur in the fast response action potential?
Phase 3
48
The characteristics of the upstroke of the action potential (depolarization, phase 0) depend almost entirely on inward movement of ___
Na+
49
There is a small inward ___ current during phase 0 depolarization (important for contraction)
Ca++
50
What produces the plateau phase (phase 2)?
Slow inward movement of Ca++ through L-type calcium channels; counterbalanced by outward K+ currents
51
Ventricular contraction persists throughout the action potential, so the ___ produces a long action potential to ensure forceful contraction of substantial duration
Long plateau = long action potential
52
___ is mainly responsible for repolarization (phase 3)
Outward K+ current
53
What 3 pumps are involved in the restoration of ionic concentrations (resting membrane potential, phase 4)?
- Na+,K+-ATPase
- Na+-Ca++ exchanger—driven by gradients, not electrical
- ATP-driven Ca++ pump
54
What type of cells have SLOW response action potentials?
Pacemaker cells—SA node, AV node
55
What are the 4 phases of the SLOW response action potential?
- Phase 0
- Phase 2
- Phase 3
- Phase 4
56
What phase is absent in the SLOW response action potential?
Phase 1
57
Phase 0–slow response action potential
Depolarization—caused by Ca++ influx
58
Phase 2–slow response action potential
Very brief
59
Phase 3–slow response action potential
- Not separated clearly from phase 2
| - K+ efflux causes repolarization
60
Phase 4–slow response action potential
Resting membrane potential
61
What does diastolic depolarization involve? — Inward ___ and ___; outward ___
Inward Na+ (not via typical Na+ channels) / Ca++
Outward K+ (opposes effects of other ions)
62
What phase of the slow response action potential does diastolic depolarization occur?
Phase 4
63
Slow depolarization of cell in phase ___ until activated in phase 0
4
64
Shorter diastolic depolarization = ___ pacer
FASTER
65
Longer diastolic depolarization = ___ pacer
SLOWER
66
What is the heart’s dominant pacemaker?
SA node
67
The ability of a focal area of the heart to generate pacemaking stimuli is known as ___
Automaticity
68
What term best describes this?—the SA node rate of firing is faster than any other node, so it will suppress other nodes from firing.
Overdrive suppression
69
At higher heart rates, more Na+ is extruded than K+ enters the cell. This tends to ___ the cells.
Hyperpolarize
70
Slow diastolic depolarization requires more time to reach ___
Threshold
71
What is the process by which an electrical stimulus triggers the release of calcium by the SR, initiating the mechanism of muscle contraction by sarcomere shortening?
Excitation-contraction coupling
72
What structure within the L-type calcium channels allows for communication between extra/intracellular?
T-tubules
73
What structure is responsible for calcium storage in the cell?
Sarcoplasmic reticulum
74
Cardiac action potentials are transmitted rapidly from cell-to-cell via ___
Gap junctions
75
The influx of Ca++ from the interstitial fluid during the action potential triggers the release of ___ from the ___; the free cytosolic ___ level increases; this is known as ___
Ca++ from the sarcoplasmic reticulum; the free cytosolic Ca++ level increases; this is known as calcium-induced calcium release (C-ICR)
76
Because the T-tubules are continuous with the extracellular fluid, ___ concentration of calcium becomes important for adequate heart contraction
Extracellular concentration of calcium
77
During muscle contraction—calcium binds to ___, which causes a conformational change in the ___ system
Calcium binds to troponin; causes a conformational change in the troponin-tropomyosin system
78
After calcium binds to troponin, this releases inhibition on ___, and the muscle ___ by the ___ mechanism
Releases inhibition on the actin and myosin interaction; the muscle shortens by the sliding filament mechanism
79
Sliding filament mechanism = ___ bind to ___, leading to ___ movement and reduction in ___, which causes muscle contraction
Myosin heads bind to actin, leading to cross-bridge movement and reduction in sarcomere length, which causes muscle contraction
80
Muscle contraction requires ___
ATP
81
ATP is required for muscle contraction to ___
Unbind myosin from actin—this allows the sarcomere to return to its original, relaxed length so another muscle contraction can occur
82
Normal PR interval
0.12-0.20 sec
83
Normal QRS
0.06-0.10 sec
84
AV node is situated on the ___ side of the interatrial septum, near the ostium of the ___
Right side of the interatrial septum; near ostium of the coronary sinus
85
How many phases are in the cardiac cycle?
Phases 1-7
86
What phases are in ventricular systole?
Phase 2
Phase 3
Phase 4
87
What phases are in ventricular diastole?
Phase 5
Phase 6
Phase 7
Phase 1
88
Phase 1
Atrial systole
89
Phase 2
Isovolumic contraction (all valves closed)
90
Phase 3
Rapid ejection (70% of ventricular volume is ejected)
91
Phase 4
Reduced ejection
92
Phase 5
Isovolumic relaxation (all valves closed)
93
Phase 6
Rapid ventricular filling—most LV filling occurs here
94
Phase 7
Diastasis (reduced ventricular filling)
95
Closure of what 2 valves generates the first audible heart sounds (S1)? What phase is this sound heard?
