Cardiac Cycle and Conduction
what makes the "lup-Dup" sound in the heart?
- Atrioventricular valves (AV) closing makes the "LUP" sound - Semilunar valves (SV) valves closing makes the "DUP" sound
what happens in phase 5 of cardiac cycle?
- all blood is out of the ventricles, valves closes - atria = relaxed - ventricles = relaxed - atrioventricular valves = closed - semilunar valves = closed --> DUP sound
what happens in phase 3 of cardiac cycle?
- atria = relaxed - ventricles = contract - atrioventricular valves = closed --> LUP sound - semilunar valves = closed
what happens in phase 4 of cardiac cycle?
- blood starts to go to pulmonary semilunar valves - atria = relaxed - ventricles = contracts - atrioventricular valves = closed - semilunar valves = open
what happens in phase 2 of cardiac cycle?
- blood starts to squeeze out of atria to ventricles - atria = contracts - ventricles = relaxed - atrioventricular valves = oepn - semilunar valves = closed
what happens in phase 1 of cardiac cycle?
- most valves are open - blood flows from the atria to ventricles - atria = relaxed - ventricles = relaxed - atrioventricular valves = open - semilunar valves = closed
systolic
- ventricles contract - contraction - top #
QRS wave
- ventricles contract = ventricular depolarization - atria relax = atrial repolarization
diastolic
- ventricles relax - relaxation - bottom #
convert 75 BPM to 75 SECONDS PER BEATS
0.8 sec/beats
list the order of the intrinsic conduction system
1. sinoatrial node 2. atrioventricular node 3. atrioventricular bundle 4. bundle branches 5. purkinge fibers
The normal resting heart rate is about ________ times per minute.
75
Electrical link(s) between atria and ventricles
AV bundle
Delay(s) occurs here while atria contract
AV node
Which of these structures conduct(s) action potentials the slowest?
AV node
Increased pressure in the ventricles would close what valve(s)?
AV valves only
Contraction of the atria results from which wave of depolarization on the ECG tracing?
P wave
The first wave on an ECG that follows the firing of the SA node. This wave is small and signals the depolarization of the atria immediately before they contract.
P wave
Wave on the electrocardiogram (ECG) that follows the firing of the sinoatrial (SA) node
P wave
Wave visible on the electrocardiogram (ECG) representing atrial depolarization
P wave
The large wave that results from the depolarization of the ventricles and precedes the contraction of the ventricles.
QRS wave
Wave seen on an electrocardiogram (ECG) representing ventricular depolarization
QRS wave
Set(s) the pace for the entire heart
SA node
Which part of the intrinsic conduction system normally initiates the depolarizing impulse that causes a heartbeat?
SA node
The third wave that results from currents flowing during the repolarization of the ventricles.
T wave
Wave visible on the electrocardiogram (ECG) representing ventricular repolarization
T wave
What information can a clinician obtain from an electrocardiogram (ECG)?
abnormality in electrical activity of heart
Which part of the intrinsic conduction system delays the impulse briefly before it moves on to the ventricles?
antroventricular node
p wave
atria contracts = atrial depolarization
Where does the sinoatrial node send an impulse after it initiates the electrical signal?
atrioventricular (AV) node
What part of the heart's intrinsic conduction system carries impulses into the interventricular septum?
atrioventricular bundle
The first heart sound, "lub," is caused by the closure of the ________ valves.
atrioventricular valve (AV)
what occurs when the pressure in the ventricles rises higher than the pressure in the atria?
atrioventrivular valves close
Convey(s) the impulse down the interventricular septum
bundle branches
The beginning of the QRS complex of the electrocardiogram (ECG) immediately precedes (comes before) what event?
closing of the atrioventricular valves
what can be heard with a stethoscope most easily
closing of the atrioventricular valves
depolorization
contraction
What does the ECG wave tracing represent?
electrical activity in the heart
true/false: The QRS wave on an electrocardiogram is representative of ventricular repolarization.
false
true/false: The semilunar valves prevent the backflow of blood into the atria when the ventricles are contracting.
false
true/false:The heart sounds, "lub" and "dup," occur when the atria contract and subsequently when the ventricles contract.
false
Tacycardia
fast heart rate
What causes the aortic semilunar valve to close?
greater pressure in the aorta than in the left ventricle
Describe the pressures in the atria and ventricles that would cause the opening of the AV valves.
higher pressure in the atria than in the ventricles forces the AV valves to open and blood moves into the ventricles.
Convey(s) the impulse throughout the ventricular walls
pukinje fibers
repoloization
relaxation
The sinoatrial node is located in the ________.
right atrium
Which part of the conduction system initiates the depolarizing impulse, which spreads throughout the heart?
sinoatrial (SA) node
You notice a missing P wave on a patient's electrocardiogram (ECG) and believe there is a problem with the ________.
sinoatrial (SA) node
Which one of the following represents the correct path for the transmission of an impulse in the intrinsic conduction system of the heart?
sinoatrial (SA) node, atrioventricular (AV) node, atrioventricular (AV) bundle (bundle of His), right and left bundle branches, Purkinje fibers
bradycardia
slow heart rate
The anatomy of the intrinsic conduction system causes contraction of the ventricles to begin at the apex and move superiorly. Why is this important?
so blood is forced upward, toward the semilunar valves
Which term means heart contraction?
systole
what is the importance of valves?
the valves prevent the backflow of blood
the bicuspid valve is normally closed when
the ventricle is in systole
true/false: During ventricular systole, blood is ejected from the ventricles through the large arteries connected to the heart.
true
true/false: The part of the intrinsic conduction system of the heart that directly transmits impulses to the walls of the ventricles is the Purkinje fibers.
true
true/false: The sinoatrial (SA) node is the pacemaker of the intrinsic conduction system of the heart.
true
During atrial diastole, blood flows from the atria to the
ventricles
T wave
ventricles relax = ventricular repolarization
What does the QRS complex represent in the ECG wave tracing?
ventricular depolarization
ventricular systole or ventricular diastole: Pressure in the heart is low
ventricular diastole
ventricular systole or ventricular diastole: The atrioventricular (AV) valves are open
ventricular diastole
ventricular systole or ventricular diastole: Atrioventricular (AV) valves shut as pressure in the heart rises
ventricular systole
ventricular systole or ventricular diastole: Blood is ejected from the ventricles through the pulmonary trunk and aorta
ventricular systole
ventricular systole or ventricular diastole: Semilunar valves are forced open as pressure in the heart rises
ventricular systole
ventricular systole or ventricular diastole: Ventricular contraction
ventricular systole