Cardio 5 Flashcards
(35 cards)
T or F
All deoxygenated blood passes through either the SVC or the IVC on its way to the right atria. Why?
F
the coronary circulation has its own opening directly into the right atria
T or F
The Purkinje fibres can fire independently if the sinus node doesn’t generate an impulse. Why?
T
all cells in the conduction of the heart can fire their action potential to beat on their own, however, the sinus node is usually faster and “controls” the electric activity
T or F
The Purkinje fibres form synapses with the myocardium in ventricles, allowing ventricles to fire in synchrony
F
The whole statement is true EXCEPT CARDIAC CELLS DON’T HAVE SYNAPSES
T or F
Na+ ions passes through gap junctions of cells where one is active and the other is resting
T
It is a very small amount but Na+ does travel through the gap junction (most in the interstitial fluid)
What is a ECG/EKG
a recording of the electrical activity of the heart
What is the difference between ECG and EKG
ElectrocardioGRAPH: the device
electrocardioGRAM: the recording
What is the order of “waves” on the ECG reading
P QRS T
What happens during the P-wave? What is visible on the ECG reading, and why?
- Sinus node fibres: invisible
- Atrial activation: visible
- AV node activation: invisible
Anything that is a small activity will not appear on a reading
What happens during the Q-wave? What is visible on the ECG reading?
- His bundle activation: invisible
- Left bundle activation: invisible
- Septum activation: visible, Negative deflection
What happens during the R-wave? What is visible on the ECG reading?
- Purkinje fibres activation: invisible
- Ventricle activation
What happens during the S-wave? What is visible on the ECG reading?
- late activation of the ventricle: visible
Everything is activated at the end of this wave
How can the QRS complex be identified?
It’s the first negative deflection from the baseline
What happens during the T-wave? What is visible on the ECG reading?
- Ventricle repolarization: visible
What is a segment?
the baseline interval between two defelctions
What is an interval?
a range including deflections
Where is the P-R segment? What does it indicate?
From the end of the P to the start of the Q
It is the delay between atrial and ventricular activation
(there is no baseline between R and Q and a segment is the baseline interval so even if it is called the P-R segment it stops at Q)
Where is the P-R interval?
What does it indicate?
It starts at the beginning of P and ends at the beginning of Q
It is the Atrioventricular transit time
Where is the S-T segment? What does it indicate?
It starts at the end of the S wave and ends at the beginning of the T wave
It shows the time between depolarisation and repolarisation
Where is the Q-T interval? What does it indicate?
It starts at the beginning of the Q wave and ends at the end of the T wave.
It is proportional to the Action Potential time
Where is the QRS interval? What does it indicate?
From the start of Q to the end of S
it should be fast to show the activation of the heart ish
What does a long P-R interval indicate?
it may indicate a AV block
What does a long S-T segment indicate?
some tissues have abnormal AP (typical of an MI)
What does a long Q-T interval indicate?
there is a problem with repolarization
Why is an ECG useful in the medical context?
It allows people to identify cardiac problems in a non-intrusive way