Tricuspid and mitral valves, close during phase 2–isovolumic contraction
96
___% of blood volume is ejected during phase 3, rapid ejection
70%
97
Closure of what valve generates the second audible heart sound (S2)? What phase is this sound heard?
Closure of the aortic valve, phase 5–isovolumic relaxation
98
All valves are closed during what 2 phases of the cardiac cycle?
Phase 2: isovolumic contraction
| Phase 5: isovolumic relaxation
99
S1 =
Closure of tricuspid/mitral valves
100
S2 =
Closure of aortic valve
101
Normal healthy heart valves are only audible when ___
Closing
102
An S3 heart sound is ___ and is associated with ___
Abnormal, associated with heart failure
103
S4 may be heard during what phase? What does it sound like?
Phase 1–atrial systole, sounds like a gallop
104
Very common to hear all 4 heart sounds in a person with ___
Heart failure
105
Phase 1 (atrial systole) contributes to ___ filling but is not essential
Ventricular filling
Contributes more to ventricular filling in a stiff heart
106
Dicrotic notch = ___ closure, marks end of ___
Aortic valve closure, marks end of ventricular systole
107
Atrial kick—at normal HR, contributes to ___% of ventricular filling
10% — insignificant
108
Atrial kick—at higher heart rates (i.e.: during exercise), can contribute up to ___% of ventricular filling
40%
109
There can be a loss of atrial kick in patients with ___
Atrial fibrillation
110
What are the 5 CVP waves?
```
A wave
C wave
V wave
X descent
Y descent
```
111
A wave =
Right atrial contraction; right after P wave/atrial depolarization
112
C wave =
Right ventricular contraction; just after QRS complex/ventricular depolarization
113
V wave =
Passive filling of right atrium; just after T wave begins/ventricular repolarization
114
Normal CO = ___ L/min
6 L/min
115
Strenuous exercise can kick CO up to ___ x normal
4-7 x normal
116
Cardiac output is the ___
Quantity of blood pumped into the aorta each minute
117
How do you calculate cardiac output?
CO = HR x SV
118
How do you calculate SV?
SV = EDV - ESV
EDV = how much is in the ventricle when you start to squeeze
ESV = how much is left after the squeeze
119
Venous return is the quantity of blood flowing from ___ into the ___ each minute
Veins into the right atrium each minute
120
Cardiac output and venous return should match—T/F
True
121
What are the 4 major determinants of cardiac output?
- Preload
- Afterload
- Contractility
- Heart rate
122
What has more of an effect on cardiac output—change in heart rate or change in stroke volume?
Change in heart rate
123
If HR increases, you have (more/less) time to fill, so you will have (increased/decreased) SV/CO
If HR increases, you have less time to fill, so you will have decreased SV/CO
124
Bowditch (Treppe) Effect—an increase in heart rate will also cause ___ inotropy d/t an increase in intracellular ___ with a higher heart rate
Positive inotropy d/t an increase in intracellular calcium
125
The Bowditch (Treppe) Effect is also known as...
“Staircase” phenomenon
126
The increase in intracellular calcium causes more ___ per minute
Depolarizations
127
Why is there more calcium lingering in the cell—the ___ pump doesn’t function as well (Bowditch/Treppe Effect)?
The Na+/Ca++ exchange pump doesn’t function as well because the Na+/K+-ATPase pump can’t keep up with the influx of Na+
128
Increased stroke volume = ___ end diastolic volume, ___ end systolic volume
Increased end diastolic volume, decreased end systolic volume
129
___ preload = increased end diastolic volume (and vice versa)
Increased preload = increased end diastolic volume
130
___ contractility = decreased end systolic volume (and vice versa)
Increased contractility = decreased end systolic volume
131
___ afterload = decreased end systolic volume (and vice versa)
Decreased afterload = decreased end systolic volume
132
___ is the initial stretching of the cardiac myocytes prior to contraction
Preload
133
Preload is related to the ___ length at the end of diastole
Sarcomere
134
Can we measure sarcomere length (aka preload) directly?
No—so we must use indirect indices of preload
135
What are 4 indirect indices of preload?
- LVEDV
- LVEDP
- PCWP
- CVP
136
Determinants of preload—how do venous return/total blood volume affect preload?
Increase in venous return/total blood volume = increase in preload
137
Determinants of preload—how does respiration (i.e.: mechanical ventilation) affect preload?
Mechanical ventilation = positive pressure ventilation, which will decrease venous return d/t increased intrathoracic pressures, which in turn will decrease preload
138
Determinants of preload—how does filling time (heart rate) affect preload?
Higher heart rate = less time for ventricular filling, decreased preload
139
Determinants of preload—how does ventricular compliance affect preload?
Increased compliance = increased preload
140
Determinants of preload—how does inflow/outflow resistance affect preload?
Less resistance = increased preload
141
“The heart pumps the blood that is returned to it” refers to what?
Frank-Starling Mechanism
142
The Frank-Starling Mechanism plays an important role in balancing ___
The output of the 2 ventricles
143
Frank-Starling—increasing ___ and ___ leads to an increase in stroke volume
Increasing venous return and ventricular preload
144
What is afterload?
