The pre-caval veins collect blood from

Left auricle receives pure blood from the:

What is the protective covering of the heart called?

............ can generate the maximum number of action potentials and is responsible for initiating and maintaining the rhythmic contractile activity of the heart. Therefore,it is called the pacemaker.

When the heart of a frog is removed,it will:

Contraction of the right ventricle of the human heart pumps blood into the......