In the heart
A. The left atrial wall is about three times thicker than the right atrial wall.
B. Systolic contraction normally begins in the left atrium.
C. Excitation spreads directly from atrial muscle cells to ventricular muscle cells.
D. Atrial and ventricular muscle contracts simultaneously in systole.
E. The contracting ventricles shorten from apex to base.

Karishma_Khanna Answered question July 13, 2022