cardiac physiology Q4.

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the electrical trace in ECQ depends on?

1- direction 2- depolarisation/repolarization 3- size of the change in potential.

list the physiologic events of cardiac cycle.

1- SA node initiate impulse. 2- atrial muscle depolarisation. (P) 3- atrial contraction. 4- depolarisation of AV node and its bundle. 5- repolraization of atria. 6- depolrization of ventricular muscle. (QRS) 7- contraction of ventricular muscle. 8- repolrization of ventricular muscle. (T).

the ECG represents?

the electrical vector (magnitude and direction) of the cardiac cycle.

whats QRS complex?

depolriazation of ventricular muscle. Q- initial downward deflection. R- initial upward deflection. S- downward deflection (isoelectric point). Signup and view all the answers

how PR interval is measured and whats its function?

from the beginning of the P wave to the beginning of the R portion of QRS complex, used to determine if impulse conduction from atria to ventricle is normal, prolonged PR interval may suggest AV block ( as impuls passes through AV node into the ventricle during PR interv). Signup and view all the answers

whats PR segment?

is the flat line between the end of P wave and the QR complex in PR. it reflects slow impulse conduction through Av node, and used as a baseline/reference/isoelectric line. Signup and view all the answers

whats EDV?

end diastolic volume-the volume of blood in the ventricles at the and of diastole (130ml) Signup and view all the answers

whats ESV?

end systolic volume- the volume of blood in ventricles at the and of systole, (60ml). Signup and view all the answers

whats SV?

stroke volume-the amount of blood ejected from ventricles in one beat = EDV-ESV. Signup and view all the answers

whats cardiac output?

cardiac output= SV (ml/beat) * hear rate (beats/min). Signup and view all the answers

ECG

Represents the electrical vector (magnitude and direction) of the cardiac cycle.

QRS complex

Represents ventricular muscle depolarization.

PR interval

Time from the start of the P wave to the start of the QRS complex; it measures impulse conduction from atria to ventricles.

PR segment

A flat line between the end of the P wave and the beginning of the QRS complex, reflects the slow impulse conduction through the AV node.