Cardiovascular Physiology Flashcards
1
Q
3 organs that receive the most percentage of cardiac output:
A
Renal (25%), Gastrointestinal (25%), Skeletal muscle (25%)
Others: Brain 15%, Coronary 5%, Skin 5%
2
Q
2 arteries that carry deoxygenated blood:
A
Pulmonary artery
Umbilical artery
3
Q
The veins are called the reservoir of blood. How much of systemic blood is found in veins?
A
64%
4
Q
What is the normal right atrial pressure?
A
0 - 4 mmHg
5
Q
What is the normal pressure in the systemic capillaries?
A
17 mmHg
6
Q
Blood flow velocity is fastest in the:
A
Aorta
7
Q
Control conduits for blood flow, mainly under sympathetic control:
A
Arterioles
8
Q
Blood flow velocity is slowest in the:
A
Capillaries
9
Q
The capillaries cannot constrict or dilate because they lack:
A
Tunica media (only composed of a single layer of endothelial cells)
10
Q
These structures allow capillary beds to be open or closed
A
Meta-arterioles and pre-capillary sphincter
11
Q
What happens when systemic arterioles vasoconstrict?
A
TPR/SVR: increases
Blood flow: decreases
12
Q
What happens when systemic arterioles vasodilate?
A
TPR/SVR: decreases
Blood flow: increases
13
Q
What happens to blood pressure when TPR increases?
A
BP increases
14
Q
What happens when veins vasoconstrict?
A
Venous return increases
15
Q
Flow that is streamlined, highest at the center and lowest at the walls
A
Laminar flow
16
Q
Flow that is disorderly, associated with high Reynold’s number; seen in anemia (dec blood viscosity) and vessel narrowing (inc blood velocity)
A
Turbulent flow
17
Q
Normal pressure in the pulmonary arteries:
A
25/8 mmHg
18
Q
Normal pressure in the pulmonary capillaries:
A
7 mmHg
19
Q
3 organs that receive the most percentage of cardiac output:
A
Renal (25%), Gastrointestinal (25%), Skeletal muscle (25%)
Others: Brain 15%, Coronary 5%, Skin 5%
20
Q
Reynold’s number for laminar flow
A
21
Q
Reynold’s number for turbulent flow
A
> 2000
22
Q
A strain in the structure of a substance produced by pressure, when its layers are laterally shifted in relation to each other
A
Shear
23
Q
Shear is highest in:
A
walls of the blood vessel
24
Q
Shear is lowest in:
A
center of the blood vessel
25
What is the consequence of shear?
Decreased blood viscosity
26
Compliance of veins vs arteries
24x higher compliance
27
Effects of aging on the compliance of arteries
Decreases compliance
28
Highest arterial blood pressure
Systolic pressure
29
Lowest arterial blood pressure
Diastolic pressure
30
____ = systolic pressure - diastolic pressure
Pulse pressure
31
____ = stroke volume/arterial compliance
Pulse pressure
32
____ = 2/3 (diastole) + 1/3 (systole)
Mean arterial pressure
33
Estimates left atrial pressure
Pulmonary capillary wedge pressure
34
Estimates left atrial pressure
Pulmonary capillary wedge pressure
35
2 arteries that carry deoxygenated blood:
Pulmonary artery
| Umbilical artery
36
The veins are called the reservoir of blood. How much of systemic blood is found in veins?
64%
37
What is the normal right atrial pressure?
0 - 4 mmHg
38
What is the normal pressure in the systemic capillaries?
17 mmHg
39
Blood flow velocity is fastest in the:
Aorta
40
Control conduits for blood flow, mainly under sympathetic control:
Arterioles
41
Blood flow velocity is slowest in the:
Capillaries
42
The capillaries cannot constrict or dilate because they lack:
Tunica media (only composed of a single layer of endothelial cells)
43
These structures allow capillary beds to be open or closed
Meta-arterioles and pre-capillary sphincter
44
What happens when systemic arterioles vasoconstrict?
TPR/SVR: increases
| Blood flow: decreases
45
What happens when systemic arterioles vasodilate?
TPR/SVR: decreases
| Blood flow: increases
46
What happens to blood pressure when TPR increases?
BP increases
47
What happens when veins vasoconstrict?
