cardiac physiology Flashcards
1
Q
What is the number 1 cause of death?
A
cardiovascular disease
2
Q
What is the major underlying cause of cardiovascular disease?
A
ischemia due to atheroclerosis, thrombus, and/or artery spasm
3
Q
what cause has been linked to atherogenesis?
A
high blood cholesterol
4
Q
What kind of mechanisms link couple dyslipidemia to atheroma formation?
A
Inflammatory mechanisms
5
Q
What are the characteristics associated with early atherogeneis?
A
leukocyte recruitment and expression of pro-inflammatory cytokines
6
Q
What condition is promoted by inflammatory pathways and is responsible for MI and most strokes?
A
thrombosis
7
Q
T/F: the nervous system can modulate inflammation.
A
T; the nervous system can do pretty much anything.
8
Q
What is the term for prevention of blood loss?
A
hemostasis
9
Q
What are the mechanisms of blood loss prevention?
A
vascular spasm, formation of a platelet plug, blood coagulation, and fibrous tissue growth to seal
10
Q
What neural reflex is associated with vascular constriction?
A
SNS induces constriction from pain
11
Q
What is responsible for most of the constriction during hemostasis?
A
local myogenic spasm
12
Q
What local humoral factor is associated with hemostasis?
A
thromboxane A2 from platelets
13
Q
What makes platelets unlike whole cells?
A
they cannot divide
14
Q
What phospholipid contatins platelet factor 3 and initiates clotting?
A
thromboplastin
15
Q
Where are the glycoproteins located that avoid the normal endothelium but adhere to damaged area?
A
platelet cell membrane
16
Q
When platelets contact a damaged area, what 4 things do they do?
A
swell, take an irregular form with irradiating surfaces, contractile proteins contract causing granule release, and secrete things (ADP, Thromboxane A2, and serotonin)
17
Q
T/F: Thromboxane A2 is a vasodilator
A
False; it is a vasconstrictor
18
Q
What is the half-life of platelets?
A
8-12 days
19
Q
T/f: platelets are only important in severe ruptures
A
False; platelets are important in minute ruptures
20
Q
What is the role of endothelium with respect to platelets?
A
prevents platelet aggregation
21
Q
What is the name of the vasodilator that stimulates platelet adenyl cyclase which suppresses release of granules and limits platelet extension?
A
PGI2 (prostacyclin)
22
Q
Other than producing PGI2 and preventing platelet aggregationg, what is the other role of endothelium in CVP?
A
Producing factor VIII (clotting)
23
Q
What do Aspirin and Ibuprofen block production of by blocking fatty acid cyclooxygenase?
A
thromboxane A2
24
Q
What does cyclooxygenase convert arachidonic acid to?
A
PGG2 and PGH2 (intermediates)
25
What makes anticoagulants different from lysis of clots?
anticoagulants prevent clots from forming instead of dissolving clots that have already formed.
26
T/F: heparin dissolves clots.
false; heparin is an anticoagulant and prevents clots from forming
27
T/F: plasmin prevents clots from forming.
false; plasmin is associated with lysis of clots (dissolves clots that have already formed)
28
what is the inactive form of plasmin which circulates in the blood?
plasminogen
29
Where are a few endogenous activators of plasminogen found?
in tissues, plasma, and urine
30
What are a couple of exogenous activators of plasminogen?
streptokinase and tPA (tissue plasminogen activator)
31
What process that involves the proteolytic enzyme plasmin may liquefy clots?
fibrinolysis
32
How soon are exogenous activators such as tPA administered after acute blockage for therapeutic effects?
within 3 hours
33
Most of the tissue damage associated with infarction occurs upon what action?
reperfusion
34
What type of injury is associated with the formation of highly reactive oxygen species with unpaired electrons (free radicals)?
reperfusion injury (I'm sure there are other injuries involved with this formation too.
