Lab 10 Flashcards
Rhythm generators/ pacemaker cells
Cardiac cells that produce electrical signal
Conductors
Cardiac cells to spread the pacemaker signal
Contractile cells
Myocardium, cells that mechanically pump blood
Sinoatrial node
The pacemaker, generates the electrical signal which is spread to the ventricular muscle via the conducting pathways
Conducting tissues of the heart
Internodal pathways and atrial fibers, atrioventricular node, bundle of his, right and left bundle branches, purkinje fibers
Contraction
Occurs when depolarization reaches the contractile cells
Relaxation
Ocurrs when repolarization reaches the myocardial cells
Atrial contraction
When the SA node depolarizes the electrical stimulus spreads through the atrial muscles
After the SA node
The signal goes to the atrioventricular node via the internodal fibers where the signal is delayed 0.2 seconds when the atria contract which allows for ventricular filling
After the AV node
The signal travels through the rest of the conducting pathway resulting in ventricular systole
Sympathetic nervous system
Increases heart rate and strength of contraction when oxygen demands increase during exercise, inhalation, or drop in blood pressure
Parasympathetic nervous system
Slows the heart rate during exhalation
Electrocardiogram (ECG)
Recording of the electrical activity of the heart that is conducted to the body surface using electrodes
P wave
Results from atrial depolarization leading to atrial systole
QRS complex
Result of ventricular depolarization initiating ventricular systole
T wave
Result of ventricular repolarization leading to ventricular relaxation
Interval
Part of the ECG containing at least one wave and a straight line
Segment
Period of time from the end of one wave to the beginning of the next wave
Heart rate during inspiration
Increased
Heart rate during expiration
Early expiration increased, later expiration decreased