Venous return increases
48
Flow that is streamlined, highest at the center and lowest at the walls
Laminar flow
49
Flow that is disorderly, associated with high Reynold's number; seen in anemia (dec blood viscosity) and vessel narrowing (inc blood velocity)
Turbulent flow
50
Normal pressure in the pulmonary arteries:
25/8 mmHg
51
Normal pressure in the pulmonary capillaries:
7 mmHg
52
Reynold's number for laminar flow
53
Reynold's number for turbulent flow
> 2000
54
A strain in the structure of a substance produced by pressure, when its layers are laterally shifted in relation to each other
Shear
55
Shear is highest in:
walls of the blood vessel
56
Shear is lowest in:
center of the blood vessel
57
What is the consequence of shear?
Decreased blood viscosity
58
Compliance of veins vs arteries
24x higher compliance
59
Effects of aging on the compliance of arteries
Decreases compliance
60
Highest arterial blood pressure
Systolic pressure
61
Lowest arterial blood pressure
Diastolic pressure
62
____ = systolic pressure - diastolic pressure
Pulse pressure
63
____ = stroke volume/arterial compliance
Pulse pressure
64
____ = 2/3 (diastole) + 1/3 (systole)
Mean arterial pressure
65
Synonym of right atrial pressure
Central venous pressure
66
Estimates left atrial pressure
Pulmonary capillary wedge pressure
67
ECG: atrial depolarization
P wave
68
ECG: AV node conduction
PR segment
69
ECG: correlates with conduction time/velocity through the AV node
PR interval
70
ECG: ventricular depolarization
QRS complex
71
Causes of circus movements:
long conduction pathway, decreased conduction velocity, short refractory period
72
ECG: period of depolarization + repolarization of ventricles
QT interval
73
ECG: correlates with plateau of ventricular action potential
ST segment
74
What happens when sympathetic NS stimulates the AV node?
Increase in conduction velocity, decrease in PR interval
75
What happens when parasympathetic NS stimulates the AV node?
Decrease in conduction velocity, increase in PR interval
76
ECG: hypokalemia
flat/inverted T waves
77
ECG: hyperkalemia
low P waves, tall T waves
78
ECG: hypocalcemia
prolonged QT interval
79
ECG: hypercalcemia
shortened QT interval
80
ECG: STEMI
ST segment elevation
81
ECG: NSTEMI
ST segment depression
82
```
Ventricular action potential:
Na influx (depolarization)
```
Phase 0
83
```
Ventricular action potential:
K efflux (complete repolarization)
```
Phase 3
84
Ventricular action potential:
| RMP
Phase 4
85
Ventricular action potential:
| Ca++ influx (plateau)
Phase 2
86
```
Ventricular action potential:
K efflux (partial repolarization)
```
Phase 1
87
SA node action potential:
| Slow Na influx towards threshold
Phase 4
88
```
SA node action potential:
Ca influx (depolarization)
```
Phase 0
89
```
SA node action potential:
K efflux (repolarization)
```
Phase 3
90
Why is the SA node capable of authorhythmicity?
Opening of the K channels always triggers the opening of the Na channels (phase 3 is always followed by phase 4)
91
What happens to the slope of phase 4, action potential and heart rate when you stimulate the B1 receptors of the heart?
Slope: more steep
AP: shorter
HR: increase
92
What happens to the slope of phase 4, action potential and heart rate when you stimulate the M2 receptors of the heart?
Slope: more flat
AP: longer
HR: decrease
93
The SA node is called the master pacemaker. The AV node, bundle of His and Purkinje cells are called?
Latent pacemaker
94
Which node has the slowest conduction velocity?
AV node
95
Which node has the fastest conduction velocity?
Bundle of His, Purkinje fibers, ventricles
96
What is the basis for AV nodal delay (0.13secs)?
Decreased gap junctions in that area
97
Which Na channel accounts for SA node automaticity?
