The inter-atrial septum in the human heart can be best described as:

1. A thin muscular wall

2. A thick muscular wall

3. A thin fibrous tissue

4. A thick fibrous tissue

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.

In the foetus, the ductus arteriosus connects the

1. pulmonary vein with pulmonary artery

2. pulmonary artery with aorta

3. pulmonary vein with aorta

4. pulmonary artery with vena cava

In which one of the following pairs the two items mean one and the same thing?

1. Malleus - anvil

2. SA node - pacemaker

3. Leucocytes - lymphocytes

4. Haemophilia - blood cancer

The opening between the right atrium and the right ventricle is guarded by the valve named

(1) bicuspid valve                   

(2) tricuspid valve

(3) mitral valve                       

(4) semilunar valve