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