lab 9 Flashcards
(12 cards)
the depolarization and contraction of the atrial muscle during a typical cardiac cycle is known as:
atrial systole
true or false
in a cardiac cycle, electrical events precede mechanical events
true
what represents the depolarization of atrial muscle as a wave of negativity spreads from the SA node toward the ventricles?
P wave
what is ventricular diastole?
Ventricular relaxation, or diastole, follows repolarization of the ventricles and is represented by the T wave of the ECG.
the sequence of electrical events in each normal cardiac cycle is as follows:
SA node, AV node, Bundle of His, Bundle branches, Purkinje fibers
you are listening to your partners heartbeat through a stethoscope. you hear three sounds. What two normal sounds should you hear, and what do they represent? if the third sound happens between the two normal sounds, what could it represent? be as specific as you can
lub= closure of AV valve
dub= closure of pulmonary and aortic valves
an extra sound can be normal but it can alsoo represent heart murmur/ atrial fibrillation. then the SA node is overwhelmed by other electrical signals
what is the importance of AV delay? how would the efficiency of blood pumping affected if there was no delay at the AV node?
there is a critical pause to let atrial cardiomyocytes complete their contraction that pumps into ventricles before the impulse is transmitted to the cells of the ventricle itself. There would be a reduction in cardiac output, blood would regurgitate and flow incorrectly
The QRS complex measures ventricular depolarization. what other process is happening simultaneously, but is masked on the ECG?
the p wave when depolarization of atrial muscle as a wave of negativity spreads from the SA node toward the ventricles
what does an ECG measure?
the electrical cardiac impulse associated with the cardiac cycle may be detected at the surface of the body, amplified and recorded as an ECG or EKG
the particular pairing of electrodes, in which one or more electrodes are designated as negative and one is positive is called LEAD
in electrocardiography the term “lead” has two meaning:
- any one of the electrodes places on the body and the wire which connects the electrode to the ECG
- any of the twelve different pairing of electrodes (negative and positive) used to record ECG
bipolar lead
record (-) and (+) electrical activity with reference to 3rd electrode
unipolar lead
records the electrical activity between (-) and (+) electrodes without reference to the third electrode