35
When pressure on tissues is relieved and again perfused with blood, free radicals are generated. This injury is known as what?
reperfusion injury
36
The ability to open up alternate routes of blood flow to compensate for a blocked vessel is known as what?
collateralization
37
Which mechanism of thrombosis is initiated by chemical factors released by damaged tissues?
Extrinsic mechanism
38
T/F: the extrinsic mechanism of thrombosis requires only components in blood and trauma to blood or exposure to collagen (or foreign surface).
False; this is true of intrinsic mechanism
39
What is clotting factor VI?
There isn't one anymore.
40
How many clotting factors are synthesized by the liver?
5
41
What depresses liver formation of II, VII, IX, and X by blocking action of vitamin K?
Coumarain
42
T/F: Hemophilia is sex linked on the Y chromosome.
False; it is sex linked on the X chromosome
43
85% of cases of Hemophilia are caused by a defect in which clotting factor?
factor VIII
44
What key step in clotting requires thrombin?
the conversion of fibrinogen to fibrin
45
What is the name of the autoimmune disorder where the body makes antibodies against phospholipids in cell membranes causing abnormal clots to form?
Antiphospholipid antibody syndrome
46
High blood homocysteine and diabetes mellitus are risk factors for what?
Heart Disease; probably a lot of other things too
47
What amino acid in the blood may irritate the blood vessels promoting atherosclerosis and can cause cholesterol to change into oxidized LDL?
Homocysteine
48
What amino acid, which makes blood more likely to clot, can be reduced by increasing intake of folic acid, B6 and B12?
Homocysteine
49
T/F: Specialized excitatory and conductive muscle fibers in the heart (i.e. SA node, AV node, Purkinje fibers) contract weakly.
True
50
What does syncytium or syncytial nature mean?
many acting as one (i.e. cardiac muscle)
51
What is the syncytial nature of cardiac muscle due to?
presence of intercalated disks
52
How long is the duration of action potentials in cardiac muscle?
.2-.3 seconds
53
T/F: There is a sharp increase of K+ in cardiac muscle at the onset of depolarization.
False; there is a sharp increase of Na+
54
T/F: Ca++ is increased during the plateau between depolarization and repolarization of cardiac muscle
True
55
T/F: K+ is decreased during the resting polarized state of cardiac muscle
False; K+ is increased during the resting polarized state of cardiac muscle
56
What is an action potential like in excitable tissue?
a pulse like change in membrane permeability
57
What happens to cardiac muscle permeability for Na+ during depol and repol?
increases at depol, decreases at repol
58
What happens to cardiac muscle permeability for Ca++ during depol and repol?
increases at depol, decreases at repol
59
What happens to cardiac muscle permeability for K+ during depol and repol?
decreases at depol, increases at repol
60
Which ion decreases at onset of depolarization: Na+, Ca++, or K+?
K+, the others increase; remember KDAD (K+ decreases at depol) and you can reason out the others
61
Which ion increases during repolarization: Na+, Ca++, or K+?
K+, the others decrease
62
T/F: Slow vs fast cardiac cells relates to channels that open during depolarization.
True
63
T/f: Typical cardiac muscles have both fast Na+ channels and slow Ca++/Na+ channels that open during depol.
True
64
T/F: in specialized excitatory cells like the SA node only slow Na+ channels are operational during depolarization increasing depol time.
False; should say only slow Ca++/Na+ channels
65
What kind of channels are selectively blocked by Tetradotoxin changing a fast response into a slow response?
fast Na+ channels
66
When wil an ion seek its Nernst equilibrium potential?
if ion channels are open
67
What is membrane permeability dependent on?
ion channels (being either open or closed)
68
What does Er (E subscript r) stand for?
Resting membrane potential
69
During the resting membrane potential in cardiac muscle, which channels are closed?
fast Na+ and slow Ca++/Na+ are closed
70
During the resting membrane potential in cardiac muscle, which channels are open?
only K+ channels
71
During the resting membrane potential, which ions are free to move until reaching their Nernst equilibrium?
