Atrial Contractions

Doctor asked:

1)walls of arteries composed of layers of muscle and elastic fibers that allow for contraction/expansion during heart cycle, aorta must be able to compensate for flow and is considered:
a) elastic artery b)fenestrated blood vessel c) muscular artery d) meta-arteriole
2)in a true capillary bed, this vessel connects artery to vein:
A)bundle of his b) thoroughfare channel c) vasomotor center d) mitral valve
3) what is normal cardiac output for person with heart rate of 75bpm
4)contracted cycle of heart begins with contraction of atrium due to stimulation from brain. this contraction is _____
5) asynchronous closing of atrioventricular valves would most likely be associated with
a) mitral valve prolapse b) atrial flutter c) heart murmur d) av valve stenosis

any help is appreciated

Question posted courtesy of: Harold

Josh A asked:

Can someone please explain to me what causes a-waves, v-waves, and x-descent on the atrial waveform and how are they individually related to the ekg?

Question posted courtesy of: Frances