A person has atrial septal defect [hole in the interatrial septum]. This would result in the abnormal flow of blood from:
1. the right side of the heart to the left
2. the left side of the heart to the right
3. the pulmonary artery to the aorta
4. the ductus arteriosus to the aorta

Atria can completely empty during ventricular filling due to:
1. A-V node
2. A-V bundle
3. S-A node
4. Purkinje fibers

Under normal physiological conditions a higher cardiac output can be achieved by a higher:
1. extracellular ${\mathrm{K}}^{+}$ concentration
2. blood pressure in the systemic circulation
3. venous return
4. parasympathetic tone

Assertion: Prolonged aerobic exercise training may also increase stroke volume, which frequently results in a lower (resting) heart rate.
Reason: Reduced heart rate prolongs ventricular diastole (filling), increasing end-diastolic volume, and ultimately allowing more blood to be ejected.

1. Both assertion and reason are true and the reason is the correct explanation of the assertion.
2. Both assertion and reason are true but the reason is not the correct explanation of the assertion.
3. Assertion is true but reason is false.
4. Both assertion and reason are false.

Assertion: Although rare, but runners and athletes can suffer heart failure if they stop vigorous exercise abruptly.
Reason: To reduce the risk athletes are encouraged to follow hard exercise with moderate activity such as walking.

1. Both assertion and reason are true and the reason is the correct explanation of the assertion.
2. Both assertion and reason are true but the reason is not the correct explanation of the assertion.
3. Assertion is true but reason is false.
4. Both assertion and reason are false.