K+; when they reach equilibrium, a stable resting membrane potential is maintained
72
What is the ration of Na+ pumped out to K+ pumped into the cardiac cell by the Na+/K+ pump?
3 Na+:2 K+
73
What does digitalis bind to and inhibit?
the Na+/K+ pump
74
If the Na+/K+ pump is inhibited, what will accumulate in the cardiac cell and increase contractile strength?
Ca++
75
When does the absolute refractory period occur?
during the plateau
76
When does the relative refractory period occur?
during repol
77
Which refractory period requires a supra-normal stimulus?
relative refractory period
78
T/F: In a slow response cardiac muscle cell, the relative refractory period is shortened.
False; it is prolonged about 25% longer
79
What does a prolonged refractory bundle in the AV node and bundle protect the ventricles from?
supra-ventricular arrhythmias
80
What is the normal pacemaker of the heart?
SA node
81
T/F: SA node has only slow Ca++/Na+ channels operational
True
82
What part of the heart spontaneously depolarizes at the fastest rate?
SA Node
83
T/F: the SA node has more negative resting membrane potential.
False; the SA node has a less negative Er
84
If you drive a self-excitatory cell at a rate faster than its own inherent rate, you will suppress the cell's own automaticity. What is this know as?
Overdrive Suppression
85
What cells are under the overdrive suppresion of the SA node?
cells of the AV node and the purkinje system
86
What delays the wave of depol from entering the ventricle?
AV node
87
What allows the atria to contract slightly ahead of the ventricles (0.1 sec delay)?
AV node
88
Which node has a slow conduction velocity due to smaller diameter fibers?
AV node
89
T/F: In absence of SA node, there will be no pacemaker for the heart.
False; the AV node may act as a pacemaker but at a slower rate
90
What happens to the cycle length as heart rate increases?
cycle length decreases
91
At a resting heart rate, is systole greater or lesser than diastole?
greater (if BP is 120/80, 120 is the systolic pressure)
92
Both the duration of systole and diastole shorten, but which one shortens more?
diastole
93
T/F: at high HR the ventricle may not fill adequately.
True
94
During systole, perfusion of the myocardium is restricted by what? especially where?
contracting cardiac muscle compressing blood vessels (especially in LV)
95
T/F: As HR increases, systole and diastole typically get closer in length.
True
96
During the cardiac cycle, when is the isovolumic contraction and ejection?
Systole
97
During the cardiac cycle, when is the isovolumic relaxation, rapid inflow, diastasis and atrial systole?
Diastole
98
During Isovolumic contraction (onset of Ventricular Contraction), what valve(s) close?
Tricuspid and Mitral valve
99
During Isovolumic contraction (onset of Ventricular Contraction), what valve(s) open?
Pulmonic and Aortic valve
100
When ventricular pressure rises above pulmonic and artery pressure, which valves open?
Pulmonic and Aortic valves
101
When ventricular pressure rises above atrial pressure, which valves close?
Tricuspid and Mitral valves
102
What valve closures terminate ejection of blood from ventricles?
semilunar valves (pulmonic and aortic)
103
What is it called when inflow to the ventricle is reduced?
diastasis
104
What marks the last phase of ventricular relaxation (diastole)?
Atrial systole
105
What is EDV?
End Diastolic Volume- volume in ventricles at the end of filling
106
What is ESV?
End Systolic Volume - volume in ventricles at the end of ejection
107
What is the term for volume ejected by ventricles? EDV-ESV
Stroke volume
108
What is a normal ejection fraction? (% of EDV ejected)
50-60%
109
What is the formula for finding ejection fraction?
SV/EDV x 100%
| systolic volume/end diastolic volume x 100%
110
What is the term for stretch on the wall prior to contraction which is proportional to EDV?
Preload
111
What is the term for the changing resistance (impedance) that the heart has to pump against as blood is ejected? This changes aortic BP during ejection from the left ventricle.
