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Circulatory Unit 8 ppt #2
Conduction System of the Heart
Name:__________________
The conduction system of the heart is the organized system of electrical impulses that stimulate contraction
and relaxation of the heart muscles, thus pushing blood through the chambers to the lungs and body.
This is the pathway of electrical stimulation:
https://www.youtube.com/watch?v=RYZ4daFwMa8
https://www.youtube.com/watch?v=v3b-YhZmQu8
Electrical Impulses generate_______________________.
Depolarization of muscle fibers=________________
Polarization or Repolarization= __________________
Systole=contraction
Diastole=relaxation
SA (Sinoatrial Node) is located on the upper part of
the____________ atrium. SA node is the Natural
pacemaker.
The SA node ____________________ and determines the pace of the heart rate.
Electrical impulses from the SA node spread throughout both __________________and stimulate them to
Contract. (pushing blood into the ventricles) Atrial ______________.
The AV (Atrioventricular) node is located on the other side of right atrium near the atrioventricular valve,
and serves as the gateway to the _______________. It delays the passage of electrical stimulation to the
ventricles to insure that the atria have ejected all the blood into the ventricles first.
AV node receives signals from the SA node and passes them onto the _________________________, known
as the ___________________________.
This bundle then is divided into right and left branches , which conduct the impulses towards the apex of the
heart. The signals are them passed onto ______________________turning upward, spreading throughout the
ventricular myocardium.
As the signals spread, muscle fibers depolarize and ________________________pushing blood to lungs and
aorta.
Electrical stimuluses’ of the heart can be recorded in the form of an ECG, electrocardiogram or EKG. This is a
recording of the action potentials produced by the nodes and cells of the myocardium. Each wave or segment
corresponds to a certain event of the cardiac electrical cycle.
P wave=
QRS Complex=
T wave=
More explanation:
P wave:
________________________________________electrical signals spread throughout the atria
and cause them to depolarize. This is represented by the P wave on the ECG.
Atrial contraction (systole ) starts about 100ms after the P wave begins.
PQ segment represents the time the signals travel from the_________________________________.
QRS complex marks the firing of the AV node and represents ventricular depolarization
Q corresponds to the ______________________________________________
R wave is produced by _____________________________of the main mass of the ventricles.
S wave represents the last phase of ________________________________________at the base of the heart.
During the QRS wave the Atrial repolarization (diastole)occurs but _________________________________
___________________________________
ST complex (right after total ventricle depolarization) represents the myocardial action potential. This is
when the ventricles contract and pump blood.(systole)
T wave represents ventricular repolarization (diastole) immediately before ventricular relaxation.
The cycle repeats itself with every heartbeat.
Cardiac Cycle:
The heart is 2 pumps that work together. Through repetitive contraction________________ and relaxation
_____________________of the heart chambers.
Blood moves through the circulatory system from areas of _________________to _____________pressure.
Contractions of the heart along with the valve system within the heart produce the ______________.
Describe heart sounds:
First heart sound= “Lubb”___________________________________________________________________
________________________________________________________________________________________
Second heart sound=”Dupp”________________________________________________________________
________________________________________________________________________________________
Third heart sound (sometimes)_______________________________________________________________
________________________________________________________________________________________
What is Mean Arterial Pressure? MAP
This is a measure of the ____________________________________________
MAP= CO X PR
PR= total resistance against which blood must be pumped
CO= Cardiac Output
CO= SV X HR
Cardiac reserve is the _____________________________________and Max CO.
What factors affect MAP? Please list:
How does the heart maintain its own homeostasis?
________________________________monitor blood pressure
_______________________________monitor pH, CO2, O2
Extracellular Ion concentrations______________________________________________________________
Body temperature _________________________________________________________________________
Draw your own flow chart to describe Baroreceptor Reflexes concerning changes in blood pressure...basics
Draw your own flow chart to describe Chemoreceptor reflexes concerning changes in blood pH…..basics
What happens to your heart as you age?