3. Effect of Stannius ligatures on Frog’s Heart

• The rate of discharge of impulse is different for different pacemakers of the heart.
• The first Stannius ligature is applied between truncus arteriosus and the atria.
• The second Stannius ligature is applied between the atria and ventricle.

Q1. What is the effect of first and second stannous ligature on frog’s heart?

Q2. What is heart block? What are the different types of heart block?

• Interruption of impulse transmission from atria to ventricle is called heart block
• 3 degrees of heart block – First, second and third degree