Cardiac muscles are ......... in nature.

Which structure initiates the heartbeat?

When the heart of a frog is removed from the body,it continues to beat for some time. Select the correct statement$(s)$ from the following:
$(i)$ The frog is a cold-blooded animal.
$(ii)$ The frog does not have a heart-based circulatory system.
$(iii)$ The heart has myogenic properties.
$(iv)$ The heart is self-excitable.

What is the normal heart rate in a two-month-old infant?

In a patient,the cardiac pacemaker stops functioning. The doctor decides to implant an artificial pacemaker. Its function is similar to which of the following?

Describe the structure of myocardial tissue.