The “load” that the heart must eject blood against
145
Afterload is closely related to the ___ pressure
Aortic
146
LaPlace’s Law refers to ___
Wall stress
147
Increased ventricular pressure = ___ wall stress
Increased wall stress
148
Increased ventricular radius = ___ wall stress
Increased wall stress
149
Increased wall thickness = ___ wall stress
DECREASED wall stress
Thick, hypertrophied ventricle = less wall stress
Thinner wall = increased wall stress
150
Frank-Starling looks at changes in ___
Volume
151
___ (increased/decreased) aortic pressure increases afterload
Increased
152
___ (increased/decreased) systemic vascular resistance increases afterload
Increased
153
Aortic valve ___ increases afterload
Stenosis—can’t get blood out of stenotic or stiff aorticle valve
154
Ventricular dilation ___ afterload
Increases—ventricle itself increases in size, but the surrounding wall is thin
155
What is the inherent capacity of the myocardium to contract independently of changes in afterload or preload?
Contractility
156
What is an alternate name for contractility?
Inotropy
157
Increased inotropy = ___ stroke volume, ___ end-diastolic volume
Increased stroke volume, decreased end-diastolic volume
158
Decreased inotropy = ___ stroke volume, ___ end-diastolic volume
Decreased stroke volume, increased end-diastolic volume
159
Sympathetic activation/catecholamines ___ inotropy
Increase
160
Heart rate ___ inotropy
Increases
161
Afterload ___ inotropy
Increases
162
Systolic failure and parasympathetic activation ___ inotropy
DECREASE
163
Venous pooling may significantly ___ cardiac output
Reduce
164
Spontaneous respiration—___ (increased/decreased) intrathoracic pressure results in a ___ (increased/decreased) right atrial pressure, which ___ venous return
Decreased intrathoracic pressure results in a decreased right atrial pressure, which enhances venous return
165
Mechanical ventilation— ___ (increased/decreased) intrathoracic pressure during positive-pressure lung inflation causes ___ (increased/decreased) right atrial pressure, which ___ (increases/decreases) venous return
Increased intrathoracic pressure during positive-pressure lung inflation causes increased right atrial pressure, which decreases venous return
166
Valsalva maneuver causes a large ___ (increase/decrease) in intrathoracic pressure, which ___ venous return to the right atrium (to the point of passing out)
Large increase; impedes venous return
167
Heart rate has a ___ (positive/negative) effect on end-diastolic volume—the faster the heart is going, the ___ (more/less) filling time you have, so the ___ (more/less) volume you have
Heart rate has a negative effect; the less filling time; less volume
168
Increased afterload = ___ end-systolic volume
Increased (less is squeezed out)
169
Cardiac function curve = ____ curve
Frank-Starling curve
170
Increase in right atrial pressure = ___ in cardiac output
Increase
171
___ afterload = increased cardiac output
Decreased
172
___ inotropy = increased cardiac output
Increased
173
Mean circulatory filling pressure = pressure at ___
Zero flow (~ 7 mm Hg)
174
Changes in ___ and ___ change the hinge point (mean circulatory filling pressure)—shift it left or right
Blood volume and venous compliance
175
Changes in ___ = same mean circulatory filling pressure, but will shift curve up or down
Systemic vascular resistance
176
X-axis of venous return curve =
Right atrial pressure
177
Y-axis of venous return curve =
Cardiac output
178
Why is there a plateau in the venous return curve?
As the right atrial pressure starts to fall below 0, CO begins to level off because the vena cava collapses, thus limiting venous return to the heart
179
Increase in blood volume shifts venous return curve/mean circulatory filling pressure ___
Up and to the right
180
Increase in venous compliance shifts venous return curve/mean circulatory filling pressure ___
Down and to the left
181
Decrease in blood volume shifts venous return curve/mean circulatory filling pressure ___
Down and to the left
182
Decrease in venous compliance shifts venous return curve/mean circulatory filling pressure ___
Up and to the right
183
Increased systemic vascular resistance shifts the venous return curve ___; how does it affect mean circulatory filling pressure?
Down and to the left; same mean circulatory filling pressure
184
Decreased systemic vascular resistance shifts the venous return curve ___; how does it affect mean circulatory filling pressure?
Up and to the right; same mean circulatory filling pressure
185
Mean circulatory pressure is the pressure in the circulatory system when there is ___ flow, CO = ___
NO flow; CO = 0
186
Mean circulatory pressure reflects ___ and ___
- Total blood volume
| - Compliance of the entire system
187
Cardiac output must equal venous return—T/F?
True!
188
The width of the pressure-volume loop represents ___
Stroke volume—the difference between EDV and ESV
189
How does afterload affect the pressure-volume loop? A change in afterload = a change in ___
Change in position on line of same slope
Increased afterload = lower point on line of same slope
Decreased afterload = higher point on line of same slope
190
How does contractility/inotropic state affect the pressure-volume loop? A change in contractility = a change in ___
Change in the slope of the line
Increased contractility = line with steeper slope
Decreased contractility = line with less slope
191
Change in slope of the ESPVR (end-systolic pressure volume relationship) = ___ issue
Contractility issue
192
Change in slope of the EDPVR (end-diastolic pressure volume relationship) = ___ issue
Compliance issue
193
X-axis of pressure volume loop =
LV volume (ml)
194
Y-axis of pressure volume loop =
LV pressure (mm Hg)
195
What is not a factor in pressure-volume loops?