Afterload
112
What is the A wave associated with?
atrial contraction
113
What is the C wave associated with?
ventricular contraction
114
What is the V wave associated with?
atrial filling
115
T/F: Heart valves function by opening with a backward pressure gradient.
False; they open with a forward pressure gradient (when LV pressure> than aortic pressure, aortic valve is open)
116
When aortic pressure is greater than LV pressure, the aortic valve is closed. What kind of pressure gradient is this?
backward pressure gradient
117
Which valves have a stronger construction?
Semilunar valves (aortic and pulmonic)
118
What act as check lines to prevent prolapse of AV valves?
chorda tendineae
119
What increases tension of the chorda tendineae to help prevent prolapse?
papillary muscles
120
Which valves are thin and filmy?
AV valves
121
What kind of valvular dysfunction occurs when the valve does not open fully?
stenotic
122
What is meant when a valve is called insufficent or regurgitant?
valve is not closing fully i.e. leaky
123
What is produced when valves create vibrational noise?
murmurs
124
What valves may be stenotic if heart murmurs are produced during systole?
aortic and pulmonary valves
125
If aortic or pulmonary valves are insufficient, when will you hear a heart murmur?
diastole
126
When might you hear a heart murmur in patients with patent ductus arteriosis or combined valvular defect?
during both systole and diastole
127
According to the law of Laplace, as ventricular radius increases what happens to developed wall tension?
increases
128
What does chronotropic mean?
anything that affects heart rate
129
What does dromotropic mean?
anything that affects conduction velocity
130
What does inotropic mean?
anything that affects strength of contraction
131
T/F: Caffeine would be a negative chronotropic agent.
False; it would be a positve chronotropic agent as it increases the heart rate
132
According to the Frank-Starling Law of the Heart, the heart will pump all the blood that returns to it without allowing what in the veins?
excessive damming of blood
133
How does increased venous return affect cardiac muscle fibers?
increases stretch (this is an intrinsic effect)
134
How will an increased stretch on the SA node affect heart rate?
increases it
135
What is heterometic autoregulation?
within limits, as cardiac fibers are stretched the force of contraction is increased
136
What kind of influx into cells is associated with increased stretch?
Ca++
137
What will an increase of afterload lead to?
an increase is force of contraction
138
Direct stretch on the SA node will increase heart rate and what kind of permeability?
CA++ and/or Na+
139
ANS, Hormonal, Ionic and Temperature are all considered what kind of influences?
Extrinsic
140
What part of the ANS will be blocked by using atropine which blocks muscarinic receptors leading to increased HR?
parasympathetic
141
T/F: Symapthetic nervous system supplies ACh to cardiac cells.
False, SNS provides norepinephrine and Parasympathetics provide ACh
142
T/F: Most of the SNS influence on cardiac cells is due circulating catacholamines (epi and NE) released primarily from the adrenal medulla and find their way to the Beta-1 receptors.
False; indirect effects of catacholamines only account for about 15 % of SNS effects, and the other 85% is from direct innervation of cardiac cells
143
What reflex helps prevent damming of blood in the heart and central veins?
Cardioaccelerator refelx
144
Stretch on the right atrial wall increases stretch receptors which in turn send signals to MO increasing SNS outflow to the heart. What is this process called?
Cardioaccelerator reflex
145
Neurocardiogenic syncope involves which cranial nerve?
CN X
146
Occlusion of the circumflex artery (inferior wall infarct) plus an increase in left ventricle pressure and volume stimulates what reflex?
Benzold-Jarisch reflex (Neruocardiogenic syncope)
147
Stimulation of sensory ending mainly in the ventricles and some in the atria is associated with what reflex?
Neurocardiogenic syncope
148
Which artery supplies the inferoposterior wall of the left ventricle?
Circumflex artery
149
What results from neurocardiogenic syncope?
hypotension and bradycardia
150
What kind of hormones increase inotropic and chronotropic effects?