If channels (slow "funny" Na channels)
98
```
Isovolumic contraction:
Preceded by ______ in the ECG
______ of atrial pressure is seen
Semilunar valves are: _____
Ventricular pressure: ______
Ventricular volume: ______
```
```
QRS complex
c-wave
SL valves are closed
VP: increases
VV: remains the same
```
99
Inhibition of "pacemaking" of latent pacemakes by the SA node
Overdrive suppression
100
AV block that causes fainting in patients due to initially suppressed state of Purkinje fibers
Stokes-Adams syndrome
101
Condition when latent pacemaker assume pacemaking activity
Ectopic pacemaker
102
Reduced ventricular ejection:
_____ occurs in the ECG
Ventricular pressure: _____
Ventricular volume: _____
T wave
VP: decrease
VV: decrease
103
Occurs when, in the propagation of AP around the ventricles, the signal never reaches an area with absolute refractory period; basis for Vfib
Circus movements
104
Causes of circus movements:
long conduction pathway, decreased conduction velocity, short refractory period
105
All Na inactivation gates close, AP cannot be generated
Absolute refractory period
106
Some Na inactivation channels start to open, AP cannot be conducted
Effective refractory period
107
AP can be conducted and generated but higher than normal stimulus is required
Relative refractory period
108
All Na inactivation gates are open and membrane potential is higher than RMP; cell is more excitable than normal
Supranormal period
109
Produces changes in contractility
Inotropic effect
110
Produces changes in rate of relaxation
Lusitrophic effect
111
Produces changes in heart rate
Chronotrophic effect
112
Produces changes in conduction velocity
Dromotrophic effect
113
Inotropes affect the:
Stroke volume
114
Chronotropes affect the:
SA node
115
Dromotropes affect the:
AV node
116
Beta 1 stimulation of the heart would cause:
Stronger (positive inotrope), Briefer (positive lusitrope) and more frequent (positive chronotrope) contractions
117
An increase in preload will increase stroke volume within certain physiologic limits
Frank-Starling mechanism
118
Left ventricular end diastolic volume is directly proportional to what?
Venous return, right atrial pressure
119
What happens to SV and CO when preload increases?
Both increase
120
What happens to SV and CO, and velocity of sarcomere shortening when afterload increases?
All decrease
121
Blood ejected by the ventricle per heart beat; Equal to EDV-ESV
Stroke volume (Normal: 70mL)
122
Percentage of EDV that is actually ejected by the ventricle; Equal to SV/EDV
Ejection fraction (Normal: 55%)
123
Total blood volume ejected per unit of time; Equal to HR x SV
Cardiac output (Normal resting: 5L/min)
124
How long can the brain, heart and skeletal muscles last without O2?
Brain: 4 minutes
| Heart and skeletal muscles: 6 hours
125
Primary source of energy for stroke work:
Fatty acids
126
Work per unit of time; Equal to CO x Aortic pressure
Cardiac minute work
| 2 components: volume work (cardiac output) and pressure work (aortic pressure)
127
Ratio of work output to total chemical energy expenditure
Maximum efficiency of cardiac contraction
| Normal: 20 - 25%; most of energy is converted to heat
128
Cardiac events that occur in a single heartbeat
Cardiac cycle
129
Atrial contraction:
Occurs during the _______
Preceded by ______ in the ECG
______ of atrial pressure is seen
distal third of diastole
p wave
a-wave
130
What is the cause of the 4th heart sound?
Due to atria contracting against stiff ventricles, as seen in LV hypertrophy
131
```
Isovolumic contraction:
Preceded by ______ in the ECG
______ of atrial pressure is seen
Ventricular pressure: ______
Ventricular volume: ______
```
QRS complex
c-wave
VP: increases
VV: remains the same
132
The first heart sound is heard during:
Closure of AV valves during isovolumic contraction
133
Rapid ventricular ejection:
Ventricular pressure: _____
Ventricular volume: _____
VP: rapidly increase
VV: decrease
134
Phase of the cardiac cycle wherein semilunar valves open and blood flows from LV to aorta; atrial filling also begin
Rapid ventricular ejection
135
Reduced ventricular ejection:
_____ occurs in the ECG
Ventricular pressure: _____
Ventricular volume: _____
T wave
VP: decrease
VV: decrease
136
```
Isovolumic relaxation:
_____ of aortic pressure is seen
_____ of atrial pressure is seen
AV valves are: ______
Ventricular pressure: _____
Ventricular volume: _____
```
```
Incisura
v wave
AV valves are closed
VP: decreases
VV: remains the same
```
137
The second heart sound is heard during:
Closure of the semilunar valves during isovolumic relaxation
138
Rapid ventricular filling:
occurs during _________
_____ heart sound may be heard
first 1/3 of diastole
| 3rd heart sound
139
Reduced ventricular filling (diastasis)
| occurs during _________
middle 1/3 of diastole
140
What is the longest phase of the cardiac cycle?