Time
196
A pressure volume loop represents one ___
Cardiac cycle
197
Pressure volume loop moves in what direction?
Counterclockwise
198
If pressure volume loop gets wider, that means there is an increase in ___
Stroke volume/preload
199
Velocity is ___ related to cross-sectional area
INVERSELY
I.e.: capillaries
200
What is flow?
Volume per unit time
201
What is velocity?
Distance per unit time
202
What is the force exerted by the blood against any unit area of the vessel wall?
Blood pressure
203
One mm Hg of pressure = ___ cm of H2O pressure
1.36
204
Blood flow is driven by a ___ pressure
Perfusion pressure aka pressure gradient—normally represented by the difference between the arterial and venous pressures across the organ
205
Cerebral perfusion pressure (formula) =
CPP = MAP - CVP or ICP (whichever is higher)
206
Coronary perfusion pressure (formula) =
Coronary perfusion pressure = diastolic pressure - LVEDP
207
Poiseuille’s Law—flow is directly proportional to the ___
Pressure gradient
208
Poiseuille’s Law—flow varies directly as the ___ power of the radius
Fourth power
209
What is the most important factor for flow, according to Poiseuille’s Law?
RADIUS!
210
Poiseuille’s Law—doubling the radius of a tube causes a ___ increase in flow
16-fold (2^4)
211
Flow is inversely proportional to the ___ of the fluid
Viscosity
I.e.: polycythemia—blood is more viscous, results in less flow
212
Flow is inversely proportional to the ___ of the tube
Length
Longer tube = less flow
213
What is the impediment to blood flow in a vessel that cannot be measured by any direct means?
Resistance
214
What are the greatest resistance vessels in the circulation?
Arterioles
215
SVR formula
SVR = ( (MAP-CVP) / CO ) x 80
Because CVP is normally near 0 mm Hg, the calculation is sometimes simplified to:
SVR = MAP / CO
216
Normal SVR = ___ - ___
700-1600
217
Resistance in series is ___
Additive
RT = R1+ R2 + R3
218
Resistance in parallel has a ___ (increased/decreased) resistance by ___ (increasing/decreasing) the overall radius
Decreased resistance by increasing the overall radius
219
What is the measure of the tendency for turbulence to occur?
Reynold’s number
220
If R > 2,000...
Turbulence is likely to occur, even in a straight, smooth vessel!
221
Reynold’s number is directly proportional to what 3 things?
- Velocity (how fast it’s flowing)
- Density
- Diameter
222
Reynold’s number is INVERSELY proportional to ___
Viscosity
223
Viscosity is related to ___ flow
Laminar
224
Density is related to ___ flow
Turbulent
225
Relationship of hematocrit to blood viscosity—increased hematocrit = ___ (increased/decreased) viscosity, so ___ (more/less) flow
Increased hematocrit = increased viscosity, so less flow
226
Dicrotic notch = closure of ___
Aortic valve
227
Normal RA pressure
2-3 mm Hg
228
Normal RV pressure
25 mm Hg
229
Normal PA pressure
20-30 [systolic] / 8-12 [diastolic] (mean 25 mm Hg)
230
Normal PCWP
4-12 mm Hg
231
The best transducer placement is at a vertical height approximately 5 cm BELOW the left sternal border at the fourth intercostal space—T/F
True
232
Normal SV =
70 ml/min
233
Normal EF =
> 55%
234
Calculating cardiac output with thermodilution technique—cardiac output is ___ proportional to the area under the curve (AUC)
INVERSELY proportional
235
CO thermodilution technique—greater area under the curve, ___ (higher/lower) cardiac output
LOWER
236
Function of the ___ system is to distribute blood to the capillary systems in the body
Arterial system
237
The ___ regulate the distribution of flow of blood to the various capillary beds
Arterioles
238
Arterioles are AKA the “___” of the vascular system
Stopcocks
239
The ___ are the greatest resistance vessels
Arterioles
240
Pulse pressure =
Systolic BP - diastolic BP
241
How do you calculate MAP?
([2 * diastolic] + systolic ) / 3
242
Does MAP increase or decrease as blood is pumped out of LV and goes through the arteries >> arterioles >> capillaries >> venules?
MAP decreases
243
Where does pulse pressure disappear?
In the capillaries
244
Does the venous system contain a pulse pressure?
No
245
Pressures are very ___ (high/low) in the veins just before reentry into the heart
Low
246
The arterial system converts pulsatile blood flow to ___ blood flow
Continuous
247
Arterioles are the “___” of the circulation
“Stopcocks”
248
Veins are the ___ for the CV system
Reservoir
249
___% of blood volume may be stored in the veins
70%
250
Venous pump helps propel blood ___
Forward—enhances venous return
251
___ (increased/decreased) cardiac output increases CVP
Decreased CO (less blood leaving the heart)
252
___ (increase/decrease) in total blood volume increases CVP
Increase in total blood volume (increases preload)
253
Venous ___ (dilation/constriction) increases CVP
Venous constriction (more blood returns to the heart)
254
If you go from standing to supine position, does CVP increase or decrease?
