In the nodal tissue of the human heart, the highest conduction velocity is seen in:
1. Internodal pathway
2. AV node
3. AV bundle or Bundle of His
4. Purkinje fibers
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