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Apex > CV: anatomy and physiology > Flashcards

CV: anatomy and physiology Flashcards

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1
Q

Dromotropy

A

Describes the conduction velocity through the heart (velocity = distance/time)

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2
Q

Lusitropy

A

Describes the rate of myocardial relaxation during diastole

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3
Q

What is the primary determinant of resting membrane potential? What happens to RMP with changes to that value?

A

K.
Decreased serum K –> RMP becomes more -
Increased serum K –> RMP becomes more +

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4
Q

What is the resting membrane potential?

A

The electrical potential across a cell membrane at rest (inside vs outside the cell)

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5
Q

What is a threshold potential?

A

The voltage change that must occur to initiate depolarization

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6
Q

What ion determines threshold potential?
What happens to the TP with changes to that ion?

A

Ca++
Increased Ca ++: TP becomes more +
Decreased Ca++: TP becomes more -

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7
Q

A cell depolarizes when which ions enter the cell?

A

Na and Ca

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8
Q

A cell repolarizes when which ions enter/leave the cell?

A

Cl- enters
K + leaves

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9
Q
A
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10
Q

What is the refractory period of an action potential?

A

Occurs after a cell has depolarized. A period in which subsequent depolarization cannot occur

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11
Q

When does hyper-polarization occur?

A

After repolarization this occurs for a short period of time to help prevent depolarization too soon. This is a membrane potential more negative than baseline RMP

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12
Q

After an action potential, how is normal resting membrane potential reestablished?

A

Na K ATPase pump

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13
Q

How does Na K ATPAse pump work?

A

3 Na get pumped out
2 K get pumped in

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14
Q

What 2 purposes does Na K ATPase pump serve?

A
  1. Remove the NA + that enters the cell during depolarization
  2. Returns the K+ that left during repolarization
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15
Q

Does Na K ATPase pump need energy?

A

Yes, Na K ATPase pump uses ATP to fxn

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16
Q

What does Digoxin do to Na K ATPase pump?

A

inhibits it

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17
Q

How does severe hyperkalemia lead to cardiac arrest?

A

It inactivates Na ++ channels (they arest in their closed-inactive state). That is how extreme K+ produces cardioplegia during bypass

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18
Q

How many phases in myocyte action potential?

A

5

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19
Q

What is 1 key feature difference in how the myocyte action potential looks when compared to the neuron action potential? Why is it that way?

A

Prolonged depolarization which gives the heart enough time to contract during systole and eject all of the blood.

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20
Q

What happens during phase 0 of cardiac myocyte action potential?

A

Depolarization. Na enters the cell

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21
Q

What happens during phase 1 of cardiac myocyte AP?

A

Initial repolarization: Cl- enters cell and K+ leaves

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22
Q

What happens during phase 2 of cardiac myocyte AP?

A

Plateau phase. Ca ++ in and K + out

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23
Q

What happens during phase 3 of cardiac myocyte AP?

A

Repolarization. K leaves the cell

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24
Q

What happens during phase 4 of the cardiac myocyte action potential?