CVP increases—blood pooled in legs returns to the heart
255
Arterial ___ (dilation/constriction) increases CVP
Dilation
256
How does respiratory activity increase CVP?
Increased respiratory rate promotes venous return (normal breathing is negative-pressure respiration...decreased intrathoracic pressure = more venous return)
257
Does exercise increase or decrease CVP?
Increases—promotes venous return to the heart
258
Arterioles contain ___ (thick/thin) smooth muscle
Thick smooth muscle
259
Arterioles give rise to ___, then to capillaries
Metarterioles
260
Metarterioles contain ___, which regulate flow into the capillaries
Precapillary sphincters
261
What regulates the opening/closing of the precapillary sphincters?
Local conditions in the tissues
262
Capillaries are ___-walled (thick/thin)
Thin-walled
263
Capillaries are the ___ vessels in the circulation
Smallest
264
Capillaries have the greatest ___ because they are so numerous
Cross-sectional area
265
Capillaries have the greatest ___ for exchange
Surface area
266
True capillaries are devoid of ___ and are incapable of ___
Devoid of smooth muscle and are incapable of active constriction
267
Capillary distribution varies from tissue to tissue—T/F
True
268
Why can capillaries withstand high intravascular pressures?
Because small capillaries have less wall stress—LaPlace’s law
269
What is the difference in pressure in cylindrical vessels vs. spherical vessels?
Cylindrical vessels have > pressure than spherical vessels—spherical vessel you divide by 2
270
How do O2, CO2, and lipid-soluble substances move through the capillary membrane?
Diffusion
271
How do H2O, electrolytes, and small molecules move through the capillary membrane?
Bulk flow
272
How do macromolecules move through the capillary membrane?
Via vesicles
273
How do ions and small molecules move through the capillary membrane?
Active transport
274
The permeability of the capillary endothelial membrane is the same in all body tissues—T/F
FALSE—permeability of the capillary endothelial membrane is NOT the same in all body tissues!!!
275
Body fluid compartments—ICF = ___%
40%
276
ECF = ___%
20%
277
ICF = ___ L
28 L
278
ECF = ___ L
14 L
279
ECF—interstitial fluid = ___ L
11 L
280
ECF—plasma = ___ L
3 L
281
Colloid goes into what body fluid compartment(s)?
Intravascular space (plasma)
282
0.9% NS/LR go into what body fluid compartment(s)?
ECF—both plasma and interstitial fluid compartments
283
0.9% NS and LR are ___ fluids
Isotonic
284
5% dextrose goes into what body fluid compartment(s)?
ICF and ECF—goes into ALL compartments
285
5% dextrose is what kind of fluid?
Isotonic until entering body; once it enters the body, the glucose gets metabolized and it becomes hypotonic
286
Capillary hydrostatic pressure, interstitial fluid hydrostatic pressure, and interstitial fluid osmotic pressure all move fluids ___
OUTWARD from the capillary
287
Plasma colloid osmotic pressure moves fluid ___
INTO the capillary
288
Lymphatics are lacking in ___ junctions
Tight junctions
289
Pumping by the lymphatic system is the basic cause of ___ pressure in the interstitial fluid space
Negative pressure
290
Plasma filtrate from the lymphatics is returned to the circulation by what 4 things?
- Tissue pressure
- Intermittent skeletal muscle activity
- Lymphatic vessel contraction
- System of one-way valves
291
Lymphatics return what 4 things to the circulation?
- Protein (albumin)
- Bacteria
- Fat
- Excess fluid
292
What are 4 things that cause edema?
- Lymphatic obstruction (can’t filter excess fluid out)
- Change in capillary permeability
- Reduction in plasma protein (reduced albumin)
- Increased capillary hydrostatic pressure (increased outflow on arterial end)
293
What are two ways peripheral blood flow is regulated?
- Extrinsic control
| - Intrinsic control
294
Extrinsic control =
- Nervous system
| - Humoral control
295
Intrinsic control =
Locally in the tissues
296
What is the main factor in acute control of local blood flow?
Tissue metabolic activity
297
Each tissue in the body is able to control its own local blood flow in proportion to ___
Its metabolic needs
298
What is this describing?—any intervention that results in an inadequate oxygen (nutrient) supply for the metabolic requirements of the tissues results in the formation of vasodilator substances which increase blood flow to the tissues
Metabolic mechanism
299
What specific condition contributes to metabolic mechanisms?
Hypoxia
300
What are 4 tissue metabolites/ions that contribute to metabolic mechanisms?
- K+
- CO2
- H+
- Lactic acid
301
Two types of hyperemia:
- Active hyperemia
| - Reactive hyperemia
302
Which type of hyperemia is this?—when any tissue becomes highly active, the rate of blood flow through the tissue increases. The increase in local metabolism causes the cells to devour tissue fluid and nutrients extremely rapidly and also increases large amounts of vasodilator substances (i.e.: exercise).
Active hyperemia
303
Which type of hyperemia is this?—when blood supply is blocked to a tissue for a few seconds to as long as an hour or more and then is unblocked, blood flow through the tissue usually increases immediately 4-7 times normal for a few seconds to many hours (i.e.: tourniquet).
