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92 Cards in this Set

  • Front
  • Back
SA node is located in
superior right atrium
What created heart beat
SA nodal pacemaker potential
AP's from SA node are propagated to right atrium AV node by
left atrium by
INTERNODAL TRACTS
BACHMANS BUNDLE
AV node is located
inferior right atrium
What is the function of AV node
Delays signal to allow atria to beat first and help fill ventricles
Also a back up pacemaker
Overdrive suppression
signal from SA node suppresses AV nodal pacemaker
Ventricular conduction system
starts with
bundle of His and branches into righ and left bundle branches which give rise to smaller branches
What controls heart rate
ANS
Sympathetic innervation... heart rate via...
increases
beta 1 receptors
Parasympathetic innervation decreases heart rate via
muscarinic receptors
Main 2nd messenger in heart
cAMP
cAMP dependent protein kinase phosphorylates "funny" Na channel increasing its rate of opening
beta 1 receptors stimulate cAMP via Gs
M2 receptors inhibit cAMP via Gi
Sinus rhythm
Normal
set by SA node, adult at rest is 70-80 bpm
Abnormal rhythms
AV nodal - starts if SA node fails since overdrive suppression stops - 40-50 beats per min
Ventricular - from ventricular conduction system if both nodes fail 20-40 bpm
Ectopic- in hypoxia, when heart cells become depolarized
Purkinje cells are specialized for
high velocity conduction, not contraction
Phase 0
Stimulus opens voltage gated Na channels (Na rushes in), membrane rapidly depolarizes
Phase 1
Na gates close quickly, K gates open
Plateau phase
200-250 msec, sustains contraction
Phase 2
slow Ca channels open, Ca binds to Ca channels on SR, releases Ca into cytosol which leads to contraction
Phase3
Repolarization - Ca channels close, K channels remain open
Phase 4
Resting membrane potential
Standard leads=
Einthovens leads
Augmented leads =
Goldbergers leads
What causes P wave
phase 0 in atrium
What causes Q, R, S wave
phase 0 in ventricle
What causes T wave
phase 3 in ventricle
What do intervals represent
Delay in propagation
P-R interval is
AV node delay
QRS (Q-S) interval
ventricular conduction delay
Q-T interval
Duration of ventricular action potential
Segments vs Intervals
Segments are straight or continuously curved lines between events
Intervals are periods of time that include events
Stroke VOlume SV is
amount of blood the heart forces in aorta with every heart beat
End diastolic volume
amount of blood in heart just before contraction
End systolic volume
amount of blood remaining in heart just after contraction
Formula for SV
SV = EDV - ESV
How can you increase SV
Increase EDV or decrease ESV
Cardiac output formula
CO= SV * HR= (EDV-ESV) * HR
What is the most important measure of cardiac performance
Cardiac output
Normal cardiac output
4-6 L/min
How do you increase CO
Increase HR
Increase EDV
Decrease ESV
Ejection fraction
Fraction of EDV that was ejected
Formula for EF
SV/EDV
Normal EF
0.5-0.75
What sets preload
Ventricular filling pressure
What regulates filling pressure
CENTRAL VENOUS PRESSURE
Best clinical measure of preload
EDV
Inotropic state is
hearts contractility - both rate of contraction and total force
Increasing inotropic state..
ESV
decreases
What determines inotropic state
Ca
Lusitropic state
Rapidity at which heart relaxes
Net effect of catecholamines
Increase both inotropic and lusitropic states of heart and shorten systole while increasing contractility
Afterload
pressure against which ventricle ejects stroke volume
Contraction velocity is ... to afterload
inversely related
Inotropic state is
hearts contractility - both rate of contraction and total force
P wave causes
atrial contraction
Increasing inotropic state..
ESV
decreases
QRS wave causes
ventricular contraction
What determines inotropic state
Ca
S1 first heart sound occurs when
ventricular pressure > atrial pressure so AV valves close
Lusitropic state
Rapidity at which heart relaxes
S2 second heart sound occurs when
arterial pressure closes arterial valves
Net effect of catecholamines
Increase both inotropic and lusitropic states of heart and shorten systole while increasing contractility
SP systolic pressure
maximum arterial pressure
Afterload
pressure against which ventricle ejects stroke volume
DP diastolic pressure
minimum arterial pressure
Contraction velocity is ... to afterload
inversely related
Pulse pressure
SP-DP
P wave causes
atrial contraction
A wave is caused by
atrial contraction
QRS wave causes
ventricular contraction
S1 first heart sound occurs when
ventricular pressure > atrial pressure so AV valves close
S2 second heart sound occurs when
arterial pressure closes arterial valves
SP systolic pressure
maximum arterial pressure
DP diastolic pressure
minimum arterial pressure
Pulse pressure
SP-DP
A wave is caused by
atrial contraction
Inotropic state is
hearts contractility - both rate of contraction and total force
Increasing inotropic state..
ESV
decreases
What determines inotropic state
Ca
Lusitropic state
Rapidity at which heart relaxes
Net effect of catecholamines
Increase both inotropic and lusitropic states of heart and shorten systole while increasing contractility
Afterload
pressure against which ventricle ejects stroke volume
Contraction velocity is ... to afterload
inversely related
P wave causes
atrial contraction
QRS wave causes
ventricular contraction
S1 first heart sound occurs when
ventricular pressure > atrial pressure so AV valves close
S2 second heart sound occurs when
arterial pressure closes arterial valves
SP systolic pressure
maximum arterial pressure
DP diastolic pressure
minimum arterial pressure
Pulse pressure
SP-DP
A wave is caused by
atrial contraction
c wave is when
ventricular contraction pushes AV valves closed
v wave is when
blood returning from veins builds up behind AV valves