A

Maintenance of transmembrane potential with ATPase pump

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25
What is the resting membrane potential for a cardiac myocyte?
-90 mV
26
What is the threshold potential for a cardiac myocyte?
-70 mV
27
What is neuronal tissue resting membrane potential?
-70 mV
28
What is neuronal tissue threshold potential?
-55 mV
29
Describe the portions of the EKG that correlate with the cardiac action potential phases.
Reference drawing!
30
How many phases are in the SA node action potential?
3 4, 0, 3.
31
What happens during phase 4 of SA node AP?
Spontaneous Depolarization. Na+ (I-f) in and Ca ++ in (T type)
32
What happens during phase 0 of SA node AP?
Depolarization. Ca ++ in (L type)
33
What happens during phase 3 of SA node AP?
Repolarization. K+ out.
34
Which parts of the EKG correlate to the SA node action potential?
Reference image
35
What is SA node action potential resting membrane potential?
-60 mV
36
What is SA node action potential threshold potential?
-45 mV
37
What determines heart rate?
Intrinsice firing rate of the dominant pacemaker which is usually the SA node.
38
What is the intrinsic firing rate of SA node?
70-80 (faster in denervated heart)
39
What is the intrinsic rate of the AV node?
40-60 bpm
40
What is the intrinsic rate of he Purkinje fibers?
15-40
41
The rate of the sponatneous phase 4 depolarization of the SA node determines the intrinsic HR. (T or F)?
True
42
ALL of the cells in the ___ are capable of automaticity.
MYOCARDIUM
43
The first cells to start an action potential in the cardiac cycle are in the ____?
SA node
44
If the SA node is diseased or not being oxygenated (hypoxia) what cells will take over to set the heart rate?
AV node. Junctional rhythm is slower without a P wave because it originates here
45
What do volatiles do to SA node? What rhythm can they lead to?
Depress automaticity. Which is why they can lead to junctional rhythm.
46
Which tone is usually more prevalent? PNS or SNS in cardiac activity
PNS
47
Describe PNS innervation of the AV node
Left vagus
48
Describe PNS innervation of the SA node
RIght vagus
49
Describe SNS tone in SA and AV nodes?
Cardiac accelerator fibers (T1-T4)
50
We can alter the heart rate by manipulating which 3 variables?
1 Rate of spontaneous phase 4 depolarization (slope increases) 2 Threshold potential (becomes more -) 3 Resting membrane potential (becomes less -)
51
What is the oxygen delivery equation?
Reference apex
52
What is a normal PaO2?
100 mmHg
53
What is a normal SaO2?
98%
54
What is a normal CO?
5 L/min
55
What is a normal arterial content?
20 mL O2/dL
56
What is the CaO2 equation?
Reference apex
57
What is normal oxygen delivery value?
1,000 mL/min
58
Normal oxygen consumption (VO2)
250 mL/min
59
Venous oxygen content equation (CvO2)
Reference apex
60
What is a normal CvO2?
15 mL/dL
61
What is a normal oxygen extraction ratio? (Eo2)
25%
62
What is the oxygen consumption ratio equation? (VO2)
Reference apex
63
Ohms law is related to either current or flow. What are the equations for each?
Reference apex
64
Poiseuilles Law describes what?
Blood Flow
65
What is the equation for Poiseilles Law?
Reference apex
66
What is transitional flow when compared to laminar flow and turbulent flow?
Transitional flow is laminar flow along the vessel wall with turbulent flow in the center
67
Reynolds # can be used to determine whether the flow is __ or ___
laminar turbulent
68
What Reynolds # indicates flow will be laminar? What about turbulent? What about transitional?
**The higher the number the more likely its turbulent** Laminar: <2,000 Turbulent: > 4,000 Transitional: 2,000-4,000
69
Atrial kick contributes what % of the final LVEDV and by extension, CO?
20-30%
70
For what reason does CO decline with AFIB?
Loss of atrial kick
71
Explain excitation-contraction coupling
Reference apex
72
Law of Laplace wall stress equation:
Refer to apex
73
6 phases in the Wiggers diagram
-Atrial systole -Isovolumetric Ventricular Contraction -Ventricular Ejection -Isovolumetric Ventricular Relaxation -Rapid ventricular filling -Reduced ventricular filling
74
What parts of the Wiggers diagram occur during systole and which occur during diastole?
LV Diastole: -atrial systole -Iso ventr Relaxation -Vent Diastole LV Systole: -Isovol ventr contraction -Ventricular ejection
75
DIacrotic notch respresents what?
Aortic valve closure
76
Most of the stroke volume is ejected during the first _/_ of systole
1/3
77
__% of filling occurs during rapid ventricular filling
80
78
Go through and be able to say if MV/AV vlave are open or closed during each phase of the Wiggers diagram
Reference apex
79