Reactive hyperemia
304
Within limits, the peak blood flow and the duration of the reactive hyperemia are proportional to the duration of the ___
Duration of the occlusion
305
Autoregulation is the intrinsic ability of an organ to maintain a constant ___ despite changes in ___
Constant blood flow despite changes in perfusion pressure
306
The myogenic mechanism proposes that the stretch of vascular smooth muscle causes activation of ___ channels
Calcium channels
307
Myogenic mechanism—higher pressure ___ (increases/decreases) flow but also increases ___; vessel contracts back down to maintain increased pressure and returns to original flow
Higher pressure increases flow but also increases vessel diameter
308
Myogenic mechanism—when the lumen of a blood vessel is suddenly expanded, the smooth muscles respond by ___ in order to restore the vessel diameter and resistance; the converse is also true
Contracting
309
What are 4 vasoactive substances released from the endothelium?
- Nitric oxide (NO)
- Prostacyclin
- Endothelin
- Endothelial-derived hyperpolarizing factor (EDHF)
310
Nitric oxide =
Vasodilator; endothelium-derived relaxing factor
311
Prostacyclin =
Vasodilator
312
Endothelin =
Vasoconstrictor
313
What is the primary site in the brain for regulating sympathetic and parasympathetic (vagal) outflow to the heart and blood vessels?
The medulla
314
Chronotropy =
Heart rate
315
Inotropy =
Contractility
316
Dromotropy =
Conduction velocity
317
Lusitropy =
Relaxation
318
Sympathetic stimulation comes from ___ nerves and ___ gland
Sympathetic nerves and adrenal gland
319
Sympathetic nerves release ___
Norepinephrine
320
Adrenal gland releases mostly ___ and lesser amount of ___
Mostly epinephrine (80%); lesser amount of norepinephrine (20%)
321
Which has a longer lasting sympathetic effect, sympathetic nerves or the adrenal gland?
Adrenal gland
322
Adrenergic receptors (3)
- Alpha
- Beta 1
- Beta 2
323
Alpha receptor =
Vasoconstriction
324
Beta 1 =
Increased heart rate and contractility
325
Beta 2 =
Vasodilation
| Bronchodilation
326
What reflex is this?—increased arterial pressure causes parasympathetic response
Baroreceptor reflex
327
What reflex is this?—increase in volume causes sympathetic response; AKA atrial stretch receptor reflex
Bainbridge reflex
328
What reflex is this?—hypotension with bradycardia/parasympathetic response; also known as ventricular receptor reflex
Bezold-Jarisch reflex
329
What reflex is this?—high PCO2, low PO2, and high H+ can cause sympathetic response
Chemoreceptor reflex
330
What reflex is this?—hypertension with bradycardia
CNS ischemic response/Cushing response
331
What reflex is this?—water on the face causes vasoconstriction and slowing of HR
Diving reflex
332
Baroreceptor reflex is responsible for rapid adjustments of ___
Blood pressure—helps with postural changes in BP
333
Where are the baroreceptors located?
Carotid sinus and aortic arch
334
Bainbridge reflex—the atrial stretch receptors are ___ pressure receptors that respond to stretch; sense CV system ___
Low pressure; sense CV system volume
335
Where are the atrial stretch receptors located?
Vena cava—right atrial junction
| Pulmonary vein—left atrial junction
336
Bainbridge reflex—infusion of volume causes an ___ in heart rate d/t activation of atrial stretch receptors, which causes medullary center activation of sympathetic output to the SA node
Increase in HR—a small portion of HR increase is d/t stretch of the SA node (not mediated by atrial stretch receptors)
337
Bainbridge reflex—degree and direction of heart rate change depends on the prevailing heart rate; slow baseline heart rate = ___ HR with infusion; high baseline heart rate = ___ HR with infusion
Slow baseline = increased HR with infusion
High baseline = decreased HR with infusion
D/t baroreceptor reflex
338
How does the Bainbridge reflex affect urine output and BP? (remember, these are not technically part of the Bainbridge reflex...these are just additional effects)
- Increased urine output
| - Decreased BP
339
What elicits the Bezold-Jarisch reflex?
Strong contraction of an under filled ventricle
340
Bezold-Jarisch reflex plays a role in ___ regulation
Blood pressure regulation
341
Bezold-Jarisch reflex is possibly involved in what 2 things?
- Cardiac arrest during spinal anesthesia
| - Vasovagal syncope
342
Where are the peripheral chemoreceptors located?
Aortic and carotid bodies
Remember—the baroreceptors are located in the carotid sinus and aortic arch (NOT the same thing)
343
The peripheral chemoreceptors in the aortic and carotid bodies are primarily concerned with regulation of ___
Respiration
344
___ (increased/decreased) arterial blood oxygen tension, ___ (increased/decreased) CO2, and/or ___ (increased/decreased) hydrogen ion concentration results in excitation of the vasomotor center
Decreased arterial blood oxygen tension, increased CO2, and increased H+ concentration results in excitation of the vasomotor center
345
The peripheral chemoreceptor reflex, aside from its role in the regulation of respiration, helps to return the blood pressure back to a normal level; it is usually not stimulated strongly until the arterial pressure falls below ___ mm Hg
Below 80 mm Hg
346
CNS ischemic response is the result of decreased blood flow to the vasomotor center in the ___
Medulla
347
CNS ischemic response—increased local concentration of ___ results in sympathetic stimulation in the medulla; results in ___ (increased/decreased) BP; very powerful activator of the sympathetic nervous system
Increased local concentration of CO2; results in increased BP
348
Cushing response is a special type of ___
CNS ischemic response
349
Cushing response is the result of increased ___
Intracranial pressure
350
Cushing response—increased ___ results in increased ___, until blood flows once again in the vessels of the brain
Increased ICP results in increased BP
351
What is Cushing’s triad?
