, Physiologist. 1  In four chambered avian and mammalian hearts, the two upper chambers are known as the atria. The atria are believed to act as primer pumps which boost the end diastolic volume (the volume at the end of ventricular filling) just before contraction of the ventricles.
Disunion follows the Civil War as it unfolded. New Orleans was the jewel of the Confederacy. In addition to being the Southâs largest city, it boasted considerable industry that produced ironclads, munitions and uniforms, among other items. More important, it controlled access to the Mississippi River from the Gulf of Mexico.
Without knowing it, Abbot and his men were witnessing the beginning of the Confederate Navyâs last, desperate effort to break the Unionâs ever-growing stranglehold on the Confederate capital. It would become one of the last important naval engagements of the Civil War â the battle at Trentâs Reach. The importance of the James River to the Richmond defense cannot be overstated. In April 1861, the mere rumor of the approach of the Federal warship Pawnee provoked near panic in the city.