The sino-atrial node is the normal pacemaker of the human heart because:

1.	It is located in the right atrium.
2.	It is the only part of the conducting system that can generate impulse.
3.	It can generate the maximum number of action potentials in the conducting system.
4.	It produces action potentials that are more in size than the other parts of the conducting system.

What percentage of ventricular filling is achieved by atrial contraction?

1. 30

2. 50

3. 70

4. 90

The second heart sound during the cardiac cycle is produced by the:

1. Simultaneous opening of the atrioventricular valves

2. Simultaneous closure of the atrioventricular valves

3. Simultaneous opening of the semilunar valves

4. Simultaneous closure of the semilunar valves

In a surface ECG the QRS complex represents:

1. Atrial depolarization

2. Atrial repolarization

3. Ventricular depolarization

4. Ventricular repolarization

Normal activities of the human heart are regulated:

1. Intrinsically

2. By the autonomic nervous system

3. By the brain stem

4. By the diencephalon

A common symptom produced by myocardial ischemia is:

1. Hypertension

2. Vertigo

3. Angina

4. Hyperventilation

An increase in the blood flow to the atria of the heart can cause the release of:

1. Erythropoeitin

2. Atrial natriuretic factor

3. Renin

4. Aldosterone

The steps of the cardiac cycle in sequence are...

1. isovolumic contraction, isovolumic relaxation, ejection, passive ventricular filling, active ventricular filling.

2. isovolumic relaxation, isovolumic contraction, ejection, passive ventricular filling, active ventricular filling.

3. isovolumic contraction, ejection, isovolumic relaxation, passive ventricular filling, active ventricular filling.

4. isovolumic contraction, ejection, isovolumic relaxation, active ventricular filling, passive ventricular filling

A decrease in plasma albumin levels is likely to affect:

1. Clot formation

2. Oxygenation of hemoglobin

3. Osmotic balance

4. Immune functions

Which of the following is a correct statement:

1. The volume of blood in pulmonary circulation is more than the volume of blood in systemic circulation at any instant

2. The blood pressure in pulmonary circulation is less than that of the systemic circulation

3. Double circulation is characteristic of all vertebrates

4. A double aortic arch is seen in birds and mammals