Conduction System of Heart Flashcards
What electrolytes are active in the heart?
Sodium and Potassium
Where is the SA node located?
right atrium
SA Node Function
- brain talks to heart
- electrical conduction that helps with heartbeat comes down here
- pacemaker of heart that starts the beats
What happens if there are no SA nodes?
heart would beat slower
Where does the signal from the SA node go and what does it do?
the atria which is caused to contract and then AV Node
AV NODE (AtrioVentricular Node in between atria and ventricle)
sends the signal down the ventricular septum into the Bundle of HIS
Bundle of His sends signal to?
left bundle branch and right bundle branch
Purkinje Fibers
Small signal fibers that disperse the signal from the left & right bundle branches and activate the muscles in the ventricles at the same time
P Wave
Atrial depolarization
- atria are contracting
QRS Complex
Ventricular depolarization
- Ventricles contraction
What does a QRS complex look like?
Higher wave because there is more muscle which means more electricity
T Wave
- Ventricular Repolarization
- Ventricles resetting to be able to contract again
What is systolic pressure on an EKG?
PQRST
What is diastolic pressure on an EKG?
Disostic is everything outside of PQRST - it lasts longer & takes up more of the EKG
Cardiac Output
volume pumped by left ventricle in 1 minute
Formula for Cardiac Output
CO = HR * SV
CO - cardiac output
HR - heart rate (beats/minute)
SV - Stroke Volume
End-diastolic volume
the amount of blood that is in the ventricles before the heart contracts
- point where there is most volume
End systolic Volume
End-systolic volume is the volume of blood in a ventricle at the end of contraction
- point where there is least volume
Stroke Volume Formula
EDV - ESV
Preload
the amount of stretch in the heart’s ventricles just before they contract
What is preload determined by?
determined by the volume of blood returning to the heart (end-diastolic volume, EDV)
What causes an increase in stroke volume?
An increase in venous pressure leads to an increase in EDV, which in turn increases the stretch on the heart muscle.
- This increased stretch allows the heart to contract more forcefully, leading to an increase in stroke volume.
Afterload
the resistance the heart must overcome to eject blood into the systemic circulation
What is afterload determined by?
arterial (aortic) pressure
What causes a decrease in stroke volume?
An increase in afterload, such as high arterial pressure, leads to increased resistance for the heart to pump blood out, resulting in a decrease in stroke volume.
Contractility
refers to the strength of the heart’s contraction
