Zoology - Body Fluids and Circulation Question with Solution | TestHub

Nodal tissue: It is a specialised cardiac musculature which is also distributed in the heart. It consists of nodal musculature (or nodal tissue) is autoexcitable.
A patch of this tissue is present in the right upper corner of the right atrium called the sino-atrial node (SAN). Another mass of this tissue is seen in the lower left corner of the right atrium close to the atrio-ventricular septum called the atrio-ventricular node (AVN).
The heart is mesodermal and myogenic. It is 4-chambered and protected by the pericardium.