- Increased ICP
- Increased BP (hypertension)
- Bradycardia
352
Diving reflex—cold water to face = ___
Reduced heart rate (which results in reduced O2 consumption)
353
Sinus arrhythmia—heart rate ___ with inspiration, ___ with expiration
Increases with inspiration (increased sympathetic activity with inspiration), slows with expiration (increased parasympathetic activity with expiration)
354
Renin-angiotensin-aldosterone system—renin is released from the ___
Kidney
355
Renin converts ___ to ___
Angiotensinogen to angiotensin I
356
Angiotensin converting enzyme (ACE) converts ___ to ___
Angiotensin I to angiotensin II
357
Angiotensin II causes release of aldosterone from the ___
Adrenal cortex
358
Aldosterone results in ___ and ___ retention; systemic ___ = ___ BP
Sodium and water retention; systemic vasoconstriction = increased BP
359
Vasopressin is AKA ___
Antidiuretic hormone
360
Vasopressin is released from the ___
Posterior pituitary
361
Vasopressin causes ___ and ___ BP
Vasoconstriction and increases BP
362
Vasopressin causes ___ of fluid at the kidney level and ___ blood volume
Reabsorption of fluid at the kidney level and increases blood volume
363
Atrial Natriuretic Peptide is released as a result of ___ distention; ___ stimulation; angiotensin ___; and ___
Atrial distention; sympathetic stimulation; angiotensin II; and endothelin
364
ANP ___ SVR; ___ BP; causes an ___ in urine output and sodium loss, leading to a ___ in blood volume
Decreases SVR; decreases BP; causes an increase in urine output and sodium loss, leading to a decrease in blood volume
365
What are the indirect effects of hypoxia (lesser degree)?
Sympathetic nervous system stimulation—increase HR, contractility, SVR
366
What are the direct effects of hypoxia? (if hypoxemia is very profound)
Decreased contractility, HR
367
What are indirect effects of hypercarbia?
SNS activation—increase HR, contractility, SVR
368
What are direct effects of hypercarbia?
Decreased contractility
369
Do the major epicardial arteries contribute to coronary vascular resistance?
NO—epicardial conductance vessels do NOT contribute significantly to coronary vascular resistance—only a small % of a resistance normally
370
What vessels contribute most to total coronary vascular resistance?
Intramyocardial vessels (Arterioles)
371
Is capillary density increased or decreased in the myocardium?
Increased!
372
What are the 3 major determinants of myocardial oxygen demand?
Heart rate
Contractility
Systolic wall tension
373
What are the 3 major determinants of myocardial oxygen supply?
Vascular resistance
Coronary blood flow
Oxygen-carrying capacity
374
Resting oxygen consumption of the heart is higher or lower relative to other organs in the body?
Higher
375
What is the pressure gradient that drives blood through the coronary circulation?
Coronary perfusion pressure
376
Formula for coronary perfusion pressure =
Diastolic BP - LVEDP (or PCWP)
377
What organ extracts oxygen to the greatest extent?
The heart
378
Why is the coronary sinus PO2 value so low (normally in range of 20-22 mm Hg; % sat = 32-38%)?
It is low because the heart extracts so much oxygen
379
Can the heart increase O2 extraction significantly?
No—can only minimally increase O2 extraction
380
Increases in O2 demand must be met by ___
Increased coronary blood flow
381
When does the majority of coronary blood flow occur? During systole or diastole?
During diastole in the left ventricle because ventricular myocytes collapse the coronary arterial supply vessels as they contract (extravascular compression); during diastole, the compressive forces are removed, and blood surges through the coronary musculature at peak rates
382
The idea that ventricular myocytes collapse the coronary arterial supply vessels as they contract is known as ___
Extravascular compression
383
Extravascular compressive forces are greater in the ___ layer and least near the ___ layer
Greater in the subendocardium (inner) layer; least near the subepicardial (outer) layer
384
Which layer of the heart is most susceptible to ischemia?
Subendocardium > midmyocardium > subepicardium
385
Changes in ___ affect myocardial oxygen consumption LESS than do changes in other factors
Preload (less effect than increased heart rate, inotropy, or afterload)
386
Coronary vessels have to be at least ___% occluded before interventional measures are taken (i.e.: balloon angioplasty, stent placement, arterial bypass surgery)
75%
387
What is the final intracellular ion disturbance that leads to impaired myocardial contraction and cell death?
Increased intracellular calcium
388
What best describes the following?—single or multiple brief periods of ischemia can be protective against a subsequent prolonged ischemic insult. The brief periods of ischemia appear to “precondition” myocardium against reversible or irreversible tissue injury, including stunning, infarction, and the development of malignant ventricular arrhythmias.