Thyroid hormones
151
What kind of hormones cause an increase in CO by increasing BMR?
Thyroid hormones
152
What is the major source of hormonal influence on the heart?
Thyroid hormones
153
What ion elevation results in dilation/flaccidity of cardiac muscle at concentrations 2-3 times normal levels?
K+
154
What ion elevation results in a decreased membrane potential?
K+
155
What ion elevation results in spastic contraction?
Ca++
156
T/F: for every degree F of body temp elevation, HR increases about 5 beats/min.
False; it actually increases about 10 beats/min
157
T/F: Decreased body temperature results in decreased HR and strength.
True
158
What is the most used (preferably) energy substrate for cardiac cells?
fatty acids
159
T/F: cardiac cells cannot use glycerol as an effective energy source.
False
160
How much of the energy utilized by the heart is converted to heat?
~75%
161
Most of the energy utilized by the heart that is not converted to hear, is used how?
pressurization of blood (>99% of the energy utiltized as work)
162
T/F: Pressurization of the blood is considered kinetic energy.
False; it is potential energy
163
T/F: the acceleration of blood to its ejection velocity is considered kinetic energy.
True
164
What heart malfunction can lead to aortic and pulmonic valves using as much as half of the energy utilized by the heart as work?
valvular stenosis
165
What device is used to measure potential difference across the surface of the myocardium with respect to time?
EKG
166
What is a lead?
a pair of electrodes
167
What is the term for the line that is connecting leads?
axis of lead
168
What is the transition line?
line perpendicular to axis of lead
169
What is the paper speed of an EKG?
25mm/sec
170
On EKG paper, how much time is equal to 1 mm?
0.04 sec
171
What is the normal range of HR?
60-80 bpm
172
What is tachycardia?
greater than 100 bpm
173
What is bradycardia?
less than 50 bpm
174
How long should the PR interval be on an EKG reading?
about 0.16 sec
175
What is occurring if the PR interval is greater than 0.20 seconds?
1st degree AV block
176
If the PR interval is less than 0.10 seconds, what can be suspected?
inadequate delay-possible accessory conduction pathway from atria to ventricle
177
What is happening at the P wave?
atrial depol
178
What is the MAJOR event during the QRS complex?
ventricular depol; atrial repol is buried in the QRS complex
179
What is occurring at the T wave?
ventricular repol
180
Type of Deflection - slide 83
memorize that chart
181
Frontal Plane Leads - slide 84
might want to know those
182
What positive chest lead (V lead) should be on the 4th intercostal space-right sternal border?
V1
183
What positive chest lead (V lead) should be on the 4th intercostal space - left sternal border?
V2
184
What positive chest lead should be on the 5th intercostal space - mid clavicular line?
V4
185
Where should the positive V3 lead be positioned?
equidistant between V2 and V4
186
What positive chest lead (V lead) should be located on the left mid axillary line?
V6
187
Where should the positive V5 lead be placed?
equidistant between V4 and V6
188
What is the negative electrode? (chest or V leads)
all limb electrodes hooked together
189
What are the 5 aspects of analysis of EKG?
Rate, rhythm/intervals, axis, hypertrophy, and infarction
190
300-150-100-75-60-50
Know that pattern for EKG analysis
191
T/F: Prolonged QT intervals have an increased incidence of sudden cardiac death.
True
192
What kind of arrhythmia is associated with a variance of more than 0.16 seconds between longest and shortest RR?
Sinus arrhythmia
193
During what type of Av Block is the depol wave from atria to ventricle delayed excessively (PR interval>0.2 sec)?
1st degree AV block
194
During which AV Block will some depol waves pass, but others be blocked? (dropped beat-P wave with no associated QRS complex)
2nd degree AV block
195
During which type of AV block are ALL depol waves from atria to ventricles blocked? (no relationship between P waves and QRS complexes)
3rd degree AV block
196
What is the normal range for the duration of QRS complex?