Diastasis
141
Where are murmurs best heard?
Aortic: 2nd ICS RPSB
Pulmonic: 2nd ICS LPSB
Tricuspid: 4th ICS LPSB
Mitral: 5th ICS LMCL
142
Physiologic murmurs occur only during systole or diastole?
Systole
143
What is the murmur that is heard both on systole and diastole?
Continuous machinery murmur of PDA
144
Center responsbile for regulation of HR and BP
Vasomotor area of the medulla
Lateral: Excitatory
Medial: Inhibitory
145
What is the 1st line in maintaining blood pressure and buffers minute-to-minute changes in BP?
Baroreceptors (stretch receptors)
146
Where are the baroreceptors found?
```
Carotid sinus (respond to increase/decrease in pressure from 50-180 mmHg)
Aortic arch (respond to increase in pressure >80mmHg)
```
147
Responds to low O2 or high CO2 concentration whenever BP is
Chemoreceptors
148
Where are the chemoreceptors found?
Carotid and aortic bodies
149
Low pressure receptors (cardiopulmonary receptors) detect fullness of vascular system. In response to increased intravascular volume, these 4 mechanisms are activated:
1. Increase ANP (increase Na and H2O excretion)
2. Decrease ADH (increase UO)
3. Renal vasodilation (increase UO)
4. Increase HR (Bainbridge reflex)
150
Differentiate Frank-Starling mechanism from Bainbridge reflex
Frank Starling: Increased VR --> Increase SV --> Increase CO
| Bainbridge: Increased VR --> Increased HR --> Increase CO
151
The vasomotor center itself responds directly to ischemia during low BP; all systemic arterioles vasoconstrict severely except coronary and cerebral vessels
CNS ischemic response
152
Occurs in response to increased intracranial pressure
Cushing reaction or Cushing reflex
153
What is the triad of Cushing reflex?
Hypertension, Bradycardia, Irregular respirations
154
What is the mechanism of hypertension seen in Cushing reflex?
Activation of the CNS ischemic response causes massive vasoconstriction of all systemic arterioles
155
What is the mechanism of bradycardia seen in Cushing reflex?
Activation of the baroreceptor reflex due to the high BP activates the parasympathetic system to decrease HR
156
What is the mechanism of irregular respirations seen in Cushing reflex?
Compression of the brainstem where the respiratory centers are found
157
How long can the brain, heart and skeletal muscles last without O2?
Brain: 4 minutes
| Heart and skeletal muscles: 6 hours
158
What is the normal net filtration?
2mL/min
159
Lymphatic system produces how much lymph per day?
2-3 L
160
What is the function of the lymphatic system?
Reabsorbs proteins and excess fluid back to the circulatory system
161
Special lymphatics used to absorb fat
Lacteals
162
Why should there be local control of blood flow?
For the tissues to get their proper amounts of oxygen and nutrients
For thermoregulation
For homeostasis
163
Organ with the highest blood flow under basal conditions:
Liver
164
Theory which states that when vascular smooth muscle are stretched, there's a reflex contraction and vice versa
Myogenic theory
165
Theory which states that vasodilator metabolites are produced as a result of metabolic activity
Metabolic theory
166
Theory which states that certain substances increase blood flow during deoxygenation such as adenosine
Vasodilator theory
167
Theory which states O2 is needed during vascular muscle contraction, thus lack of O2 would lead to vasodilation
Oxygen lack theory
168
Theory which state that nutrients such as thiamine are needed for ATP formation thus vascular muscle contraction, thus lack of nutrients would lead to vasodilation
Nutrient lack theory
169
Increase in blood flow in response to brief period of decreased blood flow
Reactive hyperemia (blood flow increased 4-7x the normal)
170
Blood flow increases to meet increased metabolic demand
Active hyperemia
171
Most potent vasoconstrictor:
Vasopressin
172
Released as a result of blood vessel damage and causes arteriolar vasoconstriction; implicated in migraine
Serotonin
173
Released by damaged endothelium
Endothelin
174
Substance that causes platelet aggregation and vasoconstriction
Thromboxane A2
175
Counteracts the effects of TXA2
PGI2
176
Vasodilates upstream blood vessels
Nitric oxide (EDRF)
177
Causes arteriolar dilation and venous constriction leading to increased filtration (local edema)
Bradykinin and Histamine