Ischemic preconditioning (IPC)
389
What agents have effects that mimic IPC?
Inhaled anesthetic agents—SEVO!
390
What channels play an important role in IPC?
K+ ATP channels
391
What are 3 major factors that affect flow across any valvular lesion?
- Valve area (more area = better flow; less area = less flow)
- Square root of the hydrostatic pressure gradient across the valve (higher pressure gradient = more flow and vice versa)
- The time duration of transvalvular flow (less time = less flow and vice versa)
**Increasing any of these major factors increases transvalvular flow; conversely, decreasing any of these major factors decreases transvalvular flow**
392
It is desirable to INCREASE transvalvular flow with ___ lesions
Stenotic lesions
393
It is undesirable to increase flow with ___ lesions
Regurgitant
394
Goal for regurgitant lesions is to ___ flow
Reduce flow
395
How can you reduce flow in regurgitant lesions?
Increase HR—there will be less time for regurgitant flow to occur across a valve
396
Goal for stenotic lesions is to ___ flow
Maximize flow
397
How can you maximize flow for stenotic lesions?
Slow HR down—you will have a longer period of time for flow to occur across that stenotic valve
398
The valve area in regurgitant or stenotic lesions can respond to changes in loading conditions (preload, afterload)?
Regurgitant lesions—the valve area will respond to changes in preload, afterload
399
The valve area in stenotic lesions is generally ___
Fixed—so they are NOT affected by changes in preload or afterload
400
What kind of murmur (systolic/diastolic) is heard with aortic stenosis?
Systolic murmur
401
What kind of murmur (systolic/diastolic) is heard with aortic regurgitation?
Diastolic murmur
402
What kind of murmur (systolic/diastolic) is heard with mitral stenosis?
Diastolic murmur
403
What kind of murmur (systolic/diastolic) is heard with mitral regurgitation?
Systolic murmur
404
Aortic stenosis usually has a long ___ period
Asymptomatic
405
Aortic stenosis presenting with angina (with no planned surgical intervention) typically has life span of ___
5 years
406
Aortic stenosis presenting with syncope (with no planned surgical intervention) typically has life span of ___
3 years
407
Aortic stenosis presenting with CHF (with no planned surgical intervention) typically has life span of ___
2 years
408
Aortic stenosis is considered an independent risk factor for perioperative ___
Perioperative morbidity
409
Aortic stenosis—want ___ preload
Increased preload—to fill non compliant LV
410
Aortic stenosis—HR goals
Want to avoid extremes of HR, maintain sinus rhythm
411
Aortic stenosis—SVR goals
Increased; AVOID hypotension
412
Aortic regurgitation is AKA ___
Aortic insufficiency
413
Aortic regurgitation has a long ___ period, during which the LV undergoes progressive ___ hypertrophy
Asymptomatic period; eccentric hypertrophy
414
What is eccentric hypertrophy?
LV chamber size is normal, but the LV wall is very thick—occurs with pressure overloading
415
Two main symptoms of aortic regurgitation:
- CHF (fatigue, exercise intolerance, ankle swelling)
| - Angina
416
Patients with aortic regurgitation develop pressure or volume overloading?
VOLUME overloading
417
___ (increased/decreased) coronary perfusion pressure with aortic regurgitation because you have ___ (increased/decreased) diastolic pressure in the LV, ___ (increased/decreased) diastolic pressure in the aorta
Decreased coronary perfusion pressure
Increased diastolic pressure in the LV
Decreased diastolic pressure in the aorta
418
Aortic regurgitation—want ___ preload
Increased preload to maintain forward flow (avoid hypovolemia)
419
Aortic regurgitation—___ heart rate
Increased HR—reduces diastolic time and reduces regurgitant fraction
420
Aortic regurgitation—___ SVR
Decreased SVR—afterload reduction is helpful in improving forward flow
421
Mitral stenosis—maintain ___ heart rate
Decreased—slow to allow time for ventricular filling
422
Mitral stenosis—maintain ___ PVR because these patients have elevated ___ pressures
Decreased PVR d/t elevated PA pressures
423
Mitral stenosis—avoid what 3 things so we don’t further elevate PA pressures?
Avoid acidosis, hypercarbia, and hypoxemia
424
Mitral regurgitation—___ HR; leads to a ___ in LV volume, ___ forward flow, and ___ regurgitant fraction
Increased HR; leads to a decrease in LV volume, increased forward flow, and decreased regurgitant fraction
425
Mitral regurgitation—___ contractility tends to ___ forward flow and ___ regurgitant fraction by constricting mitral annulus
Increase contractility tends to increase forward flow and reduce regurgitant fraction
426
Mitral regurgitation—___ SVR
Decreased SVR—afterload reduction is helpful in improving forward flow
427
Hypertrophic cardiomyopathy goals—___ preload; ___ SVR; ___ HR; ___ inotropy
Increase preload (reduces gradient across LVOT); increase SVR (reduces gradient across LVOT); decrease HR (reduces oxygen demand of thickened myocardium); decrease inotropy (reduces gradient across LVOT)
