Human Heart Cardiac Cycle

Doctors use a stethoscope to hear the sounds produced during each cardiac cycle. The second sound is heard when:

1.	AV valves open up
2.	Ventricular walls vibrate due to the gushing of blood from the atria
3.	Semi-lunar valves close down after the blood flows into vessels from the ventricles
4.	AV node receives a signal from SA node

What would be the heart rate of a person if the cardiac output is 5L, blood volume in the ventricles at the end of diastole is 100 mL and at the end of ventricular systole is 50 mL?
1. 125 beats per minute
2. 50 beats per minute
3. 75 beats per minute
4. 100 beats per minute

Which one of the following statements is correct?

1.	Increased ventricular pressure causes closing of the semilunar valves.
2.	The atrio-ventricular node (AVN) generates an action potential to stimulate atrial contraction.
3.	The tricuspid and the bicuspid valves open due to the pressure exerted by the simultaneous contraction of the atria.
4.	Blood moves freely from atrium to the ventricle during joint diastole.

Following are the stages of pathway for conduction of an action potential through the heart:

A.	AV bundle	B.	Purkinje fibres
C.	AV node	D.	Bundle branches
E.	SA node

Choose the correct sequence of pathway from the options given below:

1.	A-E-C-B-D	2.	B-D-E-C-A
3.	E-A-D-B-C	4.	E-C-A-D-B