0.06-0.08 sec
197
What is considered a prolonged QRS complex?
greater than 0.12 sec
198
What type of QRS complex is associated with ventricular hypertrophy or conduction block in purkinje system?
Prolonged QRS complex
199
What does MEA stand for?
Mean Electrical Axis
200
What is the term for the average direction of ventricular depol?
mean electrical axis
201
What is the typical mean electrical axis?
ADIO- ventricle depols from base to apex and from endocardium to myocardium
202
How many frontal plane leads are used to analyze the vector of the MEA?
2 frontal plane leads
203
T/F: if the QRS of lead 1 and AvF is positive, MEA is irregular.
False; this is normal
204
What is the range for a normal MEA?
between -30 and +105 degrees
205
What occurs when a conduction block and hypertrophy shift the axis to the side?
axis deviation
206
What kind of axis deviation can be caused by the left bundle branch?
left axis deviation
207
T/F: hypertrophy can be associated with anything that creates an abnormally low work load on that chamber.
False; hypertrophy occurs from an abnormally high workload on that chamber
208
Systemic hypertension increasing workload on the left ventricle leads to what?
left ventricular hypertrophy
209
What condition may be associated with a prolonged QRS complex?
ventricular hypertrophy (left most likely)
210
T/F: an axis deviation to the opposite side of the problem is common with ventricular hypertrophy
false; the axis deviation is common to the same side as the problem
211
If the negative deflection in lead V1 added to the positive deflectin in V5 is greater than 35 mm, what condition is likely present?
left ventricular hypertrophy
212
what supplies blood to the myocardium?
the coronary arteries and their branches
213
T/F:cells near the endocardium may receive some O2 from chamber blood.
True
214
contraction of cardiac muscles limits myocardial blood flow. Especially in which chamber?
left ventricle
215
When does left coronary blood flow typically peak?
at onset of diastole
216
When does the myocardium take the maximum O2 out of the perfusing coronary flow?
resting HR
217
How does the heart meet increased demand of O2/blood flow to the myocardium/
increased coronary flow
218
At a resting HR, what is the extraction rate of O2 by the myocardium from the perfusing coronary flow?
about 70%
219
T/F: Normally the first cells to depol are the first to repol.
False; the first to depol are the last to repol
220
T/F: depol and repol waves are in opposite directions.
True
221
T/F: QRS and T wave point in opposite direction.
false; same direction
222
T/F: Ischemia prolongs depol and therefore speeds up repol.
false; ischemia prolongs depol and delays repol
223
Ischemia can cause depol and repol waves to be in the same direction. What will this do to the T wave?
causes an inversion of the T wave
224
If the T wave is inverted, which direction is its deflection relative to the QRS complex?
Inverted T wave will have opposite deflection of QRS
225
What can damage cardiac cells enough they lose their ability to repolarize?
infarction
226
When does most of the frank damage of an infarction occur?
upon reperfusion
227
T/F: reperfusion injury is associated with free radical damage.
True
228
T/F: During an infarction, the damaged area is in an abnormal state of repolarization.
False; damaged area is in an abnormal state of depol
229
What kind of current occurs between damaged and normal myocardium following an infarction?
"current of injury"
230
What could create a depressed baseline which appears as an elevated ST segment?
"current of injury" as a result of infarction
231
What are the preferred blood markers for myocardial injury?
Troponin T and I
232
What blood markers have the highest sensitivities and specificities for the diagnosis of AMI?
Troponin T and I
233
What contractile protein is not normally found in serum at a level high enough to be detected?
Troponin
234
When are troponins released at a level high enough to be detected?
when myocardial necrosis occurs
235
What molecules are highly sensitive and specific for cardiac damage?
Cardiac troponins T and I
236
T/F: Troponin T and I are of equal clinical value.
True
237
Roll tide?
Roll tide.