6 components of the pressure volume loop? Where does each component lie? What does the y and x axis mean?
Reference apex
80
What is a normal EF?
> or equal than 50%
81
Mild dysfunction
41-49%
82
Moderate dysfunction
26-40%
83
Severe dysfunction
< or equal to 25%
84
What would Increased prelaod make the pressure volume loop look like?
Reference apex
85
What would decreased prelaod make the pressure volume loop look like?
Reference apex
86
What would Increased contractility make the pressure volume loop look like?
Reference apex
87
What would decreased contractility make the pressure volume loop look like?
Reference apex
88
What would Increased afterload make the pressure volume loop look like?
Reference apex
89
What would decreased afterload make the pressure volume loop look like?
Reference apex
90
The left and right coronaries arise from the
aortic root
91
Left main coronary splits into:
LAD circumflex
92
LAD perfuses the
Anterolateral wall of LV
93
Circumflex artery supplies the
left atrium as well as lateral and posterior walls of the LV
94
RCA perfuses the
Right atrium Right ventricle
95
Posterior descending artery perfuses the
inferior wall
96
The origin of which vessel defines coronary dominance?
Posterior descending artery
97
What is considered right coronary dominance?
RCA gives rise to the PDA 70-80% of pts
98
What is considered left coronary dominance?
Circumflex gives rise to the PDA
99
What is considered co-dominance
Circumflex AND RCA give rise to PDA
100
In most patients, what vessel supplies the SA node? What about in a small minority of patients?
RCA!! (70%) Circumflex
101
AV node receives blood from which vessel?
RCA
102
The bundle of His is perfused by the ___ in about 75% of patients
LCA
103
The left and right bundle branches are almost exclusively supplied by the _
LCA
104
What are the 3 main cardiac veins?
1. Great cardiac vein 2. Middle cardiac vein 3. Anterior cardiac vein
105
Each cardiac vein runs along a coronary artery. Which are next to which?
GCV and LAD MCV and PDA ACV and RCA
106
A small amount of deoxygenated blood gets dumped back into all 4 chambers via:
Thesbian veins
107
Main coronaries are considered epicardial vessels. They divide before penetrating deeper into the myocardium. (T or F)
T
108
What are the bipolar leads?
I II III
109
What are the limb leads?
aVR, aVL, aVF
110
What are the Precordial leads?
V1, V2, V3, V4, V5, V6
111
Which leads represent Inferior LV/RCA?
II III AVF
112
Which leads represent the lateral wall and circumflex?
I AVL V5 V6
113
Which leads respresent the septum and LAD?
V1 V2
114
Which leads represent the anterior LV and LAD?
V3 and V4
115
The best view for diagnostic LV ischemia is: The second best view is:
midpapilllary muscle level in short axis Apical segment in short-axis
116
At rest, the myocardium consumes oxygen at a rate of
8-10 mL/min/100 g
117
What is the myocardium extraction ratio of O2?
70%
118
What is coronary blood flow normally?
225 mL/min
119
What percent of CO goes to coronaries?
4-5%
120
The coronary vasculature like the brain vasculature autoregulates between a MAP of
60-140
121
What is the equation for coronary blood flow?
Refer to apex
122
What is the equation for coronary perfusion pressure?
CPP= Aortic DBP-LVEDP
123
What happens to flow through the LCA during ventricular systole?
Greatly diminished. Because endocardial vessels that branched off myocardial vessels are squished!
124
What happens to flow through the RCA during ventricular systole?
Remains constant because the RV does not generate pressure high enough to occlude endocardial vessels during systole
125
Whart is normal coronary sinus oxygen saturation?
30% because the myocardium consumes about 70% of oxygen delivered to it
126
When do most perioperative myocardial infarctions occur?
24-28 hours after surgery. Carries a 20% mortality
127
What does tachycardia do to supply and demand?
Decrease supply Increase demand
128
What does increased aortic diastolic pressure do to supply and demand?
Increase supply and increase demand
129
What does increased preload do to supply and demand?
Decrease supply Increase demand
130
As a general rule, increased Ca ++ causes ____ and reduced intracellular Ca ++ leads to (constriction or dilation)
Vasoconstriction Vasodilation
131
cAMP pathways results in increased cAMP which leads to vaso___
dilation
132
NO cGMP pathway results in increased cGMP which leads to vaso___
Dilation
133
Phospholipase C pathway increases IP3 and DAG which leads to vaso __
constriction
134
Which contain more mitochondria? Ventricular myocytes or Skeletal myocytes
Ventricular myocytes

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