The heart has upper and lower chambers.
It is the upper right chamber of the heart.For diagram, see Related links below.
Atrial means pertaining to the upper chamber of the heart.
Frogs have 3 heart chambers
atrial
The left atrium
The left atrium
The upper chamber on the right side of the heart.
The lower chamber is the ventricle, and there are 2 upper chambers (they are known as atria).
The right atrium (upper chamber) and the right ventricle (lower chamber)
2, the atria is the upper chamber of the heart. since there is alower and upper chamber in the heart, and the upper part is the atria, do the math: four chamber divided in half (two lower and two upper and 2+2=4) equals two which gives the the number of atria!
Right Atrium