A person is feeling tired much of the time, and dizzy when he exercises. On his ECG, he has no P waves, but does have normal QRS complexes and T waves. Are the right and left atria contracting in this person? Are the ventricles contracting? What is happening to the amount of blood his heart can pump out with every beat?

for my physiology class .... thanks!

http://medinfo.ufl.edu/~ekg/2%20lists%20for%20Tachy.html#1st%20Key

normally the atria contract first which corrosponds to the P wave on the ECG & then the ventricles contract which corresponds to the QRS complex. the T wave signifies repolarization of the ventricles (sort of like the heart resetting itself & getting ready for the next beat).

if there r no P waves on the ECG it means that the atria r not contracting properly. they may not be contracting at all or they may be in a state of constant contraction & relaxation (called atrial fibrillation).

if the QRS complexes r normal then the ventricles r contracting properly. however, the atria, when contracting properly, push blood into the larger ventricles before they contract. therefore, if the atria r not contracting properly then the ventricles will not be filled with as much blood as usual & will not pump as much blood as usual. this could definitely make someone feel weak & dizzy.